Memory Effect Discovered In Lithium-Ion Batteries

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."

Comments

paywall derp

[SpaceManFlip]

shit's paywalled man, no good for Freedom Internets

Re:paywall derp

[Vanderhoth]

It's ok, No one here needs to read the article anyway. I kid of course ;)

No Shit

[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

[kelemvor4]

Man ... living in your head must be terrible, in a world so full of daemons and enemies constantly conspiring against you. No wonder you are a bitter AC.

To my knowledge, both his assertions are accurate. One of them is supported by TFA.

Re:No Shit

[thaylin]

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

[Anonymous Coward]

His other assertion is in regards to heroin in that it was suppose to be less addictive than morphine.

In case anybody was wondering.

Re:No Shit

[Anonymous Coward]

or Oxycontin or dilaluid or...

Re:No Shit

[BitZtream]

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

[Anonymous Coward]

...The cure to opiate addiction Suboxone (buprinorphine) has recently shown to be much more addictive and difficult to discontinue than many of the original opiates patients were on to begin with. FDA intervention required the manufacturer late last month to release its patent to two other companies so they may begin producing to keep up with the sudden onslaught of demand. For a drug meant to get people off drugs. Substituting one for another and making quite the profit as average cost is 250 USD for 30.

Just something I've come across in my work and a growing concern among my coworkers.

Re:No Shit

[tobia.conforto]

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.

Re:No Shit

[ChrisMaple]

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.

Re:No Shit

[swalve]

If you know it, then the engineers who design battery charging systems in complex devices probably know it too.

Re:No Shit

[russotto]

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 has lousy power and energy density, not to mention a ridiculously high self-discharge rate (except LSD cells which have worse energy density). Or a NiCd which is about the same as NiMH except with better power density and more toxic waste. Let's not even get into lead-acid.

Yes, Li-Ion cells suck, But they're the best we've got.

Re:No Shit

[green1]

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.

Re:No Shit

[WuphonsReach]

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 outlet vs carrying it around.

Other brands might offer similar features, but we only use Thinkpads.

Re:No Shit

[Anonymous Coward]

I already forgot what you wanted me to remember...

Re:No Shit

[Anonymous Coward]

Even that's not true. Most Ni-Cd cells exhibit little to no memory effect, and those that do only show it under very controlled charging conditions. Any charger that overcharges Ni-Cd cells (pretty much all of them) will eliminate the memory effect, even in the few cells where it can occur at all. A full discharge is not required, and can be harmful to multi-cell packs.

Voltage depression is frequently confused with the memory effect. It doesn't change the actual amount of charge stored, only the voltage at which that charge is released. It can be reversed by a full discharge, but with the same risks to multi-cell batteries. It's mostly harmless, and generally just confuses built-in battery meters.

For more details see Dan's Quick Guide to Memory Effect, or Wikipedia if you prefer.

And incidentally (I know you didn't claim this, but it's a relevant point anyway), for Li-ion, a "charge cycle" is measured as a series of charges equalling the full capacity of the cell. It doesn't matter much whether that's one full charge, or five 20% charges. If anything, it'll probably last longer with the 20% ones. Fully discharging your laptop battery won't make it last longer - if anything, it'll kill it faster.

Re:No Shit

[Anonymous Coward]

I know Sony is evil, but I have one of their Vaio i7 laptops which is about three years old and their "Battery Care" feature allows me to choose what percentage charging level (100%, 80% or 50%) I want.

This is a perfect solution to this problem. While I use my laptop as a workstation I set the charge point to 50% and it sits there for a few months on mains power. Then, when I know I am travelling tomorrow I dial it up to 100% and use it that way for a few days while I travel for business. Then once I'm back home I set it back to 50%.

Works very well and this should be a standard feature on all laptops, and indeed, built into the OS.

Re:No Shit

[Anonymous Coward]

...and sadly, they do nothing about it. You think otherwise? Where's the option on your laptop to charge the battery to 50% and just leave it there?

A few years ago I bought a Macbook (apple sucks, don't buy apple), my first-ever laptop. Being able to just unplug it at any time and carry it around was awesome. After a few years, however, the battery began to swell, and so I tossed it, and bought a new one. A year later, the same thing happened, so again I tossed it, but didn't see the point in wasting more money on something that I rarely use. So now that laptop just serves as a desktop.

