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Rechargeable Batteries - Yes or No? 896

Posted by Cliff
from the they-keep-going-and-going-and-going dept.
TheFifthElephant asks: "I currently use quite a few devices that require various size batteries and I feel horrible just tossing them when they die. I saw a recharger at a retail store today and was thinking to myself how much waste it would reduce by using rechargeable ones. Which units have you used happily and/or which units have you heard of/read about satisfying someone else? Are the more expensive units better? What chemical rechargeable batteries last the longest/recharge the most?"
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Rechargeable Batteries - Yes or No?

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  • Nickel Metal Hyride (Score:5, Informative)

    by Alan Cox (27532) on Tuesday July 29, 2003 @05:47PM (#6564588) Homepage
    I'm using NMH batteries for just about everything battery powered in the house nowdays. NiCad's dont last as long and are very bad for the environment. The batteries I have claim to be good for several hundred cycles, which at the current rate is going to be about 30 years ;)
  • Batteries (Score:5, Informative)

    by theedge318 (622114) on Tuesday July 29, 2003 @05:48PM (#6564599)
    I have an old olympus camera that came with Ni-MH AA batteries and a battery charger ... it has lasted me near 4 years.

    Those batteries keep their energy for 3 months at a time easily, when I am not on vacations or otherwise using the camera.
  • If it helps... (Score:1, Informative)

    by Sir Haxalot (693401) on Tuesday July 29, 2003 @05:48PM (#6564606)
    I've had numerous recharger packs and they've all had the same recharge times (give or take a few minutes), but for rechargable batteries I'd go with Duracell, as they're more reliable. Hope this helps :)
  • by douglips (513461) on Tuesday July 29, 2003 @05:48PM (#6564611) Homepage Journal
    These batteries kick serious booty. In my digital camera, a single charge outlasts even the best disposable batteries by a factor of 2 or 3. In about a year I've already saved more in disposable battery cost than I spent on the charger and cells.

    Definitely worth the investment. I have Panasonic brand, but only because that's what they had at Costco. I doubt that there is a big difference between brands of similarly-rated cells.
  • Ray O Vac (Score:5, Informative)

    by buckeyeguy (525140) on Tuesday July 29, 2003 @05:49PM (#6564616) Homepage Journal
    Have had good results with 1800mAh NiMH RayOVac AA-size batteries in cameras with flash. Havne't used them for much else yet. Had less satisfactory results from Radio Shack-brand NiMH ones. YMWV.
  • All kinds. (Score:4, Informative)

    by RatBastard (949) on Tuesday July 29, 2003 @05:49PM (#6564635) Homepage
    I've used all kinds of rechargables, from cheap Radio Shacks and Mallorys, to expensive Sony units. They are all pretty cose to the same, save for newer lithium-ion batteries.

    I keep enough batteries in the chargers to replace the batteries in every device at the same time. And it does save an amazing amount of money in the long run. Most of my rechargables last for five to seven years before they stop being able to hold a charge.

    The only batteries I have not replaced with rechargables is AAA-size. At that size the rechargables don't hold enough charge to be worth it.
  • Re:NiMH (Score:5, Informative)

    by Anonymous Coward on Tuesday July 29, 2003 @05:50PM (#6564646)
    NiMH batteries are great but they have the downside of losing charge very quickly "on the shelf" so you can't keep a bunch of charged MiMH batteries ready to use.
  • Re:NiMH (Score:3, Informative)

    by edgarde (22267) <slashdot@surlygeek.com> on Tuesday July 29, 2003 @05:50PM (#6564650) Homepage Journal
    For consumer batteries in conventional form factors (AA, AAA, C, D & whatever a 9-volt is called), you basicly have Nickel-Metal Hydride (NiMH), and Nickel-Cadmium (NiCd). Neither last as long as disposables, but NiMH last substantially longer, and are more environmentally friendly (i.e. they don't contain lead or mercury). Downside: NiMH costs more.

    RadioShack [radioshack.com] sells both kinds.

    Lithium ion batteries ... uhm, exist but I know nothing about them. They have advantages over NiMH but don't come in the common form factors I mentioned above, and are more expensive.

  • Recycle (Score:5, Informative)

    by marshac (580242) on Tuesday July 29, 2003 @05:50PM (#6564652) Homepage
    You know, you can recycle your dead batteries, right? When I worked at Radio Shack a long time ago, we took in dead batteries and sent them off to be recycled. I'm not sure if this was just my store, or a company wide thing, but there are free recycling services out there.... so don't throw them away!
  • by Anonymous Coward on Tuesday July 29, 2003 @05:51PM (#6564659)
    Yes.

    You misunderstand the purpose of the over/under moderations.

    They exist merely for the purpose of anonymous modslapping from the editors.

    You'll notice a comment that makes a good, well thought out point - but is contrary to slashbot groupthink - will dissappear to -1 Overrated, with no other moderations done. It's not a troll, flamebait, offtopic, or redundant - but it is something slashdot doesnt want heard, so out damn spot.

    You'll notice idiotic rambling zealot comments, like "I think gentoo is awesome and RIAA is stupid!" get whacked up with Underrated mods. Same thing. Such comments add nothing, and would be left at 0 if they were not put on a pedestal by the editors.

    Whenever you see overrated or underrated moderations, that's an editor shaping the conversation towards his viewpoints.
  • iGo Juice (Score:4, Informative)

    by BWJones (18351) on Tuesday July 29, 2003 @05:51PM (#6564669) Homepage Journal
    I have been using the iGo Juice [ententeweb.com] to power my Powerbook and peripherals and find it to be quite the appealing solution including charging handhelds and cell phones when I travel. The iPod gets charged through the Firewire port (awesome idea), so other than that, I'm set. All of these devices appear to use Lithium Ion batteries and have decent performance, (especially the Powerbooks).

  • Walmart anyone? (Score:4, Informative)

    by RealBeanDip (26604) on Tuesday July 29, 2003 @05:53PM (#6564695)
    For AA batteries, go to Walmart and pick up the NiMH rechargables at 1800mAh and a charger. I think you can get a combo pack (4 batts and charger) for something like $12, which is a heckuva a good deal. These batteries last and last and last.

    The 1800mAh batteries are an absolute requirement for digital cameras. Using standard alkalines, I would get just over 30 digital pics in my Toshiba camera. Using 4 1800 NiMH, I get about 200 before needing a charge.

    I also use them in my FRS radios and GPS, and they last forever.

    I've also used various brands of NiMH's besides the Walmart specials and haven't seen much difference in quality.
  • In a word: yes (Score:3, Informative)

    by jandrese (485) * <kensama@vt.edu> on Tuesday July 29, 2003 @05:53PM (#6564708) Homepage Journal
    I picked up some NiMH (Rayovac's in case you care) batteries a couple of years ago and I've never gone back. I use them in my digital camera (where I get about 300 full res (1760x1168) pictures out of the 4AAs. I use them in my Palm VIIx (a battery hog in the best of days) where they easily last as long as the Alkalines (there's even a feature in PalmOS to switch the battery meter over to NiMH). Even when you consider the inital cost ($12 for 4 AAs), they quickly pay for themselves (I've taken ~3000 pictures on the 8 AAs I bought for the camera and recharged the palm batteries more times than I can count) with only half a dozen recharges.

    One thing to be careful of is that the batteries do lose a bit of life over time, although my original sets seem to be holding up quite well. Also, rechargeable in general seem to leak charge faster than Alkalines, so they're not really a wonderful idea for long life low draw devices like remote controls.

    Don't bother with NiCad. They have sucked from Day 1. I've never tried the rechargeable Alkalines. When you buy a charger, make sure you get one that supports NiMH, not all of them do.
  • Environment (Score:3, Informative)

    by spoonist (32012) on Tuesday July 29, 2003 @05:54PM (#6564716) Journal

    Please do not just throw away dead batteries. Please recycle them [rbrc.org].

    I use tons of NiMH batteries in my various gadgets.

    The prices aren't the best, but REI [rei.com] has all you probably need right here [rei.com].

    Battery Barn [batterybarn.com] has some good prices.

  • by swb (14022) on Tuesday July 29, 2003 @05:56PM (#6564734)
    NiMH rechargables. You should have no problem finding 1800mAh AA cells, and these hold up quite well to frequent charge/discharge cycles. I've been using them for about 4 years and they can take quite a pounding.

    What's even better is that a lot of cordless stuff with NiCads can be converted to NiMH by making your own battery packs. Internally many of the packs are just a few AA cells soldered together.

    If you do this, look for places that sell flat-top and soldertab batteries. Some of the cartridge-type battery packs won't fit the normal button-top batteries, and soldering can be hard on the cells if you try to solder directly to the cell itself.

    I did this with my Uniden 900 Mhz DSS phone. Before it would go ~90 minutes on a fresh (new and fully charged) NiCad pack. Now I can get over 2 hours of talk time, leave the phone out of the charger over night, and still have it be perfectly usable the next day.

    I was concerned about the charging system, but not any more. A friend has done this for a long time (NiCad->NiMH conversions) and hasn't had any problems, and neither have I.
  • by Anonymous Coward on Tuesday July 29, 2003 @05:56PM (#6564745)
    Started using GE lead-acid AAs in my WalkMan (the really old one that was silver/gray that took 4 AAs) on ski trips.. they'd last the entire night.

    These days I'm using a few diffrent ones in my Oly C-2100 digital SLR... The Oly ones that came w/ the camera are starting to show their age, but still hold an ok charge in a pinch. I've been most happy with the latest Energizer brand AAs NiMH (still in the Oly charger). The Energizer NiMH AAs are no more expensive than the Energizer High output Lithiums at most stores, and for the old Walkman (still in service, but for biking now) and my camera, the rechargables are great.

    just my $0.02 US
  • by temojen (678985) on Tuesday July 29, 2003 @05:57PM (#6564752) Journal

    Heat.

