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Power Science

Memory Effect Discovered In Lithium-Ion Batteries 157

Posted by samzenpus
from the a-little-less dept.
rwise2112 writes "Lithium-ion batteries have long been thought to be free of the memory effects of other rechargeable batteries. However, this appears to be not the case. Scientists at the Paul Scherrer Institute PSI, together with colleagues from the Toyota Research Laboratories in Japan have now discovered that a widely-used type of lithium-ion battery has a memory effect."
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Memory Effect Discovered In Lithium-Ion Batteries

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  • paywall derp (Score:5, Informative)

    by SpaceManFlip (2720507) on Monday April 15, 2013 @01:46PM (#43453705)
    shit's paywalled man, no good for Freedom Internets
  • No Shit (Score:2, Insightful)

    by Anonymous Coward

    This has actually been theorized for a long time by people that use Li-On batteries and have to charge them frequently. But they've been told 'nope impossible' by the people who make and research Li-On batteries the whole time. To me this is just like the pharmaceutical industry pushing the next opiate as 'non habit forming' and 'extremely safe' only to have it turn out even more addictive and deadly than the last iteration...time after time.

    • Re:No Shit (Score:5, Informative)

      by thaylin (555395) on Monday April 15, 2013 @02:54PM (#43454401)
      Well from the article it is possible to cause it to "forget" the memory so it is understandable why some people see it and others dont see it at the same time.
    • Re:No Shit (Score:5, Interesting)

      by BitZtream (692029) on Monday April 15, 2013 @05:35PM (#43456143)

      No one with any actual understanding of batteries said Li-Ion does not have memory.

      What was said is that: From a practical perspective, Li-Ion memory is not an issue to worry about.

      The article is basically someone who just did a study to confirm what probably every battery manufacture on the planet knew about Li-Ion at least 15 years ago. Longer I'm sure, I just have no experience before that.

      What they did was took something they interpreted incorrectly, and then did a bunch of research to disprove some statement they misheard.

      This is roughly like me telling you the surface of the earth is flat when you're building a small house, and then having a bunch of morons who overheard our conversion from 3 tables over do a study to determine that no, infact the Earth isn't flat. Of course its not flat, but from a practical perspective to the man building his home, its flat.

    • Re:No Shit (Score:5, Interesting)

      by Tobia Conforto (2818827) on Monday April 15, 2013 @05:45PM (#43456225)

      Yes shit. People who "use Li-On[sic] batteries and have to charge them frequently" are simply incurring in an unfortunate characteristic of Li-ion batteries, namely that they have a finite number of recharge cycles, or equivalently, that each recharge cycle diminishes the total charge the battery can hold.*

      This has nothing to do with a memory effect.

      For comparison, Ni-Cd batteries (as seen for example on power tools) have a strong memory effect, meaning that if you plug them in before they are exhausted, they "remember" the smaller capacity you've used them for, and it takes a number of complete discharge and recharge cycles to restore their full capacity. Of course, all that's needed to fully utilize Ni-Cd is a slightly more expensive charging circuit that fully discharges the battery before switching to recharging, which is why they are widely used in professional applications.

      _____________
      * Battery-savvy users always keep their mains plugged in on Li-ion devices such as laptops, so that the battery undergoes few recharge cycles and still performs as if it were new when they need it to, even after years of usage. But not after too many years, because Li-ion also have a limited timespan, or equivalently, the total charge they can hold diminishes every second since they leave the factory. Yes, it's a complex world.

      • Li-ion batteries suck. Their lifespans are considerably reduced if they are either fully charged or fully discharged; ideally they should be kept in the 40%-60% range. Since no charger does that, they are pretty much doomed. Expect your laptop battery to be effectively useless within 3 years of purchase, particularly if it's kept plugged in at all times.
        • by swalve (1980968)
          If you know it, then the engineers who design battery charging systems in complex devices probably know it too.
        • by russotto (537200)

          Li-ion batteries suck. Their lifespans are considerably reduced if they are either fully charged or fully discharged; ideally they should be kept in the 40%-60% range. Since no charger does that, they are pretty much doomed.

          They have their problems, but for charge efficiency and energy density, they're way ahead of the rest. They also don't self-discharge to any great extent. They're doing well on power density now too.

