Rechargeable Batteries - Yes or No? 896
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?"
Save the environment.. (Score:5, Funny)
Re:Save the environment.. (Score:5, Funny)
Let's sing a song... (Score:5, Funny)
Screw the environment you posers (Score:5, Insightful)
Hell, if you want to reduce your impact on the environment, try a few other sacrifices:
1) Adopt instead of breed.
You might as well adopt one if you plan on having kids (at least as ONE of them). If you don't feel adoption is your civic duty, they'll just accumulate and become a local nuisance. Then you'll need to pool your money with local businessmen, and hire off-duty cops to "clean up" the problem.
2) "Disposable diapers"
Need I say more?
3) Of course... don't expect a woman to give up this convenience while you parade around in a HumVee and a mow your lawn with a 20hp rider tractor. Otherwise you're forcing the burden on someone else.
4) Actually, you need a "push mower" like the old days. Save money and slim that fat ass of yours.
5) Lawn?? Plant a fucking tree you egotistical prick. You can still plant grass that's not harmful to the environment... it's called NATIVE grass. You'll not find it at the nearest local golf course...
6) Trees mean you don't need to water your lawn.
7) Or CHEM-LAWN(tm)
Actually, if you're stupid enough to lay toxic chemicals on your lawn, you have penis-size issues.
8) Don't listen to me... you'll end up spending more money on viagra...
Moderators: If the above ON TOPIC SARCASM offends your sensibilities, go ahead and mark me as Flamebait or Offtopic. The meta moderators will get you...
I know some of you will agree though
Re:Screw the environment you posers (Score:3, Informative)
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:Screw the environment you posers (Score:5, Informative)
Re:Screw the environment you posers (Score:5, Funny)
Re:Screw the environment you posers (Score:5, Informative)
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.
Re:Save the environment.. (Score:5, Interesting)
Re:Save the environment.. (Score:4, Interesting)
For the record, in 1982 the penny was changed from 95%Cu/5%Zn to 97.5%Zn/2.5%Cu (the copper being a thin cladding on the outside). The weight changed from 3.11g to 2.5g. If you scratch a modern penny, you can see the shiny silver zinc under the copper cladding.
Interesting bit of trivia: The old and new pennies sound very different when dropped onto a hard surface: the old ones have a bright ring; the new ones are considerably duller in tone. You can sort them by sound!
I use monster brand (Score:5, Funny)
EZONE! (Score:5, Informative)
Re:I use monster brand (Score:4, Informative)
Re:All About the Same (Score:5, Insightful)
Re:All About the Same (Score:5, Insightful)
Re:Actually WalMart is excellent (Score:5, Interesting)
Yup. They save money on their suppliers. But never would they think to do so on their employees, no
Re:Actually WalMart is excellent (Score:4, Insightful)
Do you see that your tax dollars go to enable Sprawl which in turn makes helps walmart mark "low prices"... "low prices" indeed.
this says nothing of pollution and habitat loss...
ive never spent a dime at walmart, and it *does* make me a better person.
Taiwan??? (Score:4, Insightful)
Re:All About the Same (Score:3, Insightful)
Re:All About the Same (Score:5, Insightful)
Hmm...
do I patronise the Chinese manufaturer so that their employees can eat?
or do I patronise the American manufacturer so that their employess can buy A BIG SCREEN TV's at AL's TV EMPORIUM - SUNDAY SYNDAY SYNDAY - Save BIG at AL's on SUNDAY. Free hot-dogs, and baloons for the kiddies!.
Re:All About the Same (Score:4, Insightful)
You don't support American Multinationals working out of foreign countries because it's colonialism, economic albeit - but the same difference.
Go read No Logo by Naomi Klein [nologo.org].
For the most part, multinationals working out of Economic Protection Zones (EPZ's) attempt to get the highest rate of young girls from the countryside to work for them. This allows them to::: treat their workers like shit, pay them little, threaten them easily if they try to unionize, etc etc. - all leading to poor working conditions wherein the girls feel threatened and scared, wherein the girls feel they _have_ to keep working and sending piddly change home to mom and pop, all the while suffering so we can get Gap shirts [behindthelabel.org] and all sorts of consumerist b.s. for as cheap as possible [sweatshops.org].
So no, you are not supporting the Chinese. You are bringing them into economic slavery [maketradefair.org]... Chinese gov't loves it.. the jobs bring in technology profit - but for the workers it is not an advancement [maketradefair.com].
Go read Small is Beautiful by E.F. Shumacher [www.sfu.ca] to see how I think one should work to bring the Third World to a good standard of living.