    It increases the rate of the reaction, allowing the battery to supply more current. It also works if you roll them back and forth in your hands for a while. I had to learn this trick while living just south of the Yukon border. Cold weather stops the reaction, and your batteries can't provide enough current.

    This trick works for both rechargeable and disposable batteries, as long as they're not completely dead.

  • Re:NiMH (Score:2, Informative)

    by murphyslawyer (534449) on Tuesday July 29, 2003 @05:57PM (#6564754) Homepage
    Lithium Ion batteries are great for a couple of reasons - first, they have relatively high energy densities compared to NiMh or NiCd batteries. For example, right now on my desk I have an AA factor LiIon battery that puts out 3.6V for 2500 mAH. Compare this to a NiCd that will have 1.2V for about 1200 mAH. The downside is that the LiIon battery costs about $8.

    The second reason LiIon batteries are superior is because of their discharge characteristic. They tend to hold their voltage until almost completely discharged, then the voltage drops like a rock. This is great for portable electronics that require a relatively stable voltage supply to operate. NiCd and NiMh batteries have discharge curves closer to that of a standard Alkaline AA, in that the voltage tends to fall as the battery discharges. This means that the actual amount of time the battery is good is less, since some of the stored energy can't be used because the voltage on the battery isn't high enough for the electronics to use.

  • Re:lower impedance (Score:3, Informative)

    by alienw (585907) <alienw@slashdot.gmail@com> on Tuesday July 29, 2003 @05:57PM (#6564768)
    The lower impedance cannot possibly cause a risk to equipment unless said equipment is extremely badly designed. The reason for the labels is usually the lower voltage. Sometimes, the equipment will shut down long before the battery is exhausted, simply due to the lower voltage.
  • by egg troll (515396) on Tuesday July 29, 2003 @05:58PM (#6564776) Homepage Journal
    Imaging-resource.com did a great review [imaging-resource.com] of a ton of rechargeable batteries. The electronics geek in you will enjoy his breakdown of how he conducted the tests.
  • Battery FAQ (Score:5, Informative)

    by meehawl (73285) <meehawl,spam&gmail,com> on Tuesday July 29, 2003 @05:59PM (#6564795) Homepage Journal
    This is a very comprehensive Battery Guide [buchmann.ca]. [buchmann.ca]
    The mention of NiMH on a battery pack does not automatically guarantee high energy density. A prismatic NiMH battery for a mobile phone, for example, is made for slim geometry and may only have an energy density of 60Wh/kg. The cycle count for this battery would be limited to around 300. In comparison, a cylindrical NiMH offers energy densities of 80Wh/kg and higher. Still, the cycle count of this battery will be moderate to low. High durability NiMH batteries, which are intended for industrial use and the electric vehicle enduring 1000 discharges to 80 percent depth-of discharge, are packaged in large cylindrical cells. The energy density on these cells is a modest 70Wh/kg.
  • by Krellan (107440) <krellan@nOSPAm.krellan.com> on Tuesday July 29, 2003 @06:01PM (#6564818) Homepage Journal
    I use Rayovac Renewal rechargeable alkaline batteries for pretty much every device I own that uses batteries. It's very efficient and has paid for itself many times through the years I've been using them.

    I chose Rayovac Renewal because it was the first rechargeable alkaline battery made. My grandfather actually picked it up before me, and he's usually the last to touch a new invention! He does like to be efficient and save money, though.

    The batteries do wear out over time, though. I have a few bad batteries mixed in with my good batteries, and so sometimes I put in newly recharged batteries and they don't last as long as they should. If I had it to do over again, I would number each battery in sequence when they were purchased, so I would know which batteries are getting old and could throw them out. Now, I have no real way of knowing which are old and which are new, because they all look the same.

    Rayovac Renewal puts out the full 1.5 volts per battery (AA, AAA, etc.).

    Avoid Energizer Accu! I learned this the hard way. They only put out a lousy 1.2 volts per battery! That's just 80% of the voltage you're supposed to be getting. This is borderline fraud!

    Devices that have strict voltage requirements, like digital cameras, just will not run at all with Energizer Accu. It might be tolerable for flashlights and old radios, which can be a little dimmer/quieter while still working fine, but for any modern electronic device it will cause problems.

    Devices with Energizer Accu will run for a very short time, if at all, as their voltage starts at 80% of normal and not at 100%. So, if the device requires something like 75% of rated voltage in order to function correctly, you will only have 5% of headroom with Accu versus 25% for a normal battery. So, assuming that batteries drop voltage at the same rate, your device will fail five times faster with Accu!

    Accu does have one advantage, though. They do make a "9-volt" (really 7.2V) rechargeable battery. Rayovac Renewal does not make this battery, to my knowledge, so I am forced to use Accu for various devices that require a 9V battery.

    If they made a true 9V Rayovac Renewal battery, it would make me happy!
  • A few tips (Score:5, Informative)

    by PurpleFloyd (149812) <zeno20NO@SPAMattbi.com> on Tuesday July 29, 2003 @06:02PM (#6564821) Homepage
    I've used rechargables for quite some time now, and they do seem worth the extra cost. A few things I've learned:
    • Buy a good charger. Cheap ones can fry batteries, take longer to charge, and can go up in smoke easily. Also, make sure it can charge NiMH batteries as well as NiCDs; if you have high-drain devices like digital cameras, then you want NiMHs, and probably don't want to pay for a new charger for 'em. Expect to pay $30-$50 USD for a decent one.
    • When you buy batteries, look at the milliamp-hour rating. That's the capacity they can hold: for example, an 1800 mAh AA could supply (theoretically) 1 mA for 1800 hours, 1800 mA for one hour, or anything in between. While mAh ratings do tend to be stretched a bit (the tests are performed under the most favorable circumstances possible), it's the best guide you can get to how long the battery will last in the device you plan to use.
    • Don't buy more battery than you need. Your TV remote probably doesn't need expensive 2200 mAh NiMHs, so put in cheaper 800 mAh NiCDs.
    • You'll be better off buying online than anywhere else. I've had good luck from several companies, but note that the "Energizer" branded batteries are relabeled and marked-up generics; you can get better batteries, cheaper if you go with other companies.
    • Get extra batteries. You should have a few sitting around for when something important goes dead; don't just buy what all your devices need. Get a few extra of each type you use, or just keep alkalines around to use while recharging.
    • Don't be too hard on your batteries. Many good chargers have a "fast" and a "trickle" setting; don't use the "fast" setting unless you absolutely can't wait overnight. Fast charges are hard on batteries; once or twice won't hurt much, but repeated fast charges can cause a significant drop in total battery life.
    • Finally, if you have some high-drain devices and want to get more battery life, try hacking something onto the AC adaptor. A good guide to doing this with your digital camera is here [dansdata.com]; the principles are pretty much the same for anything else that has an AC adaptor socket.
    Good luck!
  • by kzinti (9651) on Tuesday July 29, 2003 @06:04PM (#6564857) Homepage Journal
    I'm using NMH batteries for just about everything battery powered in the house nowdays. NiCad's dont last as long and are very bad for the environment.

    Agreed.

    According to a very long article/discussion I read somewhere (sorry, can't remember the URL), NiCd batteries are easily damaged by overcharging, which tends to reduce their capacity over the life of the battery - and there is no so-called "memory effect".

    I use NiMH batteries in my digital cameras and love them. I have a set of 1450 and 1600 mah AA's; 1600 was the best capacity available when I bought them, but today you can find 1800 and 2000 mah capacities.

    One problem with NiMH cells is that they don't hold a charge very well on the shelf - in other words, if you charge up a set, set them aside, then pick them up weeks or months later, you're likely to find that they've lost much of their charge (can't recall how fast that "shelf-drain" occurs). So I keep one set in the camera and one set in the charger. I've had both sets of batteries about 3 years and charged them hundreds of cycles, and I think I've noticed a bit of a decrease in effective capacity over that time, but not very much. NiCd cells would have died an aggravating death by now.

    The lithium-ion batteries in my iPod and Dell laptop seem to have both good capacity and shelf life, but the laptop batteries died after a couple of years and I had to replace them... VERY expensive. I hope the iPod battery fares better.
  • Re:NiMH (Score:3, Informative)

    by z84976 (64186) on Tuesday July 29, 2003 @06:04PM (#6564859) Homepage
    One drawback to the voltage curves of the lithium cell would be that devices which use a meter-type battery level indicator (which of course would have been tuned to track the power left in an alkaline) will report that you have an almost full charge up until that crash. Minor annoyance, but an annoyance nonetheless.

    I don't own any lithium cells, other than the ones in cellphones, but based on my cellphone experience I'd say they probably charge quickly too. If you go with NiMH you can get 1 hour fast chargers for them, which is certainly good enough for my needs right now. Those chargers won't charge NiCads tho, so be careful.

    Also, can't help but note... if you've got a AA battery that's putting out 3.6 volts, I'd say you've got quite a defective battery. An AA battery is supposed to put out 1.5 volts, plus or minus a small fudge factor. You'll likely blow LED's in an LED flashlight if you double the voltage like that... imagine what it can do to other stuff.
  • Battery Tests (Score:4, Informative)

    by Daikiki (227620) * <daikiki@wanaCOFFEEdoo.nl minus caffeine> on Tuesday July 29, 2003 @06:04PM (#6564860) Homepage Journal
    NiMH batteries last a factor 2-3 longer than NiCd batteries, are less environmentally unfriendly, and lack the memory effect that made people hate rechargeable batteries in the first place. What this means is that a fully charged MiMH battery will last as long, if not longer, than a regular alkaline battery in the same application. Capacity of batteries is rated in milliamp hours. A penlight rated at 2000 mAh will, in theory, provide 2 amps of power for an hour. It goes without saying that bigger is better.

    This guy [imaging-resource.com] has tested several dozen different types of NiMH penlights for use in digital cameras. Although there are many other uses for the things, this seems to be one of the more common and at least vaguely representative of what to expect.