          Your alternatives are a memory-laden NiMH battery which wastes 30% of its charge and ha

        • by green1 (322787)

          Li-ion batteries suck. But they suck ever so slightly less than NiMh batteries, which suck ever so slightly less than NiCd batteries... which makes Li-ion the best of the common technologies available right now.

          Battery technology has been improving constantly. That said, it is nowhere near what people want it to be for our increasingly battery dependant lifestyles.

        • Expect your laptop battery to be effectively useless within 3 years of purchase, particularly if it's kept plugged in at all times.

          IBM/Lenovo Thinkpads offer a way in their battery gauge / power management software to prevent recharging until the battery falls below X%. I usually set my users at 85% or 90% as the threshold before charging begins. At which point, it charges from X% up to 100%.

          Usually only happens about once every 1-4 weeks, depending on how much they leave it hooked up to the wall out
  • by geoskd (321194) on Monday April 15, 2013 @01:52PM (#43453753)

    The question is: how big is the effect. Even a small effect will cause significant distortions in battery metering, but if the effect is large enough, it will cause the batteries not to last any where near as many cycles as originally believed. This could really suck for electric car owners. Any '07 Roadster owners out there care to share how well the batteries are holding up?

    -=Geoskd

    • by jeffmeden (135043) on Monday April 15, 2013 @01:58PM (#43453821) Homepage Journal

      The question is: how big is the effect. Even a small effect will cause significant distortions in battery metering, but if the effect is large enough, it will cause the batteries not to last any where near as many cycles as originally believed. This could really suck for electric car owners. Any '07 Roadster owners out there care to share how well the batteries are holding up?

      -=Geoskd

      According to what I could read of TFA without paying $32, the memory effect is actually seen just during discharge, as a function of distorting the voltage vs w/hr capacity. The overall w/hr capacity of the battery is not reduced, but the ability to exactly determine SOC is diminished at mid voltage levels.

      I am not a chemist, so input from someone with more insight on the exact study would be appreciated.

      • by Anonymous Coward on Monday April 15, 2013 @02:35PM (#43454195)

        Pretty accurate. They see a small deflection on what was commonly believed to be a smooth curve near the previous peak charge.voltage. It does not affect the overall charge capacity of the battery over time (what people commonly think about when "memory effect" is used), just the ability of the charge/lifetime remaining software to make accurate estimates.

        For all examples shown, a user would be told they have significantly more charge remaining until near that point, then immediately after it would appear their predicted battery life would drop dramatically, and then it would stabilize again. It makes sense that this would be of keen interest to Toyota and other electric vehicle manufacturers.

        If their graphs are as accurate, noise-free and reproducible as the figures lead the reader to believe... then the good news is, this effect can probably be accurately modeled and compensated for now that we know it exists. In that respect, it is a significant step forward for Li charge remaining prediction software.

        • I wonder if that's why my G3 ibook battery shit the bed 2 days before I went on vacation that one time. I still got around 4 hours of runtime out of it (I'd checked a couple weeks earlier to be sure I didn't need a new battery) but the charging system suddenly refused to charge it. Of course, it was so old by then that I couldn't even pay full retail for one at the Apple store because they'd stopped stocking them a year or two earlier. I had to suffer without a battery through my vacation and ordered a r

          • My 13" MacBook (late 2008 unibody model) had to have its battery replaced once. At first I started to notice that the battery cover wouldn't close all the way flush. Over a period of a few months, I could only get 30 minute of life out of it on a full 100% charge. A few battery utilities said I had 100% life left in it. Obviously something didn't add up. So I swapped the battery and all was well.

            As for the old battery pack, it had a slight bulging to it. It would rock back and forth a little when placed fla

            • by swalve (1980968) on Monday April 15, 2013 @09:34PM (#43457685)
              The only way to know the state of charge is by measuring voltage. Sometimes, batteries fail in that they never manage to get to their "charged up" voltage. Other times, they fail where they appear to top off instantly, and since the voltage is correct, the battery utilities think it is charged. The only way to actually test a battery is to put a known load on it and see how long it takes to hit a certain voltage.