And as if they dude in the battery factory in the U.S. is living the large life. Give me a break. At least he may have a proper working environment where he is safe, he doesn't work his ass of for jackshit, and he may even be able to join one of those union thingies.
Too bad sweatshops are on Big Al's T.V.
Re:All About the Same (Score:4, Insightful)
Re:All About the Same (Score:4, Funny)
Re:All About the Same (Score:5, Interesting)
Bullshit. First, there are different kinds of rechargeables -- NiCd, NiMh, Lithium, to name a few most widespread. Their characteristics are quite different. Second, as usual you typically get what you pay for.
But not buying batteries from an electronics store is good advice. They are horribly overpriced there, any brand...
Rechargeable batteries, like toothpaste, is a commodity product.
Toothpaste? You mean you alway buy the cheapest toothpaste you can find??
When you buy a product, you indirectly support the value system in the country of origin.
I do? How interesting... Is it one of those "if you do drugs you support terrorism" rants?
"Made in USA", "Made in Japan", or similar Western-country label is usually a safe bet in terms of (1) the quality of the product and (2) the value system in the country of origin.
Thanks for a good laugh... To start with, Japan is not a Western country. To continue, US produces large amounts of very shoddy products. "Made in USA" is definitely not a guarantee of quality. And what was it about value system again?
Re:All About the Same (Score:5, Interesting)
I've had very good luck with Ray-O-Vac. Ray-O-Vac also makes higher capacity line of NiMH batteries than other manufacturers (check the labels for the mAh rating).
NiMH == all the same (Score:5, Informative)
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.
NiMH (Score:4, Interesting)
Re:NiMH (Score:5, Informative)
Re:NiMH (Score:5, Funny)
Is that the "Secret of NiMH"?
Re:NiMH (Score:5, Funny)
I smell a rat...
Comparison of various batteries. (Score:5, Informative)
Re:NiMH (Score:5, Insightful)
This is not the case in my experience. I have used 650mAh AAA NiMH batteries with my Palm IIIx for about three years now. I have two sets of batteries (so one can recharge while still using the old set) and when travelling for long periods of time (several months) I've just charged both sets and used the second set a month later. There was a small loss of charge, but it wasn't a big deal.
Sure, you can't charge the things up and leave them for half a year. But when are you ever going to need to do that? In the very worst case scenario, you could always pack a travel charger - they're small and light.
I don't think I could begin to count the money I've saved by not having to change two sets of Alkaline AAAs each month (well, actually I could - it's several hundred dollars as opposed to an initial outlay of $40 for the batteries and the charger). And the capacity of NiMH batteries keeps getting better - you can now get 650mAh AAAs and 1850mAh AAs just about everywhere, which is a huge improvement on rechargables five or ten years ago
Re:NiMH (Score:4, Informative)
Not every charger, actually. Check yours to learn wether it has this 'keep alive' feature.
Re:NiMH (Score:3, Informative)
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 comm
Re:NiMH (Score:4, Funny)
My son has lots of electronic toys, I fill all with rechargables. I put rechargables in anything that gets frequent use, and use standards in things that dont.
frequent use:
kids toys
pager
remote controls
vibrator
Rotating Tie-rack
non-frequent use:
smoke detector
battery-backups
Flashlight
You find Li batteries in equipment that tends to be charged daily. From the daily charge I highly suspect they don't hold charge too well, but they probably have high life cycles. Probably why they don't go in pagers and other stuff that does not have a built in charger.
Cordless telephones
cellular telephones
Cameras
computers
PDAs
Re:NiMH (Score:3, Informative)
Re:NiMH (Score:3, Informative)
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 ch
Re:NiMH (Score:4, Informative)
- 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.
- 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.
- 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:4, 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]
Re:NiMH (Score:5, Informative)
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.
Re:NiMH (Score:4, Funny)
Yep, NiCd cells can REALLY dump current. Ever short-circuit a fully charged NiCd just for grins? I did this one time, with a cell that came out of an old gadget of some kind. The cells were the kind with wires soldered to either end; I stripped the wire ends, twisted them together, then stood back to watch the fun. In no time, the insulation on the wire was smoking, then bubbling and melting off. But soon something happened I hadn't counted on: the solder on the battery tabs melted and the wires fell off. At this point, I decided maybe it wasn't such a smart experiment after all and I gave it up.
Re:NiMH (Score:3, Interesting)
I haven't seen these, since very old 12 V powered radios. They were used with the radios when alkalines were used. Normally 10, 1.2V NiCad AAs were used in the radios. If you used alkalines, you needed 8 1.5V AAs. To keep from hurting the radio, you used two of these AA shaped conductor blanks.