Considering how rarely I used that battery, it'd been nice if it had an option to charge it only to 50% so that it would last as long as possible. In particular, the thing would last for hours, yet I primarily used it just to power the laptop as I moved around, e.g. keep it running while I carried it out to the car, where I then plugged it in again. So 50% of the battery's capacity would have been wonderful.

I once considered building a switched outlet which my laptop would then turn on when the battery reached 40% charge, then turn off when it reached 60% charge, but considering that constantly charging and discharging isn't the same thing as charging to 50% and then leaving it alone, it didn't seem like a worthwhile thing to do. ...and, indeed, I suspect the reason the battery decided to swell up on both occasions was because somehow Linux wasn't allowing it to charge correctly. After all, I had no problems with it when running MacOS for a few months before realizing it sucked ass, then when running Windows for a year before realizing that Windows was so useless that I never used my laptop at all. It wasn't until after I switched to Linux that I started having issues.

Re:No Shit

[romons]

FWIW, my vaio has a facility to keep the battery charged only at 50%, or 80%. When I am plugged in for a few weeks, I drop it down to 50%.

Electric Cars

[Anonymous Coward]

How will it affect Tesla & other mfgs using li-on as their battery system.

Re:Electric Cars

[viperidaenz]

It won't, because they're not using iron cathodes.

Re:Electric Cars

[WindBourne]

Tesla uses a different chemistry, so this does not impact them. However, it WILL impact most of the others.

According to TFA...

[Anonymous Coward]

Lithium-ion batteries actually have a worse memory effect than Ni-Cad batteries, exhibiting the change after just one partial-discharge/recharge cycle.

Small effect big consequences

[geoskd]

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

Re:Small effect big consequences

[jeffmeden]

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.

Re:Small effect big consequences

[Anonymous Coward]

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.

Re:Small effect big consequences

[tibit]

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.

Re:Small effect big consequences

[Anonymous Coward]

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.

Re:Small effect big consequences

[Anonymous Coward]

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.

Actually, it's seen during charge -- discharge proceeds normally, so determining SOC from voltage during discharge is just fine.

Also, please stop saying w/hr when you mean Wh. If you must use busted units, at least use whr, w*hr, or some such notation -- it's multiplication, not division, so there's no sense putting a / there!

Re:Small effect big consequences

[jtownatpunk.net]

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 replacement from Hong Kong when I got home.

Re:Small effect big consequences

[bluefoxlucid]

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, memory doesn't happen at all in any way. Laboratory conditions. Essentially, a memory effect on a NiCd isn't a real thing; you'll never get there without sensitive metering equipment and very deliberate action.

Re:Small effect big consequences

[wildsurf]

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.

Re:Small effect big consequences

[tbird81]

You could consider not paying the "Mac tax" for inferior hardware and poor support.

Re:Small effect big consequences

[Anonymous Coward]

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

Well, the Roadster came out in '08 not '07. But mine has over 80,000 miles on it now. My range seems around 90% of what it was when it was new.

The Roadster batteries are Lithium-Cobalt, though. The article was about Lithium-Iron-Phosphate (like the Volt).

Re:Small effect big consequences

[BitZtream]

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.

Re:Small effect big consequences

[Anonymous Coward]

I kind of wish that you had provided the NiMH example, because my first thought was, "I bet my camera shuts itself off at about the same voltage every time." Also, wireless game controllers are probably fairly consistent about how low they will go, so I would suggest that the number of batteries which see repeated discharges to the same level is, well, a big number.

Re:Small effect big consequences

[Anonymous Coward]

You could consider not paying the "Mac tax" for inferior hardware and poor support.

Is that how you rationalize not forking over the money for the best hardware and best applications in the computing world? (and a pretty good OS)

(Posting AC because I envisage an army of bitter nerds who rationalize in the same way)

Re:Small effect big consequences

[Anonymous Coward]

Back when I still had a wireless mouse, I used NiCd and NiMH batteries, and both do have memory effects. At first the battery would last weeks but after a while a battery would last less than a day and would need to be replaced. This was using a standard battery charger with built-in discharger. But I guess an optical wireless mouse qualifies as sensitive metering equipment.