    When choosing a charger, make sure it supports, and is set to charge NiMH batteries. Running a NiCd cycle on them will yield unsatisfactory results. There are fast chargers available that will charge your batteries in as little as an hour and it's commonly accepted that these don't harm the batteries much.
  • by llamafirst (666868) on Tuesday July 29, 2003 @06:05PM (#6564867)
    This guy has done VERY thorough testing on lots of brands of AAs, and geeks might also find much of the data useful to read regarding Watt-hours vs mAh and Simple Run Times, even if you don't care about AAs:

    http://www.imaging-resource.com/ACCS/BATTS/BATTS.H TM [imaging-resource.com]

    An important snippet from that page:

    The Importance of the Charger (!) One of the most interesting things I found was that the right (or wrong) charger can make a difference of nearly 2x in the results! The worst chargers (in terms of completeness-of-charge) produced "charged" batteries with only half the stored energy of ones charged with the best chargers. Interestingly though, the best overall results were obtained by combining the worst fast-charger with an inexpensive trickle-charger for topping-of and charge maintenance. - This combination was also the gentlest on the batteries. (Stay tuned for a detailed overview of battery chargers as I can get to it. For now, you can just take as given that the Maha C204 charger was among the most consistent I tested, and charged the batteries to close to their maximum capacity every time. ...

    I use a digital camera (Minolta Dimage 7Hi) and I use his recommended ones: Powerex 1800 batteries and the very effective Maha C204 [imaging-resource.com].

  • eBay (Score:2, Informative)

    by Zagar (610861) on Tuesday July 29, 2003 @06:05PM (#6564871)
    2000mAh Ni-Mh AA cells are very cheap on eBay. You will also find good chargers for under 20$. I recommend that you stay away from thoses fast-charge models since your cells won't last as much. Ni-Mh cells have much more energy than alkalines. As an example, I was looking for some cells to put in my digital camera. The only thing I found was a pair of alkaline cells. After about 5 shots, they were dead.
  • by PocketAces (627624) on Tuesday July 29, 2003 @06:06PM (#6564879)
    For some interesting information about rechargeable batteries and their chargers, take a look at some FAQs about batteries and chargers [greenbatteries.com]. The most important thing is the charger. It can greatly affect how long your batteries will last, in terms of time per charge, and how many charges it can take.

    Personally, I have used the Maha brand battery and charger and have been happy with them.

  • by Latent Heat (558884) on Tuesday July 29, 2003 @06:06PM (#6564882)
    The NiMH has its uses, but so does the Alkaline Rechargeable (Rayovac Renewal). Rayovac makes a charger that works with both.

    The alkaline starts out at around 1.63 volts and discharges to around .9 volts before it is considered dead. The NiMH is flat at 1.2 volts. For some apps, the NiMH battery comes up "low battery" (like in my friend's pager) because the pager may consider an alkaline discharged to 1.2 volts as about done with. So you have to find out if 1.2 volts per cell will run your appliance.

    The other thing about the NiMH is that it self discharges -- it is even worse than the NiCad, only it isn't supposed to have the memory effect that a NiCad has (the camcorder which doesn't fully discharge the NiCad which means the NiCad never ever seems to ever recharge and ever run the camcorder).

    Now for the alkaline rechargeable. They say you can put ordinary alkalines in one of those chargers -- tried it and it won't burn the house down, but it won't hold a charge, or it will recharge but have really high internal resistance on discharge. I guess you have to pay for those fancy Renewal batteries if you want to recharge an alkaline.

    OK, here's the deal. A fully charged alkaline is over 1.6 volts (none of this 1.2 volt business), and it is supposed to hold its charge forever (I measure .01 volt per day degradation). The rub is that you can't discharge them (ha, ha). What I mean is that if you use them in a flashlight and discharge them until the light gets dim, you have discharged them down to that .9 volt, and you are lucky to get one or maybe two recharges (if that) out of them. The trick is to discharge them only down to 1.5 volts and then freshen 'em up in the charger. Apparently they only like to be discharged a little bit and then recharged as soon as possible -- I use D-cells in a couple of flashlights (a 4-cell Mag and a 2-cell ordinary flashlight). If I use a flashlight on a project (like to change a dead car battery at night, or to poke around a crawlspace, I recharge them as soon as I can). I am told they will live (Rayovac data sheets) nearly forever that way.

  • by meehawl (73285) <meehawl,spam&gmail,com> on Tuesday July 29, 2003 @06:06PM (#6564889) Homepage Journal
    There's also this Battery Shootout [imaging-resource.com] ranking system, skewed towards small portable electronic device effectiveness.
  • Re:All kinds. (Score:3, Informative)

    by Elvisisdead (450946) on Tuesday July 29, 2003 @06:07PM (#6564896) Homepage Journal
    I've used AAA in everything from my infra-red keyboard to the ultra-mini MagLite. From my experience, the NiMH ones I have (Radio Shack) last about as long as alkaline.
  • by NetMasta10bt (468001) on Tuesday July 29, 2003 @06:07PM (#6564899)
    I too use NiMH batteries, and I highly recommend them. But when I first started using them I skimped on a cheap 'dumb' charger which can overcharge/overheat batteries and it takes 8 hours for a charge.

    I recommend a smart charger like the Maha C204F from Thomas Distributing [thomas-distributing.com]. They have all sorts of batteries at great prices (not affiliated just a happy customer).

    This charger also has a conditioner feature that will help bring those older batteries back to life (the ones that you were using the dumb charger on before!).

    Batteries that I've charged with this charger last 3x as long in high drain applications like in my GPS unit.

  • by JoeCommodore (567479) <larry@portcommodore.com> on Tuesday July 29, 2003 @06:08PM (#6564903) Homepage
    I use NIMH in my digital Camera (an older Olympus D-460) and they are great. I keep two sets in my camera bag, the NIMH and a standard high-quality alkaline set, Normally I use the NIMHs till they are low (which can be several days of moderate camera usage) and then swap in the standard batteries and continue till I can get the NIMHs recharged. Recharging takes a few hours but once charged they are ready for hours more work. With this the 'normal' batteries last for a few months of occasional use.

    If you are using them on something you depend on (camera, camcorder, etc.) It would be prudent to have a set of high-quality standard cells for backup like I do.

    NICADs historically develop a memory problem and may not hold much of a charge later on (not that they hold much in the first place from my experience). NICAD technology may be different now, so choose your rechargable batteries sensibly.
  • Re:NiMH (Score:5, Informative)

    by lars_stefan_axelsson (236283) on Tuesday July 29, 2003 @06:10PM (#6564922) Homepage
    I use NiMH batteries for my wireless mouse, and my camera. Got a simple charger over at radioshack, and it works quite well.

    About chargers, understand that there are two types out there; timer controlled and -deltaV controled.

    You want the -deltaV controlled, which monitor the voltage on the battery to sense when they're fully charged. The timer controlled chargers, will overcharge the battery, and nothing kills batteries like overcharging.

    Now it turns out that for low amp applications, even a simple charger will get enough performance out of the batteries, but for more serious applications such as digital camera, a real charger could tripple the number of cycles you'll get out of the batteries.

    Also, watch out for 'micro processor controlled.' While all -deltaV chargers will have that on them somewhere, it may also mean timer controlled (as in there's a micro processor keeping time somewhere).

    There was a good test this spring in the Swedish equivalent of Consumer report, but unfortunately it's in Swedish (and you have to be a subscriber). The noteworthy point was that not all -deltaV chargers are created equal, one undercharged, so you may want to check around. Expect to pay serious money for a serious charger. The good ones in the test were $100-$200 in Sweden, you'd pay perhaps 50%-75% of that in the US (I don't really know the battery charger market).

    P.S. Use NiMH. Better for you, and no memoy effect. With a -deltaV charger you can easily top them up if you've had them on the shelf for a while (they'll lose their charge in a couple of months when stored).

  • by ReaperOfSouls (523060) on Tuesday July 29, 2003 @06:13PM (#6564965) Homepage
    It works because the batteries operate via a chemical reaction, basically the acid inside eats away at the container. When the acid inside is mostly equilized it does not have enough umgh to work any more. By adding heat, i.e. direct sunlight, it adds enough umgh to make it happen. You should be able to notice something similar when you shake just dead batteries as well..
  • by linuxwrangler (582055) on Tuesday July 29, 2003 @06:15PM (#6564990)
    NiCd and NiMH have somewhat lower voltage (~1.2v) than alkaline (~1.5v) but they also have a far lower internal resistance so if you short a NiCd/NiMH you can get far more current than if you short an alkaline.

    NiMH also self-discharge quite rapidly - several percent/day. In some apps the self-discharge drains the battery faster than the device does. This also makes them lousy for emergency uses unless they are always on charge.

    The upshot of this is that if you have a very low draw app like noise-cancelling headphones or a radio-only walkthing then you may want to stick with alkaline as they last weeks to months anyway and the loss of 0.6v (for 2 cells) may cause problems.

    You may also want to stick with alkaline for certain very high-draw apps. Some halogen high-intensity flashlight bulbs specifically recommend against using rechargables. They are designed for use with alkaline and without the limiting factor of the internal resistance of the alkaline battery the bulb will pull too much current and burn out quickly.

    On the other hand moderately high draw things like digital cameras are perfect for NiMH. The high draw depletes the alkaline to a point that it can't supply enough current in short order - a couple dozen pictures in my camera. NiMH will power it for a couple hundred. Unless your use level borders on "never", rechargables are the way to go for cameras, flash units, handi-talkies and similar devices.

    Beware of chargers that recharge pairs of batteries, however. I recently had some old NiMH batteries that I thought were dead (~12 pix per charge). I had been using the Kodak charger that I got with my camera - it charges cells in pairs. Unfortunately if cells are out of balance it doesn't work well.

    I bought a PowerX charger and after a couple charge cycles the batteries were working great again - and they are almost 5 years old.