              What you experienced was not memory effect, but one or more of the cells failing. Some of them probably would never charge completely up, and the other cells got pushed into over voltage to compensate. If you have cells in series, this is pretty much going to happen sometimes.
      • by tibit (1762298) on Monday April 15, 2013 @02:37PM (#43454217)

        Voltage monitoring should be just one aspect of charge determination. Properly done charge monitoring integrates the electrical charge actually delivered to or taken out of the battery -- as in taking the time integral of the current. The cell voltage should only used together with other indicators (cell temperature!) to determine each cell's health and charge/discharge endpoints (fully charged and fully discharged). The cell voltage should not figure in normal battery "% remaining" indications -- those solely base on the charge taken out of the battery, and the estimation of the 100% charge capacity.

        • by swalve (1980968)
          It turns out that voltage is a pretty good indicator of all that fancy monitoring, making it largely unnecessary. Especially since all that monitoring will use up the power the battery is trying to maintain. And it solves no problems in most devices- a bad battery is a bad battery, doesn't really matter how it went bad.
          • by tibit (1762298)

            It does matter because if you properly monitor it, you can not only prevent it from going bad by equalizing the charge on all the cells, but you can also bypass the bad cells. Every modern automotive battery stack has such monitoring and cell bypass. Your electric vehicle will work perfectly fine with a bunch of dead cells. Besides, all this "fancy monitoring" for mobile device battery packs fits in one chip. There are multiple vendors and the market is quite competitive. There is a good reason that charge

    • According to the first link the issue can be fixed with a software change, and can also be worked around by a full discharge followed by letting the system rest. Doesn't say how long a rest is needed though, depends on the implementation I suspect.

    • by Anonymous Coward on Monday April 15, 2013 @02:44PM (#43454289)

      The question is: how big is the effect. Even a small effect will cause significant distortions in battery metering,

      True, and this is what is seen.

      but if the effect is large enough, it will cause the batteries not to last any where near as many cycles as originally believed.

      Rubbish. It doesn't diminish the battery's capacity, just changes the q-v characteristic DURING CHARGING. Even if it were a large effect, it's still not going to effect total capacity, or estimating remaining charge by measuring voltage during discharge.

      Notes regarding this:
      1. This effect is shown in LiFePO4, which is commonly marketed as a "safe" chemistry Li-ion. Laptop and mobile phone batteries almost universally use LiCoO, which is not, AFAIK, addressed in this research. The Tesla Roadster also uses either LiCoO or LiMnO (I've seen conflicting reports -- probably because these two have similar electrical characteristics -- and both have much better energy density than LiFePO4), so your plea to Roadster owners seems a little odd...
      2. This effect is caused by starting with discharged battery, charging partially (greatest effect for charging ~50%), discharging completely, then recharging completely. During the final (complete) charge process, the voltage starts at baseline (i.e. full-discharge/full-charge cycle, at the same % charging), increases slightly faster than baseline, so that the voltage difference over baseline peaks at 50% (or whatever state you partially charged it to), then increases more slowly than baseline to arrive at the same voltage when fully charged -- so capacity measured while charging will be overestimated. On the subsequent discharge, however, the q-v characteristic conforms to the baseline -- so capacity remaining will be measured accurately when a device is in use.

    • The real question is: is the effect real? NiCd and NiMH batteries don't actually have a memory effect; that's not a real thing, it's just folklore.

      NiCd batteries, for example, experience a memory effect if discharged to the same exact level +/- 3% repeatedly MANY times, where the output voltage is not below roughly 1.0V, and the maximum charge is below or exactly 100%. If the batteries are charged with full overcharge or the level of discharge between charges varies by more than 3% or goes below 1.0V, m

    • by wildsurf (535389) on Monday April 15, 2013 @04:26PM (#43455405) Homepage

      Any '07 Roadster owners out there care to share how well the batteries are holding up?

      My '08 Roadster (there are no '07 roadsters) has 33k miles on it, and after 4 1/2 years, its battery capacity has been reduced about 8%. I now get 225 miles on a full charge, down from 244 on day 1. That's even better than Tesla's initial projections, actually.

      • by BitZtream (692029)

        Thats because you aren't driving it. You're basically treating the batteries in the ideal way judging by time and milage. You'd probably get slightly worse than that if you didn't drive it at all.

    • And besides that, if you look at the charts, this doesn't cause a loss of capacity, even an apparent loss of capacity. Instead the voltage just reads high during charging. It appears it can foul up capacity remaining estimates, but not actually change the capacity remaining.