Re:Small effect big consequences

[WindBourne]

Tesla does not use that chemistry. Nissan and the others DO. From talking to Tesla ppl, the batteries are holding up great.

Re:Small effect big consequences

[Anonymous Coward]

You should be a stand up comedian.

Re:Small effect big consequences

[drinkypoo]

At first the battery would last weeks but after a while a battery would last less than a day and would need to be replaced.

You have completely failed to demonstrate memory effect. All you've shown is that your batteries degraded over time.

Re:Small effect big consequences

[DigiShaman]

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 flat on the table. That's a physical problem beyond a simple memory effect.

Re:Small effect big consequences

[swalve]

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.

Re:Small effect big consequences

[swalve]

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.

Re:Small effect big consequences

[Anonymous Coward]

Get rid of guilty-until-proven-innocent legislature for carrying cash. http://wh.gov/Lu1w

Like you, I think we should oust Congress—and I'm comfortable reversing the presumption of innocence for them.

Haha, yes, though you meant to say "legislation" instead.

Civil asset forfeiture is a travesty and no one can with a straight face argue it is constitutional. You might also consider adding a link to fear.org.

Re:Small effect big consequences

[tibit]

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 integration is the way to monitor battery state of charge -- it's the only thing that really works.

Re:Small effect big consequences

[Anonymous Coward]

Nice way to go off topic.

Re:Small effect big consequences

[darkredhorse]

I have a smartphone....I have known about the memory effect/degradation of life that suddenly increases with excessive discharge for a long time. Not news.

Graphs in linked article show minor effect

[WillAffleckUW]

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.

And that type of battery is....

[DigitAl56K]

LiFePO4.

Cliffhangers in the summary now?

Re:And that type of battery is....

[afidel]

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.

Re:And that type of battery is....

[GameboyRMH]

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.

Re:And that type of battery is....

[UberChuckie]

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 compatible with all battery chargers. Battery chargers with a de-sulphate mode cannot be used.

I wonder what the impact of this discovery is on motorcycle uses. The battery is really only discharged when the starter is engaged. The rest of the time, the alternator is keeping the battery charged and whatever parasitic draws when the bike is parked is minimal.

Re:And that type of battery is....

[Rich0]

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!

Re:And that type of battery is....

[afidel]

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:And that type of battery is....

[hey!]

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

Re:And that type of battery is....

[Anonymous Coward]

they're starting to appear in the remote control car hobby scene, so if you're looking for a source of lifepo4 batteries and chargers supplied by "reputable" brands, that market and the brands servicing it are probably a decent starting point.

Re: And that type of battery is....

[Anonymous Coward]

This might seem randome. But, it sounds like you know a lot about the field I wish to Presue, I am using photoshop, flash, premiere, after effects, 3d studio max, maya and zbrush. I am interested in custome building a new desktop, my old one needs an upgrade. I have found the proccers I wish to use, but do not know which nvidia card to get. I see that this game written all over but what about animation and graphic art work. I personally will not game on my desktop, this is strictly for work. Can you please assist me. I do not have an account here is there a way to contact me out side this.

Re: And that type of battery is....

[Anonymous Coward]

Sorry, that respons was to your comment on the nvidia Titan

Wrong description

[folderol]

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!

Re:Wrong description

[thaylin]

Actually it is very descriptive. It remembers the last charge cycle and begins to memmic it which is different from the system just plateauing.

GODDAMNIT DURACELL

[Anonymous Coward]

Fuck you, Rabbit!!!

Re:GODDAMNIT DURACELL

[noh8rz10]

umm, the rabbit was energizer. Still going! nothing outlasts energizer.

Re:GODDAMNIT DURACELL

[Anonymous Coward]

nope, it was first introduced by Duracell and then re-used by Energizer, and only in the US at that. In Europe we've only had Duracell's.

Re:GODDAMNIT DURACELL

[Vicarius]

http://en.wikipedia.org/wiki/Duracell_Bunny

The Duracell Bunny campaign was launched in 1973 and predates the Energizer Bunny, which was created in 1989.