    The PowerX has gotten favorable reviews from ham operators and camera buffs. It has two charge cycles so if you don't need a charge RightNow! you can switch to a slower setting to prolong the life of your battery. Also, each battery is on an independent channel so each battery gets an appropriate charge and you won't be driven crazy when you have an oh-so-common 3 battery device. After charging it switches to a trickle mode to keep the battery topped-off. I've only had mine for a couple of weeks but so far it beats the heck out of my old chargers. Comes with a car cable, too.
  • From 650ma for the original shitty nicads to something like 1850ma for the latest generation of Nickle-metal-hydride.

    The 1850ma batteries last long on a charge than the best alkaline batteries do new, and you can recharge them a thousand times or so, with no memory effect. The original 1650ma batteries I got with my Fuji camera still gave a full charge two years later when the camera was stolen.

    I never buy disposable AAs for anything anymore, instead I have a bunch of AA NmH.
  • Re:NiMH (Score:1, Informative)

    by Anonymous Coward on Tuesday July 29, 2003 @06:17PM (#6565014)
    I use NiMH and Rayovac's "rechargable alkaline" batteries. The Rayovac batteries seem to be cheaper and hold their charge better. They only work (safely) in a Rayovac charger though. :(
  • look for the rating. (Score:3, Informative)

    by twitter (104583) on Tuesday July 29, 2003 @06:17PM (#6565016) Homepage Journal
    Compare prices by the rating. If the rating in milli-Amp-hours (mAh) is not on the battery or packaging, you don't want it. If you know your device's current draw, you can make a reasonable guese at how long your batteries will last. Conversly, you can get your device's average current draw from how long your batteries last. Wal Mart has reasonbly priced high capacity NMH. Between that and a fancy Radio Shack charger, I have few battery problems.

  • Re:NiMH (Score:4, Informative)

    by Jason1729 (561790) on Tuesday July 29, 2003 @06:17PM (#6565017)
    It's too bad the moderators marked this BS informative.

    NiCd and NiMH batteries hold their terminal voltage until almost completely discharged too, they are both actually slightly better than Li-ion in that respect. They will also work will at current draws of up to 1C for NiCd and 2C for NiMH with no loss of performance.

    The Lithium batteries that can do 2.5Ah @ 3.6 volts in an AA form factor aren't even rechargable.

    Jason
    ProfQuotes [profquotes.com]
  • That's great, but never ever consider doing this with lithium-ion cells. Their recharge cycle must be precisely controlled, or they turn into pretty decent torches. Lithium-ion devices are heavily tested and regulated.

    NiMH cells are great, they always last me around 3x longer than the best alkalines I can buy. So if I charged them once, used them, and threw them away, I'd be breaking even. Every additional charge is just icing on the cake.
  • NiMH/Li-Ion (Score:2, Informative)

    by derrith (600195) on Tuesday July 29, 2003 @06:19PM (#6565042)
    I've tended to use Nickel-Metal Hydride batteries in my cdplayers and my archos jukebox and they seem to be middle of the road. No memory (or unnoticeable) in high draw devices and they tend to be cheap. I'd assume that Li-Ion are the best to use as that is what my iPod and creative nomad are using at the moment. I've also seen that Li-Ion is what many cameras use in addition to a myriad other devices I haven't listed. NiMH is your best bet for not too long of a useage and a middling to low price range. LI-Ion for longer useage and higher prices.

    .
  • by caouchouc (652238) on Tuesday July 29, 2003 @06:21PM (#6565064)
    about 2200(I think) mAh for a AA, compared with the low 1000's range for most Ni-MHs

    I've got a bunch of 2100 mAh NiMH AA's, so they're catching up. :)
    They do have the distinct disadvantage of discharging themselves, but it's not a problem at all when you use them as much as I do. They're also good for a lot more recharge cycles than alkaline.
  • Re:NiMH (Score:4, Informative)

    by john_lewmanny (576761) on Tuesday July 29, 2003 @06:23PM (#6565083)
    You can if you keep them in the charger.

    Not every charger, actually. Check yours to learn wether it has this 'keep alive' feature.
  • Re:NiMH (Score:5, Informative)

    by kzinti (9651) on Tuesday July 29, 2003 @06:23PM (#6565084) Homepage Journal
    NiCd and NiMh batteries have discharge curves closer to that of a standard Alkaline AA...

    But Alkaline batteries have high internal resistance, so they're not terribly useful in high-current devices like my Kodak digicam. That high resistance causes the batteries to heat quickly, and because resistance increases with heat, it gets worse the longer you use the device. The voltage drop across the resistance causes the output voltage to drop, and before long it can drop below a useful voltage. In high-current devices, NiMH and NiCd batteries work much longer than alkaline batteries, in part because they don't heat as much.

    This isn't just theory; I've tried alkalines in my digicam, and they don't last for more than a handful of photos, not nearly as long as my usual NiMH cells. So I can use alkalines, but only in a pinch. For low-current devices like a CD player, alkalines may last as long as NiMH or NiCd, but when they're done you have to throw them away.
  • by TFloore (27278) on Tuesday July 29, 2003 @06:24PM (#6565092)
    Rechargable batteries are wonderful things. Like a lot of other /. readers, I have a pocketful of AA NiMH batteries. There are some things you should be aware of with rechargables before you jump into them, though.

    (Mostly AA specific)

    First, make sure your battery-powered device is rated to handle rechargable batteries. Alkaline AA batteries are nominally 1.5volts. "Fresh" batteries will probably test to 1.56volts in a digital multimeter. NiMH AA batteries are nominally 1.2volts, and will usually test as 1.26volts freshly-charged. If your device has a voltage meter (if it shows "battery power remaining" it does) then you need to be sure it can handle running with the different voltage. My old family-band radios (some motorola model, don't remember which) were made assuming alkalines at 1.5volts, and gave noticably less powered-on time with NiMH batteries than with Alkalines. The batteries still had juice in them, but were putting out a slightly lower voltage than the radio wanted, and the radio turned itself off.

    Second, all rechargable batteries (except possibly lead-acid/gel-cells) have a normal charge cycle rating. This means, effectively, that they can be recahrged that many times, and then they stop holding a charge, the chemistry inside breaks down after that many charge cycles. By chemistry:
    NiCad = 500 charge cycles.
    NiMH = 400 charge cycles
    Lithium Ion = 350 charge cycles

    After you recharge them that many times, expect them to become noticably less useful. This is part of why laptop batteries are only warranted for a year, incidentally... 350 charge cycles, 350 days of charge/discharge (about a year), and you have a battery that doesn't last nearly as long as when it was new. This is also why people that buy laptops like intelligent chargers, and don't recharge immediately upon reconnecting to a wall regardless of charge remaining. Recharge based on charge % remaining, and the battery lasts a lot longer, so wait until the battery gets below, say, 85% charge, and it will last 2-4 years instead of one. Intelligent chargers in laptops will check the charge remaining automatically, and only charge when it drops below a given threshold.

    Third, you have different self-discharge rates with different batteries, aka, the shelf life. Alkalines are really good here, they have a quite long shelf life, usually measured in years.
    NiCads are less good than alkalines, and especially with the multi-cell NiCad packs where you are concerned with polarity reversal, you want to recharge your NiCads every few months, to keep the charge level above a certain minimum where one cell in a pack might get too low, reverse polarity, and basically kill your multi-cell battery pack.
    NiMH batteries self-discharge at about 1-2% per day. Yes, a "freshly-charged" battery that is left on a shelf for a month will be down by 25-50% charge. This is environment dependent, of course, varying with temp and humidity mostly.
    Lithium Ion batteries have about the best shelf-life of rechargables, about the same as NiCads, really. Still nowhere near alkalines, though. (Again, leave your laptop sitting on a shelf for 3 months, you'll probably have a dead battery. Be aware, and plan accordingly.)

    With all this said, I still love rechargable batteries, and use them whereever they fit the device specs.

    Oh, and fair warning, if you travel outside the US. Most of the cheap NiMH chargers you see in Walmart and everywhere else are US voltage only, they work with 110V 60Hz AC ONLY. If you are travelling anywhere outside the US and Canada, get an international charger, that can handle 50/60Hz and 110/120/220V. You'll be much happier, and not unpleasantly surprised when your charger gets very very warm and then suddenly stops charging. Bear in mind that the carribbean, while very near the US and supposedly US power specs, has crappy power regulation on wall plugs, and you'll want an international charger there too. Just another thing to be careful of.
  • by m.dillon (147925) on Tuesday July 29, 2003 @06:25PM (#6565104) Homepage
    I would recommend you throw your rechargeable Alkalines away. 'Rechargeable' Alkalines are really just normal alkalines with a beefy casing to reduce leakage, but the full charge drops off significantly even after the first recharge cycle and gets worse from there. Alkalines are fragile beasts compared to NiMh. With an Alkaline the charger has to be very careful not to damage the battery. With NiMh the charger pretty much just pushes in current and limits by temperature, and the battery is very forgiving to chargers that overdo it.

    -Matt

  • by caouchouc (652238) on Tuesday July 29, 2003 @06:26PM (#6565118)
    NiMH is probably a bad idea for a PDA with months of run time.

    They'd last a few hundred re-uses, but you'd have to swap them every three weeks as they passively discharge themselves faster than the PDA will. They're designed for more high-drain devices, like video cameras, game & audio devices, etc...
  • NiMH batteries (Score:5, Informative)

    by pbegley (84849) on Tuesday July 29, 2003 @06:27PM (#6565136) Homepage
    I replaced over 100 batteries used in our household (three daughters, geek father) with NiMH. No problems at all. I get the next to highest mAh rated batteries from Thomas Distributing (just a happy customer) and I use an Altek 5798 charger. The tri-state LED's give a good status on when its done charging.

    I had a few go bad over the past few years, but I know several sets have had hundreds of charges.