    • Tesla does not use that chemistry. Nissan and the others DO. From talking to Tesla ppl, the batteries are holding up great.
  • In the source article, I notice it's only about a 4 percent total effect on total charge.

    So, while not "no memory effect" it's not as bad as the impacts on the other types of battery storage.

    Even storage devices like compressed air (PHES) for wind and solar PV systems have only a 70 percent efficiency, so it's still way better than that.

  • by DigitAl56K (805623) on Monday April 15, 2013 @01:56PM (#43453801)

    LiFePO4.

    Cliffhangers in the summary now?

    • by afidel (530433) on Monday April 15, 2013 @02:01PM (#43453845)

      And I wouldn't call LiFePO4 "widely used", it's hardly used at all in the west due to extremely high royalty rates charged by the patent holders. I'd actually love to use LiFePO4 cells for my camping solar setup but the only ones I can find are dodgy Chinese imports with questionable charge controllers.

      • I'd actually love to use LiFePO4 cells for my camping solar setup but the only ones I can find are dodgy Chinese imports with questionable charge controllers.

        I can't really vouch for their quality because I am far from a battery expert, but Ping Battery [pingbattery.com] is very highly respected among DIY electric bicycling enthusiasts.

        Definitely place them in your category of "dodgy Chinese imports", but anyway they're considered to be very reliable among that particular category!

      • LiFePO4 batteries are starting to be used in motorcycles. I have a Shorai branded one in one of my bikes. Compared to a conventional lead-acid battery, it is smaller and much lighter. It also has a very limited self-discharge rate which means I don't have to charge the battery when the bike is stored during winter. I do disconnect and bring inside the battery due to the cold weather and parasitic draws.

        The downsides that I knew about are that they don't work as well in colder weather and they're not com

      • by Rich0 (548339)

        I'd actually love to use LiFePO4 cells for my camping solar setup but the only ones I can find are dodgy Chinese imports with questionable charge controllers.

        Hey, they could come in handy if you ever run out of tinder and kindling!

        • by afidel (530433)

          I've used the 9V and pot scrubber trick to start a fire when both my lighters failed on a camping trip (I wasn't going far enough away from society to pack the parafin encased bluetips which are my backups when my life depends on fire).

    • Re: (Score:2, Interesting)

      by GameboyRMH (1153867)

      Which is actually a very uncommon form of li-ion battery. Military drones use it, the batteries are taken out of service after just a few charge cycles.

    • by hey! (33014)

      Thanks for spoiling the story for me. Now I guess I'll have to read something else.

  • Wrong description (Score:5, Informative)

    by folderol (1965326) on Monday April 15, 2013 @01:58PM (#43453815) Homepage
    I do wish people would stop calling it a 'memory effect'. It's probably the least descriptive term your could apply.

    I don't know about Lithium batteries but NiCad cells exhibit a second plateau which gradually gets more difficult for the charge system to punch through. The usual cure is a couple of heavy charge/discharge cycles.

    Don't think I want to try that with Lithium though!
    • by thaylin (555395)
      Actually it is very descriptive. It remembers the last charge cycle and begins to memmic it which is different from the system just plateauing.
  • by toygeek (473120) on Monday April 15, 2013 @02:00PM (#43453831) Homepage Journal

    I've always wondered why they say that Lithium Ion and Lithium Polymer batteries don't have a memory effect, when even laptop batteries based on those technologies die after several years, and NOT because of charge cycles. I'm talking about the ones that stay plugged in most of their lives, charging. Maybe its the lack of charge cycles that kills them? But to say Lithium batteries have no memory effect has always been ludicrous to me.

    • by Anonymous Coward

      Batteries should be stored in a cool location. Keeping a battery in your notebook for long periods of time when running off of AC subject it to high temperatures and a shortened lifespan.

      • Re: (Score:2, Interesting)

        by Anonymous Coward

        "
        Batteries should be stored in a cool location. Keeping a battery in your notebook for long periods of time when running off of AC subject it to high temperatures and a shortened lifespan.
        "
        Nope, that's not the reason.

        Typically, a new laptop owner does the following.
        Buy new laptop
        Install battery (if it's not already)
        Place on desk.
        Plug in to AC power.
        Use for 5 years or less, and never move it from that spot.