Re:NiMH (Score:5, Informative)
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).
Nickel Metal Hyride (Score:5, Informative)
Re:Nickel Metal Hyride (Score:5, Informative)
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:Nickel Metal Hyride (Score:4, Interesting)
Re:Nickel Metal Hyride (Score:5, Informative)
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:Nickel Metal Hyride (Score:5, Informative)
Re:Nickel Metal Hyride (Score:4, Informative)
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.
What about rechargable akaline? (Score:5, Interesting)
Moreover, they do have a distinct advantage: they're cheap and of high capacity, though not good for many recharge cycles. While a pair of Ni-MHs cost about $8, a pack of 4 rechargable akalines costs about the same price. Like regular akaline batteries, they have pretty high capacity (about 2200(I think) mAh for a AA, compared with the low 1000's range for most Ni-MHs), and actually come charged, with a long shelf life without discharging itself.
I use these batteries for most of the things that don't work with Ni-MH (graphing calculator, small electronic devices), as these have the usual 1.5 volt, instead of the 1.2 volt on most rechargables. Their downside is the fact that they can only be charged 10-20 times before they leak (the package said 40).
Re:What about rechargable akaline? (Score:4, Informative)
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:What about rechargable akaline? (Score:3, Informative)
Re: What about rechargable akaline? (Score:3, Informative)
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,
Re:Nickel Metal Hyride (Score:5, Funny)
Batteries (Score:5, Informative)
Those batteries keep their energy for 3 months at a time easily, when I am not on vacations or otherwise using the camera.
I like the rotational kinetic battery (Score:3, Funny)
Re:I like the rotational kinetic battery (Score:4, Funny)
The smallest I've seen of these are the size of large bucket - maybe about 2 gallon size.
Can't exactly put that in a wireless mouse, now, can we? Not to mention the gyroscopic effects of the battery in portable applications.
Re:I like the rotational kinetic battery (Score:3, Funny)
NiMH - accept no substitute. (Score:5, Informative)
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.
look for the rating. (Score:3, Informative)
Don't sweat it (Score:4, Insightful)
You want to make a difference? Drive an efficient car (if you must drive one at all) and recycle what you can.
Ray O Vac (Score:5, Informative)
Satisfying someone else... (Score:3, Funny)
My wife has this vibrating thing, something Rabbit, she's always saying it satisfies her...
lower impedance (Score:3, Interesting)
However, I have always ignored the above and never had any kit die as a result of using rechargables.
Re:lower impedance (Score:3, Informative)
Re:not to nit pick... (Score:3, Funny)
All kinds. (Score:4, Informative)
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:All kinds. (Score:3, Informative)
Recycle (Score:5, Informative)
Re:Recycle (Score:4, Informative)
iGo Juice (Score:4, Informative)
where is the CowboyNeil option... (Score:3, Funny)
[ ] CowboyNeil charges my battery
Walmart anyone? (Score:4, Informative)
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)
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)
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.
NiMH by far, and retrofittable to NiCad stuff (Score:5, Informative)
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.
Re:NiMH by far, and retrofittable to NiCad stuff (Score:3, Informative)
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.
Satisfying batteries (Score:4, Funny)
My wife seems to be "satisfied" by energizers while I'm away...
The Great Battery Shootout (Score:5, Informative)
Battery FAQ (Score:5, Informative)
BATTERY BRAND SHOOTOUT (Score:5, Informative)
A few tips (Score:5, Informative)
- 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!Re:A few tips (Score:3, Informative)
Battery Tests (Score:4, Informative)
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.
Just researched this... (Score:5, Informative)
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.
Re:Just researched this... (Score:3, Interesting)
One thing about NiMH, they need to go through about 3 dicharge/charge cycles before they come up to full capacity.
The place where I bought mine says to keep your batteries in a sealed bag in the freezer [greenbatteries.com] when not in use, they self-discharge about 40% in about 30 days [greenbatteries.com] at room temperature.
Depends on the application (Score:4, Informative)
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.
Rechargeable AA are getting really good (Score:3, Informative)
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.
Charge cycles and self-discharge (Score:5, Informative)
(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.
NiMH batteries (Score:5, Informative)
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!
Energizer (Score:3, Informative)
avoid "simple" chargers, good ones are cheap (Score:4, Interesting)
Also, when buying NiMH batteries, pay attention to the mAh rating, which is how much power they hold. AA NIMH batteries might range from 1200mAh or lower to 1950 mAh (the best capacity I've bought so far). This gives you a good indication of how long the batteries will last between charge; clearly there is a big difference out there. And the more expensive batteries do not always have the greatest capacity.