    The last AA set I got were 2000 mAh and they are great in my Fuji digicam.

    www.thomasdistributing.com - don't let the 'web designer on acid' interface bother you, they have always had the best price and reasonable delivery. I even like the 'free gifts' (synth chamois car cloth, plastic battery holders).

    Hope this helps!
  • by kzinti (9651) on Tuesday July 29, 2003 @06:34PM (#6565195) Homepage Journal
    There is no such thing as a NiCd memory effect [repairfaq.org].
  • I buy mine from... (Score:2, Informative)

    by Leomania (137289) on Tuesday July 29, 2003 @06:36PM (#6565211) Homepage
    Thomas Distributing [thomas-distributing.com]

    I have the Maha C204F charger and I love it. It has been *very* gentle to my batteries. I have had the best luck with the 1800mAh Powerex batteries, but I see they have the 2200mAh available now as well.

    I can't recommend NiMH batteries highly enough for high-drain devices like digital cameras; they last longer than alkaline in such applications. But for low-drain devices like remotes, I disagree with some of the posters' suggestions to use them. They self-discharge at a much greater rate than alkaline and are unsuitable for such applications (unless you like finding dead batteries in your remote every few weeks... been there, done that).

    Please note that it's getting much easier to recycle the non-rechargable batteries now; I save mine up and take them to the local transfer station where they gladly accept them for recycling. Probably not as common in areas with lower population densities, tho.

    Cheers,

    - Leo
  • by evilpenguin (18720) on Tuesday July 29, 2003 @06:40PM (#6565246)
    The memory effect is a myth (as your link indicates). I have talked to several chemists and electrical engineer involved in battery design and manufacture and not a single one I've talked to thinks there's anything to it.

    The advice you are given by people who claim the "memory effect" exists is to periodically run your batteries flat. I am told by these chemists and engineers that the more often you "deep cycle" your rechargable batteries (of any type, lead-acid, Ni-Cd, NiMH, Li-ion, whatever), the shorter the total AH life of the battery, guaranteed.

    Put those puppies on the charger as often as convenient, and NEVER run them out flat if you can avoid it.
  • by ouzel (655571) on Tuesday July 29, 2003 @06:43PM (#6565284)
    In my opinion, NiMH batteries are the way to go. I'm not kidding when I say I'll take them to my grave :-) I bought twelve AA batteries years ago for my digital camera, and I'm still using them daily. They've gone through hundreds of charging cycles and still last much longer than alkaline batteries in the same application.

    A couple of notes:
    • Buy a "smart" charger. This is important - you want a charger that will provide just a trickle of juice when the batteries become fully charged. This way, you don't have to worry about removing the batteries from the charger after X number of hours. Maha makes fantastic smart chargers. The C401FS [nimhbattery.com] is really nice - I have its older brother, the C204F.
    • Go for the highest mAH rating possible, unless you're using the batteries in something like a mini flashlight or remote control. I bought the green Sanyo [ripvan100.com] 1600 mAH "industrial grade" AA batteries three years ago and they have been exceptional performers. Sanyo now has 2100 mAH batteries, and here Here [nimhbattery.com] are some more good ones (2200 mAH).
    • NiMH batteries can cause problems with things like flashlights -- they work best in electronic devices such as digicams. I have a couple of Mini Maglites (that take 2 AA batts), and have found that the bulbs burn out much more quickly when using NiMH batteries. The documentation that comes with the new bulbs mentions that, too.
  • Energizer (Score:3, Informative)

    by _iris (92554) on Tuesday July 29, 2003 @06:44PM (#6565303) Homepage
    I've had a wonderful experience with the Energizer Rechargables [energizer.com], using the wall charger by the same name. I was given the charger and a set of batteries. I'm still on the same set of batteries (which I mostly use for my Olympus D-390 digital camera). I've recharged them about 8 times and they haven't lost any lifespan between charges (my old Rayovac Renewable system suffered from this).
  • by Ruie (30480) on Tuesday July 29, 2003 @06:47PM (#6565336) Homepage
    Radio shack has a nice page about different batteries [radioshack.com].
  • Re:NiMH (Score:3, Informative)

    by KiahZero (610862) on Tuesday July 29, 2003 @06:53PM (#6565384)
    Don't buy from RadioShack, buy from GreenBatteries [greenbatteries.com]. I've shopped with them before, and gotten great deals... haven't seen $2.75 each for NiMH AAs in 12 packs at WalMart. Unfortunately, they don't seem to have the common form factor Li-Ion batteries either, but I've been sastisfied with the NiMH so far.
  • Re:NiMH (Score:4, Informative)

    by Jason1729 (561790) on Tuesday July 29, 2003 @06:55PM (#6565416)
    You seem to be circling the point, but just don't get it. Here's a few hints:

    1. The voltage drop of the LED is unrelated to the voltage of the battery; the battery voltage just needs to be greater than the drop across the LED for the LED to light.
    2. For a given brightness of LED, the current needs to be the same; it wouldn't be enormous for a higher voltage. In theory, the LED is a short circuit anyway, to the current is whatever the battery can put out regardless of voltage (at least for the split second until the LED fries.
    3. There is a current limiting resistor in series with the LED, which according to Kirchov's voltage law has the rest of the voltage dropped across it. So in that case, you know the resistance and voltage dropped across the resistor, therefore you know the current through it, and by Kirchov's current law, you know the current through the LED.
    Now, it should be fairly obvious that the larger the voltage dropped across the resistor, the more stable the current will be against slight changes in battery voltage. Therefore, you want a relatively large voltage potential dropped across the resistor (at least as much as across the LED) to keep the current stable. That means the voltage of the battery should be at least double the voltage drop of the LED.

    Jason
    ProfQuotes [profquotes.com]
  • Re:NiMH (Score:2, Informative)

    by sacherjj (7595) on Tuesday July 29, 2003 @06:57PM (#6565427) Homepage
    This is an important thing to keep in mind when choosing battery types. I will generally put up with the reduced run time in a CD player for my NIMH AAs, just to keep from having to buy alkalines in bulk. Alkalines have higher internal resistance than NiMH, which is higher than NiCad. NiMH is best for most moderate draw devices, because the increased energy density overshadows the extra losses do to internal resistance compated to NiCads. When you get up into the exterme draws, like high performance electric motors for R/C airplance and cars, or even full size electric vehicles, the lower resistance of the NiCad makes up for the reduced energy density in run time.
  • by Anonymous Coward on Tuesday July 29, 2003 @07:02PM (#6565490)
    2) "Disposable diapers"
    Need I say more?

    Yes you do. What is a bigger problem for the millions of people living in LosAngeles: Disposable diapers or the lack of drinking water due to a million cotton diapers a week needing washing?
  • Re:A few tips (Score:3, Informative)

    by PurpleFloyd (149812) <zeno20NO@SPAMattbi.com> on Tuesday July 29, 2003 @07:03PM (#6565498) Homepage
    Most of the "smart" chargers I recommend will cut the current entirely once they detect the voltage drop that the cells exhibit at end-of-charge. As for using a NiCD charger on NiMHs, just don't. While trickle chargers tend to be fairly safe, NiCDs can safely take more charge current than NiMHs can; extra charge current for either chemistry is dissipated as heat and isn't good for the battery. You end up with the same problems as if you'd charged the NiMHs in a fast charger: the cells still work, but they won't last as long as ones that've been well taken care of.

    As for using a timer, that's not a bad idea. In fact, the cheapo chargers than much of the world uses use a simple timer-based circut; they don't bother monitoring anything except whether there's something in the battery bay that passes current. However, this causes problems: if the charger or battery is malfunctioning, then it can zap a good battery, or pump too much current into a faulty battery and perhaps even cause a fire hazard. Most of the "smart" chargers are intelligent enough to detect faults in their own circutry and in the battery and will refuse to charge if things don't look right (like, say, the battery is passing 2000 mA). Using a timer is a good solution if for some reason you can't use any other charger, but I'd be in the market for a new smart charger if I just had a NiCD charger and lamp timer.

    Overcharging is one of the fastest ways to kill any rechargable, be it NiCD, NiMH, LiIon, Pb-Acid, or anything exotic. As long as you're careful, however, overcharging can be avoided fairly easily.

  • by Rolo Tomasi (538414) on Tuesday July 29, 2003 @07:04PM (#6565507) Homepage Journal
    Highest cap currently available are the Ansmann 2200mAh [digibattery.co.uk].
  • by gidds (56397) <slashdot AT gidds DOT me DOT uk> on Tuesday July 29, 2003 @07:15PM (#6565577) Homepage
    I was just going to mention these.

    Their characteristics are very different from other types of rechargeables. Alkalines have no memory effect -- in fact, they like being recharged from part-full, and last much longer this way than if fully discharged.

    So whether they're suitable depends very much on how you use them. I use them in my handheld computer; I set the battery monitor to remind me when they get below about half-way. This works really well; it means that I get plenty of warning to change them, and don't get caught out with flat batteries. Also, alkaline batteries generally have a larger capacity than other rechargeable types, and can be much cheaper.

    OTOH, they're not so good for devices which need a very long battery life, or which don't give any indication of battery charge. You can also get problems with some types of battery leaking slightly when recharged -- I haven't found this dangerous, but it can corrode the recharger's terminals slightly, leading to contact problems.

    In short: well worth trying if your intended usage is suitable. Oh, and pretty much any alkaline batteries are suitable, not just the Rayovacs. (I know Duracell, Energizer, EverReady &c claim they're not rechargeable, but then their sales would plummet if they did!) I find that the top-of-the-range Duracells are best; although the extra cost isn't really worth it if you're just using them once, for recharging they last for many more charge cycles, which makes them more economical in the long run.

  • Re:MOD PARENT DOWN (Score:3, Informative)

    by Jason1729 (561790) on Tuesday July 29, 2003 @07:18PM (#6565605)
    What do you think you're talking about?