        In other words, the battery is NEVER used.
        I've seen it personally with the last 3 business laptops I've

        • by Anonymous Coward

          I've seen it personally with the last 3 business laptops I've had (hp, lenovo, dell) as well as the past four personal laptops i've sold to people. Those that actually use the battery down to zero at least once a month? Batteries last forever.

          That's true for older technologies, but not true for lithium-ion. They will lose capacity no matter what you do. They'll lose it faster when fully charged and at higher temperatures, but they'll always lose capacity.

        • by mikael (484)

          The battery is used. If there's a power blackout, the laptop keeps on going. The desktop, DVD player, cable box, satellite box, and plasma TV have all gone out and go back into their respective boot-up sequences.

        • by Immerman (2627577)

          What? AC is completely correct, and you failed to even address their comment in any meaningful way, except that, yes, I too have noticed occasional deep cycling seems to help preserve battery capacity.

          Heat deteriorates li-ion batteries - and being in a laptop with a cpu, HD, etc all running at max because they're on AC subjects them to lots of heat.

          Being held at 100% charge also wears out li-ion batteries, there's a reason that a Prius strives to keep it's batteries between 40 and 60% charged most of the t

        • by Osgeld (1900440)

          I remember such software

          it nailed your hard disk for 3 hours causing that to fail

    • by Maximum Prophet (716608) on Monday April 15, 2013 @02:12PM (#43453943)
      With any battery technology, it's almost never the "Memory Effect", but simple overcharging. If your laptop batteries are always hot just sitting there when the laptop is plugged into the mains, they won't last as long as ones that are properly charged and left alone until they are needed for discharge. With cheap cordless drills and other tools, simple putting a timer on the charger will greatly increase the number of cycles you can get out of the batteries.
      • by sunking2 (521698)
        The overall Works Like Crap Effect is still the same for the consumer. Semantics of the cause doesn't make the user any better off.
        • by Anonymous Coward

          I'll put it simply the designers are too cheap to simply put a timer circuit/code in place to stop charging the damn battery because it's already as charged as it's going to be....

      • High battery temperature and a high state of charge is a killer combination for Li-ion batteries. This is exactly what happens in a laptop that is plugged in and running. An electric car, on the other hand, usually avoids this. My Nissan Leaf charges to 80 % SOC, unless I explicitly ask it for a full charge, and even then it will not allow the batteries to reach the real 100% SOC. (Just like the batteries aren't really empty at 0 % SOC.) The advice is not to leave the batteries at full charge for more than
      • by tibit (1762298)

        With modern charge controllers, there is no overcharging of any sort -- a charged battery pack is not being charged anymore, that's it. Only after it self-discharges a bit -- enough so that it's detectable -- will it be topped up. The problem you have of course is that the battery pack is still treated as a whole and while charge controllers in mobile device battery packs will detect voltage on individual cells, still very few have the electronic bypass switches needed for cell charge equalization and cell

    • by Ecuador (740021)

      I don't see how plugged-in laptop batteries dieing has anything to do with a memory effect. Lithium-Ion batteries when stored lose capacity depending on how much they are charged and how high the temperature is. At the relatively high temperatures of a laptop and kept at near 100% charge they can lose as much as 40% capacity per year. This is a known fact and has nothing to do with what is called memory-effect. The summary talks about a specific (and not widely used as I understand it) kind of Lithium batte

    • by Firethorn (177587) on Monday April 15, 2013 @02:32PM (#43454159) Homepage Journal

      Okay, first up let's define memory effect: Memory effect is NOT a battery dying. Memory effect is the tendency for a battery to stop charging/discharging at a set level if you regularly fail to completely charge/discharge it. It develops a 'memory', and thus falsely acts as though it's fully charged or discharged before it actually is.

      While this can ruin a battery, a number of techniques have been developed to rehabilitate such batteries to restore full function.

      However, batteries don't just wear from charge/discharge cycles. They age over time as well. Alkaline and Lithium primary cells are especially resistant to this, but until very recently LiIon rechargeable cells were very, very vulnerable to this, losing 10% or more of total capacity just sitting on a shelf in a cool warehouse at 70% charge(the ideal situation for them).