On chargers, there are a lot of different and bad chargers out there. The worst never shut off, just tell you to be sure you only charge batteries for x hours. If you forget and overcharge you can destroy the batteries! Also, if the batteries were not completely discharged then you can overcharge and destroy the battery even if you charge for only the time stated.
The next worst chargers have a simple timer in them and do shut off after x hours. But they still can overcharge a battery if it wasn't fully discharged, or if you try to charge a lower capacity battery. And if you get a higher capacity battery and try to charge it, it will not fully charge.
My rule of thumb is that I never use a charger that insists on charging batteries in pairs. Such chargers cannot sense individual cells, which would allow them to stop charging each cell when it is fully charged. There are a few chargers out there that do sense individual cells and shut off properly though. I think Best Buys sells one for about $30. However, the $9.99 Ray-O-Vac NiMH charger sold at WalMart does this fine. I'm not a Ray-O-Vac fan at all, but I do use and recommend this charger.
And take batteries out of any charger when charged, never trust chargers that promise to keep batteries ready by trickel charging them. I've had them cook batteries.
Again, I want to stress that one should never use chargers that do not sense individual cells and that have to charge in pairs. I have several (I just got one with the 1950 mAh batteries I bought recently) but never use them (I bought the batteries and recharger just to get the batteries, the price was right). Don't risk your expensive batteries to a cheap charger, it will seem to work fine for a while, then you will find that all of you batteries have started leaking and failing.
Remember to look for and pay attention to that mAh rateing when buying batteries.
In applications where the battery might last for years (TV remote control for example, or garage door opener) do not use rechargable batteries. Use Alkaline batteries in these applications; rechargeables will loose their charge too fast, and alkalines are the best choice (I have a garage door opener with the same alkaline battery in it for 19 yeras now).
And thanks for asking here rather than doing a simple Google search on the topic.
Different battery options (Score:4, Informative)
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.
Battery choice depends on environment. (Score:5, Informative)
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.
More on "memory" (Score:4, Informative)
Panasonic makes most of the cells any way (Score:4, Informative)
Rechargeable alkaline (Score:4, Informative)
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.
Alkaline rechargeable (Score:5, Informative)
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.
Re:Rechargable Alcalines (Score:5, Informative)
-Matt
Re:I like lithium beter than NiCad (Score:4, Interesting)
It's important to differentiate between batteries and cells when talking about deep discharge, too. An individual cell can be taken down to 0v without major damage. Once in a while it can be beneficial, to reform the electrolyte. However, in a battery pack, which has several cells wired in parallel, discharging until "flat" can cause serious damage: The cells in the pack are not identical, some of them hold slightly more charge than others. As the pack voltage drops, some of the individual cells near zero, cross it, and actually get reverse charged by the other cells in the pack. Reverse polarity destroys cells very effectively. Packs should never, never, ever be discharged below 0.5v per cell.
As to the parent post: Lithium-ion chemsitry produces 3.6 volts per cell, which is fine if you're designing a new device, but it makes them unsuitable for retrofit or use in standard AA applications. Lithium secondary cells are also tremendously sensitive to current and voltage limits during charging. Exceeding their specifications can cause pressure buildup, violent cell rupture, damage to the device and possible injury to the user. Because of liability, manufacturers don't sell bare lithium secondary cells to Joe Hobbyist. You can buy packs, with the appropriate overcharge protection circuit already wired in series.
Lithium primary (non-rechargeable) cells, on the other hand, are very handy in certain consumer applications: They produce 3.0 volts per cell, exactly double that of the traditional carbon-zinc and alkaline chemistries. They're also very light. The CR-V3 battery is designed to drop into compartments that would normally hold a pair of AA's. Certain digital cameras are designed with the CR-V3 in mind, giving the user a lot of flexibility in battery selection: My Olympus C-2100 can take four AA's of any chemistry (although alkalines don't last very long), or a pair of CR-V3's if I want to travel light and don't mind the price premium.
Since 9 volts is an even multiple of the Lithium primary cell's 3-volt output, lithium-based 9-volt batteries are now available for applications like smoke detectors. They're also ideal in certain LED flashlights, where the low discharge current is well-suited to the lithium chemistry, and the light weight means that many such flashlights will float, which they wouldn't do if heavier alkaline batteries were used. However, none of this is relevant to rechargeable applications.