    The datasheet is right here [energizer.com] for NiMH. That is a very flat horizontal curve until the cliff right at the end. For comparison, the Alkaline curve is here (look on page 2) [energizer.com]. That curve drops steadily throughout the life.

    Jason
    ProfQuotes [profquotes.com]
  • Avoid fast chargers (Score:1, Informative)

    by Anonymous Coward on Tuesday July 29, 2003 @07:20PM (#6565622)
    Fast charging is dangerous and shortens cells life. The Delta-V or Delta-T sensing models must be very well designed or they will destroy your batteries.
    I recently purchased a Vanson V6988 charger: too late I discovered that this piece of crap can't do slow charges, plus, it simply fails to detect the end of charge voltage dip on about 70% of all the cells I try to charge with it, thus keeping them on charge for extra long times and overheating them as hell.
    All cells are almost new and get fully charged in a good ol' c/10 slow charger.

    Get a slow charger, and more batteries if you need them often.
  • by Anonymous Coward on Tuesday July 29, 2003 @07:23PM (#6565646)
    go to http://www.imaging-resource.com/ACCS/BATTS/BATTS.H TM [imaging-resource.com] for a quite good review of nimh's and an explanation. informative, scientific, extensive, etc.
  • Re:NiMH (Score:2, Informative)

    by forevermore (582201) on Tuesday July 29, 2003 @07:28PM (#6565701) Homepage
    NiMH batteries are great but they have the downside of losing charge very quickly "on the shelf"

    You must be joking. I have a pile of panasonic NiMH batteries that I got at costco a couple of years ago. I keep a couple of spare sets in my camera bag for my flash, and they've kept a full charge for over a year.

  • Re:Recycle (Score:4, Informative)

    by TClevenger (252206) on Tuesday July 29, 2003 @07:38PM (#6565781)
    Radio Shack sends their dead rechargeables out to RBRC [rbrc.org] for recycling. RBRC will take any NiCD, NiMH or LiIon battery or battery pack (and lead-acid batteries up to 2 pounds.) Beats putting cadmium into the environment.
  • Re:A few tips (Score:2, Informative)

    by automatix (664568) on Tuesday July 29, 2003 @07:45PM (#6565866) Homepage
    When you buy batteries, look at the milliamp-hour rating. That's the capacity they can hold: for example, an 1800 mAh AA could supply (theoretically) 1 mA for 1800 hours, 1800 mA for one hour, or anything in between. While mAh ratings do tend to be stretched a bit (the tests are performed under the most favorable circumstances possible), it's the best guide you can get to how long the battery will last in the device you plan to use.

    Actually, it doesn't neccessarily mean that. It means it can supply a nominal amount of current (specified by the manufacturer) for a nominal number of hours... which happen to multiply to 1800. You will never ever get 1800 hours or 1.8A for an hour... For example, from my handy databook Panasonic says their mAh ratings for NiMH batteries are at a discharge of 0.2C (C=battery rating in mAh). So a 1800mAh NiMH is only 1600mAh at a discharge rate of 360mA (ie. it will last 5 hours).

    It is till the best guide for battery capacity though...

    One other tip - NiMH batteries only generally last a maximum of 2 years or 500 cycles. So when they get that old, you've saved yourself tonnes of money already - just recycle them and get new ones rather than trying to bleed every last bit out of them...

  • RipVan100 (Score:3, Informative)

    by McCart42 (207315) on Tuesday July 29, 2003 @07:51PM (#6565928) Homepage
    I'm a big fan of the products sold by RipVan100 [ripvan100.com]. I first happened upon them when looking for batteries and a charger for my new digital camera, and since they seemed to rank pretty highly in reviews [imaging-resource.com], I decided to buy them.

    I still have the green Sanyo "industrial grade" cells I originally bought about 2 years ago, and I've been buying more since for other purposes. The charger (lightning pack 4000) is also excellent. I can't necessarily recommend the newer batteries they've stocked, but I definitely recommend the charger and the green-jacketed Sanyo batteries - they consistently perform well for me, and most reviews note that they perform BETTER than several NiMH battery brands with higher mAh numbers (they're only 1700 mAh).

  • by Glonoinha (587375) on Tuesday July 29, 2003 @08:09PM (#6566091) Journal
    -I have an AA factor LiIon battery that puts out 3.6V for 2500 mAH.

    Umm the standard for the AA sized battery is 1.5v - you go sticking batteries that put out two and a half times the expected voltage into sensitive devices and they will .. I dunno, maybe not like it.

    I do like LiIon batteries, although I have never used them in the AA form factor (just in laptops.)
  • by Anonymous Coward on Tuesday July 29, 2003 @08:14PM (#6566129)
    Standard disposeable alkaline batteries have very good capacities but also high internal resistances, so they don't do well in high-drain applications.

    NiCD batteries have lower capacities than alkaline, but they have miniscule internal resistance and can push an unbelievable amount of current. I'm getting about 45 amps of current from 1700 mAh NiCD battery packs in one of my RC planes. These batteries deliver close to 100% of their rated capacity even at insane drain levels like this. Downside to NiCD's is that they discharge at about 1%/day, so they are useless for stuff like clocks and calculators, etc.

    NiMH have almost the same capacity as alkaline and almost the same internal resistances as NiCD. They are sure to replace NiCD since some new high-drain types can equal NiCD performance. These also self-discharge pretty fast.

    Li-Ion are a completely different chemistry. Alkalines push 1.5v/cell. NiCD and NiMh push 1.2v/cell, which is close enough for drop-in replacements. Li-Ions are 3.6v/cell, so they are not really practical in replacing 1.5v alkalines. Li-Ions oxidize over time, so they lose capacity. Useful life for something like a laptop battery is 2-3 years or somewhere around 300 cycles. Li-Ions lose efficiency very fast as current draw increases.

    So, to sum things up:
    In clocks, calculators, smoke detectors and other long-run, low-current devices, use alkalines.

    In high drain devices like digital cameras, flashlights, electric motors, NiMH are probably the best bet.

    For insane current draw, use NiCD. Sanyo R-cells can push > 100 amps!

    Use lithium only in devices designed for it. A NiMh/NiCD charger can and will explode a Li-ion.

    Good luck.
  • by dann0 (555381) on Tuesday July 29, 2003 @08:25PM (#6566214)
    Is operating temperature a concern? NiMH batteries are not so good in low temperatures, so don't use them in a GPS on your Everest Expedition.

    What about space/weight/charge density? Lithium Ion batteries have a higher energy density than NiMH and NiCads, but they require more intelligent (read: expensive) chargers, as they are often microprocesser controlled.

    Current Drain? NiCads can deliver more current than NiMH batteries.

    Access to power supply? Weight and size of chargers? NiCad batteries are the easiest (after Lead Acid) to recharge, so the charger could be lowcost and small sized. You can charge a NiCad quite well with just a dc power supply and an appropriate voltage dropping resistor, just make sure that you time the charging to match the capacity. You can't jury-rig chargers for Li Ion batteries and you have to be very careful for NiMH cells (you really need to detect the voltage drop these guys display when nearing charge completion and trickle charge from that point onwards).

    Also, contrary to what others have posted, not all batteries of the same kind are created equal. Stick to name brands (Sanyo batteries have been very good for us) - they tend to last a little longer. Maybe they have more pure electrolyte or electrodes?

    Avoid rechargable alkalines. It will end in tears.

    Good luck with your decision.
  • NiMH == all the same (Score:5, Informative)

    by wcdw (179126) on Tuesday July 29, 2003 @08:37PM (#6566294) Homepage
    A great deal of the raw materials for NiMH batteries comes from China (and Russia), regardless of what the "made in ..." sticker says. (See http://ovonics.com [ECD, the NiMH patent holder] for more info.)

    So, if you buy NiMH, you don't have a lot of choice in the matter. This is NOT to suggest avoiding NiMH, which is a superior battery in many situations - just to inject a note of realism.

    As for the original poster's question, surely there is a website out there with vast amounts of statistical data on the various brands (and types!) of batteries?

    I like NiMH as it is relatively easy (and safe) to recycle. However, keep in mind that NiMH can lose up to 2% of its charge per day sitting on the shelf. NOT a good choice for that emergency flashlight. :)
  • Re:NiMH (Score:2, Informative)

    by johneee (626549) on Tuesday July 29, 2003 @08:37PM (#6566301)

    For consumer batteries in conventional form factors (AA, AAA, C, D & whatever a 9-volt is called)


    They're called 9v batteries. And the other ones on your list aren't batteries, they're cells. A battery is a collection of cells.

    So a 9v battery has 6 1.5v cells in it.

    Is it any wonder my wife calls me Mr. Pedantic?
  • by Myself (57572) on Tuesday July 29, 2003 @09:04PM (#6566528) Journal
    One thing I've heard is that lower amp-hour batteries are actually BETTER in some applications. In increasing the electrode surface area that goes into a battery, manufacturers encounter a tradeoff with reliability, internal resistance, and longevity.

    A lower capacity cell will have thicker electrodes, which conduct more easily and will last through more charge/discharge cycles. Ideal for applications like camera-flash units that draw very heavy current. You'll just have to charge them more frequently.

    The higher-capacity cells would be more suitable for low-drain devices, like portable music players, or cameras that don't see much flash use. Their higher internal resistance doesn't pose a problem when the power draw is low.

    Another thing to be aware of is that many chargers go into a blitz charging mode on startup, blasting heavy current into the batteries for the first hour, before backing off, taking a reading, and determining how much further charging is needed. This makes sense if the charger is plugged in constantly, and only drained batteries are tossed into it. It only becomes a problem in situations like mine: I was running a little 4xAA charger from the inverter in my vehicle, which would cycle on and off with the engine. Leaving batteries in the charger would cause them to get blasted every time I turned the car on, shortening their life dramatically. Don't do that. Now before I shut off the engine, I peek at the charger to see if it says they're charged. If so, I take them out and toss 'em in a cupholder, so they don't have to endure further charging. Keeping a spare set in my vehicle has proven indispensable though.