      Sitting in a hot laptop being kept at 100% is much worse than ideal, you could be losing 30% or more per year in that scenario.

      • by mybecq (131456)

        being kept at 100% is much worse than ideal

        This is at the heart of my laptop battery experience. My laptop is rarely off AC power. When I had the charger set to stop charging at 100% (and to recharge when 90%), my battery life greatly improved. OId battery dropped 60% in reported capacity in less than 2 yrs; new battery is barely down 30% in the following 4 years.

        I call it Chinese electron torture for your battery -- drip, drip, drip.

        • by Firethorn (177587)

          The new battery might be using the improved technology as well, but you'd probably save even more life if you can set the charger to recharge at 60% and stop at 80%.

          After that it's a fight against heat. Keep the battery under 70F and you'll slow it's degradation even more.

          Then again, 30% in 4 years might be slow enough for your purposes.

    • by tibit (1762298)

      The problem with most batteries is that the designs are cheap and the cells are not individually controlled with bypass switches. Then you have a pack with just one bad cell and the whole pack is "bad". All the rechargeable battery pack failures I've seen were of this kind: one weak cell with all the others having lots of life in them. The bad cell issue is self-exacerbating: as soon as a cell has higher internal resistance than the others, it will always get overcharged and over-discharged, accelerating t

      • Holy shit someone is wrong on the Internet.

        Each cell supplies a certain amount of voltage. Lead-acid, carbon-zinc, and alkaline batteries supply 1.5V per cell. Remove a cell and the voltage potential drops, which plays hell with electronics not ready for that big of a fluctuation. For example, when a car battery loses a single cell, it usually can't start the engine--it definitely can't when it's cold. Sensitive electronics may have some very odd issues with different input voltages. It's possible to

        • by tibit (1762298)

          Remove a cell and the voltage potential drops, which plays hell with electronics not ready for that big of a fluctuation.

          I don't know what kind of electronics don't use flexible switching power supplies these days, but yeah, if the latest you've seen is stuff from the 80s, then you might have had a point. These days a laptop power supply might use a battery with a total voltage anywhere between 12 and 30V, but all the heavy power consumers besides screen backlight and hard drive actually run on a couple of Volts. The power supplies for many of today's electronics wouldn't even notice if a cell drops out -- everything will ke

    • by jittles (1613415)

      I've always wondered why they say that Lithium Ion and Lithium Polymer batteries don't have a memory effect, when even laptop batteries based on those technologies die after several years, and NOT because of charge cycles. I'm talking about the ones that stay plugged in most of their lives, charging. Maybe its the lack of charge cycles that kills them? But to say Lithium batteries have no memory effect has always been ludicrous to me.

      Actually overcharging your Li-Ions and Li-Pos is bad news. It shortens the life of your battery. You can't trickle charge them, so as you use the device plugged in, the battery discharges to some threshold, where the battery controller starts charging it again. So even if you leave it plugged in 24x7, if the battery is plugged in, it will discharge and then recharge at some frequency.

    • Leaving a lithium battery plugged in all the time while in use is actually the best way to damage it and shorten its life span :)
  • and I wish you didn't have to hack your way in to replace them.

  • It pays to charge your batteries based on your instinct and tradition "just in case" instead of just believing and falling for claims that are only to be proven false later...

    Well, I'm set, because I always let my phone nearly die before charging it. That's sure as hell not gonna change now.

    • by ledow (319597)

      Nice. Because that's the worst thing to do to a Lithium-ion, for example.

      • by tibit (1762298)

        I have a Makita LXT drill and screwdriver and I've been beating the crap out of them, running the batteries down each time until the performance drops low enough to make me have to switch. No problems so far, even though I've had them 3 years or so. I'm drooling for the new brushless versions, but seriously I have no reason at all to replace what I have -- they work great in spite of using brushed DC motors.

      • by Immerman (2627577)

        Are you sure? I thought it was letting them *totally* die that was a problem. I've noticed deep-cycling them (to 10%) occasionally, maybe once every month or two, seems to do them good, not that I've done any rigorous testing, just noticing how changing behavior patterns seem to affect them.

        Of course the biggest benefit was when I disabled "maximum performance mode" when connected to AC. Battery-saver mode gives me plenty of performance 99% of the time, and the lack of lap-roasting heat and a roaring fan

      • Nice. Because that's the worst thing to do to a Lithium-ion, for example.