    Avoid Rayovac. I got a Rayovac "3 in 1" desktop charger, which advertises the ability to charge NiCd, NMH, and rechargeable alkalines. Then I threw in a set of four Rayovac NMH AA's. A few hours later, I discovered that they'd gotten so hot during charging, their labels had warped and peeled, exposing the bare metal can underneath. They still work fine, holding plenty of charge to be useful, but the bare metal means I can't use them in certain devices' battery compartments because of shorting concerns. I put a set of ancient Radio Shack NiCd's in it, and it cooked them too. They were probably dead anyway, but the point is, the Rayovac charger doesn't have a thermal cutoff, which it should! Curiously, this charger works just fine on my other batteries, even AAA's never get more than warm during charging.

    Ironically enough, another set of Radio Shack "high capacity" NiCd AA's from the same era work just fine, in the Rayovac charger and others. Because the NiCd chemistry has a lower self-discharge than NMH, they're ideal for occasional-use standby duty. Those old cells sit in my Mag Lite.

    Really, for standby jobs, the best chemistry is rechargeable Alkaline. They have almost no self-discharge, so they can sit for months on end and still be ready for service. I've got a pair of Renewal AAA's in my laser pointer, I think I've charged them 5 times in the 5 years I've owned them. (BTW, it's worth the extra bucks for a laser that takes standard batteries. After you've replaced those button cells 2 or 3 times, you begin to see why.)

    You should check out Isidor Buchmann's excellent book [buchmann.ca] on the subject. After a free "who are you?" registration, you can read the whole thing on line.

    P.S. Anyone know an outfit that rebuilds Lithium-ion laptop batteries?
  • by matt-fu (96262) on Tuesday July 29, 2003 @09:07PM (#6566558)
    I know you're being sarcastic but..

    4) Actually, you need a "push mower" like the old days. Save money and slim that fat ass of yours.

    Actually, I have a "push mower" (it's called a reel mower [cleanairgardening.com]) like the old days. It's actually lighter to push around than a regular gas mower since there's no engine, with the added benefit of getting to experience the "fresh cut grass smell" the entire time rather than only after you're finished. The only downside is that you can't let your lawn get out of control. You have to keep up with it because the mower won't cut grass that's longer than four inches or so.

  • EZONE! (Score:5, Informative)

    by g00bd0g (255836) on Tuesday July 29, 2003 @09:21PM (#6566663) Homepage
    More than you ever wanted to know about battery tech. Keep an eye on the emerging Lithium Polymer batteries @ roughly 3X the current NiCd and NiMh power/weight and power/size batteries. I use them in my micro R/C helicopter instead of the oringal NiMh and get 3X the run (was 5 now 15 minutes) with less than 1/2 the original battery weight (1.75oz vs 3.75oz). These are gonna be cost effective in the next 10 years or so, making a 100 mile range EV very easy and cheap. This is what they are using in the current solar racers. Environmentally friendly as well! Oh the original question? 2000mah NiMh all the way.
  • My battery history (Score:2, Informative)

    by sk8king (573108) on Tuesday July 29, 2003 @09:30PM (#6566717)
    My charger: Rayovac PS3
    Great because it charges rechargeable alkaline, NiMH, and NiCd [not 9Volt form factors, but the standard AAA, AA, C and D batteries] and it won't overcharge them.

    I have three or 4 pairs of NiMH for my digital camera [works great in there] and Talkabout radios. Have a couple sets of rechargeable alkalines for stuff like remote controls [long idle time in those]. Don't have any NiCd...too many problems with battery memory which the NiMH doesn't have.

    The best battery I've seen was the Kodak Lithium Ion 3V [single battery in the form factor of two AA's]. It ran the camera for three months before I replaced it with the rechargeable NiMH.

    Just my $0.02
  • by buttahead (266220) <tscanlan.sosaith@org> on Tuesday July 29, 2003 @09:42PM (#6566790) Homepage
    According to a very long article/discussion I read somewhere (sorry, can't remember the URL), NiCd batteries are easily damaged by overcharging, which tends to reduce their capacity over the life of the battery - and there is no so-called "memory effect".

    I'm not sure about over charging, but they used to have problems with filing to get a full charge if used before they were fully charged. This has been fixed in the last couple years, though.
  • by ball-lightning (594495) <spi131313@yahoo.com> on Tuesday July 29, 2003 @10:00PM (#6566908)
    Why is this modded funny? There really is [crutchfield.com] a monster brand of battery.
  • More on "memory" (Score:4, Informative)

    by Daniel Rutter (126873) <dan@dansdata.com> on Tuesday July 29, 2003 @10:08PM (#6566961) Homepage
    Someone's already linked [slashdot.org] to one of my pieces about batteries, so I need only pimp Dan's Quick Guide to Memory Effect, You Idiots [dansdata.com] :-).
  • Re:NiMH (Score:1, Informative)

    by Anonymous Coward on Tuesday July 29, 2003 @10:09PM (#6566972)
    A little clarification: NiMHs lose about 10% of their charge per month on the shelf. But the shelf life isn't the biggest concern with trickle chargers readily available.

    Because of the short shelf life, NiMHs are best used in high-drain devices like digital cameras, GPS receivers, cel phones, etc. They are _not_ good for things like TV remote controls and clocks that don't use much power because you lose more power to leakage than to the device. In these applications, good old-fashioned NiCds work better.

    Lithium-ion batteries pack a punch, but they're expensive, and they require external circuitry to prevent overcharging, as overcharged Li-ion batteries tend to explode. For this reason, they tend to be used only in special applications. In the consumer world, they are most commonly used by hobbyists in custom RC cars and airplanes.

    Lithium polymer batteries are a step above Li-ion. They don't require the extra circuitry, they're very light-weight, and they can be made in almost any shape and size. They don't even need a metal case. They more often resemble a bag full of jelly! But because of their high price, they are very uncommon in consumer applications. However, I expect we'll see more Li-polymers appearing in weight-critical applications in upcoming years...such as in electric cars and bicycles.

    -- A battery enthusiast
  • Re:NiMH (Score:3, Informative)

    by crapulent (598941) on Tuesday July 29, 2003 @10:10PM (#6566975)
    That means the voltage of the battery should be at least double the voltage drop of the LED.

    Not if you want decent battery life, it shouldn't.

    I think you'll find most "advanced" LED flashlights use a small PIC and utilize PWM to regulate the LED current rather than wastefully throwing away any battery voltage in excess of the LED's forward voltage.

    And if they don't use a microcontroller, they use a battery arrangement as close to the forward voltage of the LED so as to maximize available life.

    In other words, in such an application it's fine if the LED current varies significantly over the discharge of the battery, because it means a much longer usable overall battery life.

    For reference, I have a Photon Micro-Light (a popular brand of small LED flashlight) which uses no resistor (or PWM) whatsoever. Just two watch batteries in series connected directly across the LED.

  • by Chambers81 (613839) on Tuesday July 29, 2003 @10:27PM (#6567085)
    There really isn't much copper. A fun way to test it was given in a high school chem class, where we cut a notch out of the penny's side, then put it in an acid bath over the weekend. When we washed the thing off, all the zinc inside had been eaten out by the acid, leaving an extremely thin copper outside. One of the few things i remember from then, other than making ice cream and blowing things up when the teacher left the room.
  • by axelbaker (167936) on Tuesday July 29, 2003 @10:49PM (#6567229)
    Panasonic is (as far as i know) the largest maker of battery cells in the market. They make excellent LiO and NiMH cells. NiMH are probably the best bang for the buck, as they are a direct replacement for regular alkaline batteries. Lithium are great if they will work in our device as they are lighter, and wont be destroyed if you accidentally let them heat up or get too cold. Down side is LiO cost a lot more.
  • by Dr. Zowie (109983) * <slashdot@defores[ ]rg ['t.o' in gap]> on Tuesday July 29, 2003 @10:56PM (#6567261)
    I discovered 'em recently, and bought 12 of the AAs for an old Logitech cordless optical mouse and keyboard setup that can't run off NiCds (1.3 volts) or NiMHs (1.2 volts). (4 in the keyboard, 2 in the mouse; 2x for continuous use).

    I liked 'em so much I went back to Target to find more and discovered that they're not carried there anymore. Nor at Radio Schlock. Nor at a bazillion other places. I think Ray O Vac is trying to phase them out.

    It's too bad -- rechargeable alkalines do something the others don't: last a long time in the drawer. It takes years for an RA to self-discharge; about 30 days for a NiCd.
    (The upshot is that any NiCd you don't store in a a charger is empty when you actually want it).

  • by CustomDesigned (250089) on Tuesday July 29, 2003 @11:01PM (#6567291) Homepage Journal
    I bought some rechargeable alkaline batteries and a charger. They recharged a few times, then leaked. Since the whole reason to pay a premium for rechargeable alkaline was that they wouldn't leak like regular alkaline, I put some regular alkaline batteries in the charger. They might leak a little more often than officially rechargeable, but not much.

    So now I just buy regular alkaline and recharge them until they start leaking, then throw them out. Recharging before deep discharge gives the longest battery life for alkaline. I had a set in my RC car that I recharged after every play session, and they lasted for two years (with several sessions a month).

    If batteries leak badly, I clean up the discharge with white vinegar and baking soda.

  • by Anonymous Coward on Tuesday July 29, 2003 @11:06PM (#6567330)
    Also, Taiwan is the Chinese nationalists. Taiwan != China.

    Actually, Taiwan == China, though not Taiwan === China. Just about any thing made in Taiwan (especially steel products) are actually made in PRC then finished in Taiwan. For decades most companies in Taiwan have shipped as many factories as they could across to providences in China. Their labor is extremely cheap, the government is willing to let them do about anything, and the Taiwanese gov't is pretty lax in country of origin decisions. So in this case, the batteries are likely made in PRC and then painted (if that) and packaged in Taiwan.

  • by Keebler71 (520908) on Tuesday July 29, 2003 @11:41PM (#6567549) Journal
    I don't have feelings either way for Dan Quayle, but since no one will stick up for him, I will at least point out an important fact that is usually left out when this story is told... that the word "potato" was incorrectly spelled on the question cards that he had been given by the school for the spelling bee. He had also been assured that they had been checked and were all correct. Granted, he still did not recognize that the word was mispelled but at least you are a little more informed.
  • by morekicks (570114) on Wednesday July 30, 2003 @01:26AM (#6568105) Homepage
    us citicens use twice as much energy per caput as europeans not to speak of china, russioa or other countries resulting in the highes co2 emissions worldwide. (http://www.natenergy.org.uk/co2mment.htm) us citicens seem to think using more fuel, ignoring the kioto protocol and pushing their own oil industry (now to be seen in irak) is the right way to treat this planet. let's face it - you are the pigs of this planet! and this is ment in orwells's words as well as mom's.
  • by TygerFish (176957) on Wednesday July 30, 2003 @06:56AM (#6569283)
    This might be a little 'late-in-the-day,' but here's a mini-article on rechargeable batteries.

    With industry claiming that one set of rechargeable double-A batteries can be charged up to 1000 times, even before you consider the environmental impact of switching to rechargeable batteries, the economic arguments for using them are very convincing.

    In my experience, a set of current generation rechargeables cost no more than two to three times what a set of comparable quality disposable batteries do and even if the advertiser's claims with regard to the number of recharging cycles are wild lies--exaggerated by a factor of one hundred--you *STILL* make out like a bandit by using them. As far as I'm concerned, they're the smartest thing going.

    Down to brass facts, or, 'more than you ever wanted to know...'

    Current rechargeable batteries are an imperfect technological compromise between alkaline batteries and cheaper disposable battery technologies. As such, you find that even the best rechargeables tend to be somewhat underpowered in terms of the voltages they generate. Disposable and recharable double-A batteries share form factors, but the rechargeable is designed to sustain a slightly lower voltage than the disposeable--when you read the fine print on a sampling of rechargeable double-A's, you find that nearly all of them are rated for 1.25 volts instead of the disposable's 1.5---and in some applications requiring a higher voltage, rechargeables might not be all they're cracked up to be. Personally, I have never seen this to be the case.

    For a lot of people who thought about buying rechargeables years ago and rejected the idea, one of the things that put them off was having to charge their batteries all night for units that didn't have anything like the stamina of disposables. This is simply no longer true. Rapid chargers are available from a number of well-recognized companies which will rapidly impart an almost full charge to them, often in as little as one to two hours.

    The stamina of rechargeables has also improved over the last few years. Rechargeable batteries are rated according to their maker's claim that their batteries will put out useful voltage over time. This is measured in thousandths of an Ampere per hour (aka, milliampere hours, sometimes abbreviated, mAh) with the number of mAh forming the cornerstone of the company's marketing efforts. In theory, the greater the number of mAh on the battery's label, the longer it will last in high-drain devices like digital cameras, where rechargeables are pretty much imperative if you want to avoid going broke while you poison the local groundwater.

    Back in the bad old days, rechargeable batteries were nasty beasts with little to offer. You had to be organized and disciplined to use them. They were expensive. They took all night to charge and compared to a set of Duracells alkalines, they were bad joke. All of that has changed. I use rechargeables exclusively in applications ranging from my portable reading lamp to my digital camera and I couldn't be happier.

    Names to look out for at your local electronics outlet include, Sony (more for their charger than their batteries), Duracell, and Power2000, who have just come out with a double-A battery that they claim offers a 2100 mAh of power, which, if true, put them at the top of the heap.

    Happy trails.
  • by Anonymous Coward on Wednesday July 30, 2003 @07:39AM (#6569391)
    Here's the reality of what your little boycotts could ruin.

    http://www.lewrockwell.com/spectator/spec79.html [lewrockwell.com]
  • by stekman (575167) <stekman@NOsPam.sedata.org> on Wednesday July 30, 2003 @08:33AM (#6569626) Homepage
    The amount of water used in the process of makeing diapers exceeds the amout of water when you wash diapers (if you fill the machine up). The a weight of garbage from one average kid using diapers is 1000kg. The energy from transporting the garbage, makeing the diapers and transporting the diapers to the shop exeeds the energy to clean the diapers by serveral times. An average kid uses 5000diapers. That is about $1500. A set of cloth diapers costs about $35. We have used cloth diapers for both our girls. It was really good and as they feel that they are wet when they pee, they stopped using diapers a lot sooner then the other kids at kindergarden.
  • by Andy Dodd (701) <[atd7] [at] [cornell.edu]> on Wednesday July 30, 2003 @08:58AM (#6569755) Homepage
    Most accounts I've seen on www.candlepowerforums.com call the Rayovac charger a "pressure cooker" and is voted Most Likely To Destroy Your Batteries.

    People there are big fans of Maha chargers. They just released one that has an individual charge controller for each cell, which means that you can charge non-matched batteries safely, AND you don't have to charge 2 or 4 at a time - You can charge 1 or 3 if you wish.

    As to the types of batteries out there:
    Alkaline - Reasonably long shelf life, high internal resistance. Good for low-current applications like TV remotes and HP48 calculators. Gentle discharge curve.

    NiCd - Toxic, lowest capacity rechargeables. Lowest internal resistance, which is why they're still popular in R/C cars because of their insane current handling capabilities. Flat discharge curve with a steep dropoff at the end.

    NiMH - Almost identical to NiCd except non-toxic, double the capacity, and somewhat increased internal resistance. Excellent for medium to high-discharge-rate devices such as CD players and digital cameras. Same basic charging algorithm as NiCds, although the charger must be aware of minor differences between NiCd and NiMH batteries. Both will actually start DROPPING their voltage as they are charged beyond capacity. Modern smart chargers detect this, but the peak and subsequent drop are much smaller with NiMH, requiring a more sensitive charger.

    Lithium - Extremely high capacity, current handling capability, and the longest shelf life. Most are 3v, although I've seen 1.5v "Lithium" AAs (might not actually be lithium.) Non-rechargeable
    Lithium Ion - Rechargeable, high capacity, high current handling ability. Very lightweight. Unfortunately quite flammable. Between the low internal resistance and flammability, it is not legal to sell bare Li-Ion cells in the U.S. to someone not licensed to work with Li-Ions. Almost anyone you buy "cells" from in the U.S. (such as www.onlybatteries.com) indicates that the cells are sold in a pack with some sort of protection circuitry if you read the fine print. (This circuitry cuts off the battery if a short circuit is detected, preventing the batteries from exploding.)

    Lead-Acid - An oldie but goodie. Highest energy density per unit volume, but horrible density per unit weight. DIRT CHEAP. Still used when enormous capacity and current handling ability is needed at minimal cost. (Read: Car batteries.) A number of variants exist. Standard car batteries have very thin electrodes designed to maximize surface area for maximum current handling ability. These types don't like being discharged very deeply. "Deep cycle" cells have thicker electrodes, allowing them to be cycled more deeply but with less current capacity. (Still quite a bit, and nowhere near as deep as any other rechargeable chemistry.) "Gel cells" are a deep-cycle variant that uses a gelled electrolyte. These are much safer and can be sealed, which makes them optimum for situations where the battery might get wet or tipped over. (Automotive lead-acids are vented and cannot be safely tipped over.)
  • by macwhiz (134202) on Wednesday July 30, 2003 @09:28AM (#6569985)

    The majority of "generic" non-rechargeable batteries sold in the U.S. are made by the same "major" manufacturers. Unless the ink used to print the brand name on the battery is somehow causing a performance increase, any apparent performance improvement is probably due to good advertising.

    However, among the major manufacturers (and therefore also among the brands of "generic" battery they OEM), there are differences in construction that make some batteries better for some tasks than others.

    While working at Kodak, I found that Kodak's Supralife AAA batteries lasted noticeably longer in my Palm than Duracell or Energizer. When I installed a program that tracked battery voltage, I found that the Supralife batteries' voltage declined in a very predictable curve, where Duracell and Energizer tended to fluctuate, sometimes causing the Palm to decide the batteries were near death when they still had useful life. This was several years ago, and the battery formulations may have changed.

    The best advice with disposable batteries is: try a few different brands and find out what works best among the brands in your area, in your device, the way you use it.

  • by barawn (25691) on Wednesday July 30, 2003 @10:17AM (#6570315) Homepage
    Alkaline rechargeables are 1.5V. NiMH rechargeables are 1.2V. They hold their charge better than Alkalines, of course (until they run dead, when their voltage drops to 0 very fast). This is, of course, important, as 2 NiMH rechargeables in series gives 2.4V, and 2 alkalines in series gives 3V (i.e. CMOS 3.3V).

    Many people don't know that electronics that says "don't use rechargeable batteries", it's because of the voltage. In those, you're fine using alkaline rechargeables.

    In many cases you can use NiMH rechargeables and it'll work fine. Electronics is remarkably tolerant to low voltage levels. However, if you read your warranty on many of those devices, you'll find that you void it if you use rechargeable NiMH batteries. With rechargeable alkalines, you don't need to worry at all. It also makes the "battery meter" on electronics work correctly, say, on a Game Boy Advance, where the LED goes from Green to Red at about 1.35V, and then off completely by 1.2V. Rechargeable alkalines show normal behavior. Palm Pilots as well, though Palms can change their battery meter to read NiMH rechargeables.

    And don't get me started that NiMH rechargeables lose charge over time by bleed away, and alkalines don't. So NiMH batteries are useless if you want to just leave them in something for a while.

    Short answer: Rechargeable alkalines have several advantages over NiMH, which is why you can still buy alkaline rechargeables. NiMH is almost purely better than NiCad, which is why you can't buy NiCad much anymore (plus I think NiMH is friendlier to dispose of).

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