        You tell that to my phone, which after a full year and a half is still capable of running as long as it could when I bought it. Actually, it was lasting a day or less when I first bought it (largely due to a battery-guzzling bug that I found out how to solve), but now a whopping seven days. Lots of tweaks to reduce power draining too, but it's still running the same stock OS on the same battery it came with.

        By comparison, many of my friends leave their laptops and cell phones plugged in 100% of the time t

      • The worst thing you can do to a lithium ion battery is to leave it fully charged. That's the quickest way to wear it out. (aside from the obvious over charging and over discharging)

      • The worst thing to do with a Li+ battery is to keep it fully charged.
  • I need science to figure out why my significant other has these 'memory issues' -- I'd like to win at least one discussion in my life...
  • by WaffleMonster (969671) on Monday April 15, 2013 @03:51PM (#43454943)

    First of all of LiFePO4 are not commonly used in any of our portable gadgets.

    Second memory effects we are seeing in our gear are illusions based on memory effects in the electronics that help figure out capacity. Deep cycling lion batteries works to clear these effects as what you are actually doing is resetting the "gas gauge" to synchronize with reality of the battery.

    • by BitZtream (692029)

      First of all of LiFePO4 are not commonly used in any of our portable gadgets.

      Lithium Ion != Lithium Iron ... i.e. WTF are you bringing up LiFe for? Not part of this conversation.

      Second memory effects we are seeing in our gear are illusions based on memory effects in the electronics that help figure out capacity. Deep cycling lion batteries works to clear these effects as what you are actually doing is resetting the "gas gauge" to synchronize with reality of the battery.

      Actually, you have that backwards.

      The batteries have degradation. The electronics are wrong because they remember capacity based on the charge/discharge cycle of the battery when it was new. Over time it degrades, this is not memory, its just degradation ... wear. When you 'deep cycle' the battery, all you are doing is allowing the device to actually see how the battery is currently performing rather tha

      • Lithium Ion != Lithium Iron ... i.e. WTF are you bringing up LiFe for? Not part of this conversation

        Please RTFA.

        Actually, you have that backwards.

        The reverse of what I said would be memory effects in batteries which is not occuring.

        The batteries have degradation. The electronics are wrong because they remember capacity based on the charge/discharge cycle of the battery when it was new. Over time it degrades, this is not memory, its just degradation ... wear.

        Normally it is a simple loss of synchronization rather than meaningful change to capacity. The most common issue stems from self discharge not being accounted for over prolonged periods of nonuse.

        When you 'deep cycle' the battery, all you are doing is allowing the device to actually see how the battery is currently performing

        Thanks for agreeing with me.

        rather than how it was expected to perform a hundred charges ago.

        It is more complicated than this.

  • Tell me when there is a problem with cobalt lithium batteries.

  • by BitZtream (692029) on Monday April 15, 2013 @04:55PM (#43455727)

    And I expect never will. All batteries have various flavors of memory. The only question is, does the memory effect cause enough of a problem to make it worth addressing the issue to extend battery life.

    You worry about memory in a NiCad because the process that causes the memory is easily reversible (partially), and the battery itself is still functional.

    If the memory effect of Li-Ion only effects ... say 1% of the total capacity before the rest of the chemical processes break down and cause the battery to 'wear out' than it has memory, but from a practical perspective the memory is irrelevant.

    There are all sorts of batteries that would appear 'memory less' at first glance, but thats only cause they are so shitty in other ways that you don't get to the point of noticing the processes that cause memory to start happening.

    Until a battery is 100% energy efficient, its going to have memory, so never.

    • by spongman (182339)

      modern NiCad don't exhibit the memory effect. there are other effects such as depression and aging, but not memory.

  • People who keep their laptops on AC are NOT killing their batteries by keeping the system on AC. The batteries are being killed by the fucking design of the laptop's charging circuit! Bonehead charging systems will keep trickle charging the battery even when they shouldn't! The end result is shortened battery life. In effect the laptop was designed to kill the battery prematurely.

    Properly designed charging systems do not do this. If you bought a cheap-ass laptop you can expect it to chew up batteries

Reality must take precedence over public relations, for Mother Nature cannot be fooled. -- R.P. Feynman

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