Re:GODDAMNIT DURACELL

[noh8rz10]

from your link:

In Europe & Australia the term "Duracell Bunny" has entered the vernacular as a term for anything that continues indefatigably while in North America the term "Energizer Bunny" has a similar connotation.

Never heard of the duracell bunny, so I guess it's a US/EU thing. this is one of the biggest dichotomies on slashdot, not apple/google/MS. Speaking of dichotomies, US Customary Units 4evah!

Re:GODDAMNIT DURACELL

[ChrisMaple]

In all the tests I've seen, Duracell has had a few percent advantage over Everready, or any other competitor. They simply make a better product.

Laptop batteries, anyone?

[toygeek]

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.

Re:Laptop batteries, anyone?

[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:Laptop batteries, anyone?

[Maximum Prophet]

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.

Re:Laptop batteries, anyone?

[sunking2]

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.

Re:Laptop batteries, anyone?

[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 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.
Batteries never actually used, but the laptop runs on AC power with the battery sitting there doing nothing? 100% of them will not hold a charge of any kind after 12 months of this "non-use".

Back in the 90's, there was Windows (3.11, wfw, NT, win95, win98) software available to exercise the battery while it was plugged into AC power. Such software allowed even ni-cad's to last for years without developing "memory" or losing run time. It allowed you to schedule a full discharge of the laptop battery weekly or monthly. Such software was also available for UPS's at the time. (Remember those UPS's that actually would run a computer for hours instead of minutes, yeah, those ones)

Since then, all such software has disappeared, and what do we have? Completely useless batteries in both laptops and UPS's, in under a year.

It's the same trend as printers and power tools. Consumables must cost more than the original unit and/or fail every year, minimum. Inkjet cartridges? Check! Power drill batteries? Check! Color laser printer toner? Check! Laptop batteries? Check!
When things in the PAST are worse than things in the PRESENT, and they perform the same task, it's not the advancement of technology that is to blame.
It's sociopath-run businesses wanting to turn everything into a service with an annual fee. Go-go-gadget free market consumerism!

My personal experience with laptop batteries has been that if they are fully/completely discharged to zero at least once a month, they last forever, regardless of all other usage patterns, elevation, humidity, temperature, make, model, or cell count.

Re:Laptop batteries, anyone?

[Ecuador]

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 battery which has a memory effect (in addition I assume to the effect I described that kills Li-Ion batteries).
If you want to make sure your Li-Ion batteries won't go bad, when you don't use charge (or discharge) them to 40% capacity and put them far from heat.

Re:Laptop batteries, anyone?

[Firethorn]

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.

Re:Laptop batteries, anyone?

[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.

Re:Laptop batteries, anyone?

[The Wannabe King]

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 a few days, and preferably only a few hours. The Leaf does not have active cooling (but the Model S has) which is not a problem in most climates. The batteries are still cooler than the laptop batteries that are stacked next to the CPU, at least in my laptop. The exception here is Arizona, as some Leaf owners have been unfortunate enough to discover. No problems after 21 000 km in Norway, though... there is still snow on the lawn!

Re:Laptop batteries, anyone?

[tibit]

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 the deterioration that leads to further raise of internal resistance.

Re:Laptop batteries, anyone?

[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....

Re:Laptop batteries, anyone?

[mikael]

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.

Re:Laptop batteries, anyone?

[Anonymous Coward]

So why don't the charge controllers handle this? Would it be that much more expensive? Do the designers want the battery to fail earlier so they can sell a replacement?

Re:Laptop batteries, anyone?

[tibit]

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 bypass. Never mind that most power supplies are not designed to properly work with a battery that has a dead cell in it -- even if it's entirely technically feasible.

Re:Laptop batteries, anyone?

[Immerman]

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 time, the further you get from half-charged the faster the battery degrades, and those suckers are under warranty.

My latest laptop battery has held a far more stable capacity since I adjusted the power settings to stay in battery-saving mode even when plugged in to AC, I rarely need the extra performance anyway, and can adjust the settings on the rare occasions when I do. As an added benefit the decreased heat and fan noise is more pleasant for me as well as for the battery. I just wish there was an option to not charge it beyond maybe 80% under normal circumstances.

Re:Laptop batteries, anyone?

[mybecq]

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.

Re:Laptop batteries, anyone?

[Anonymous Coward]

First, laptops don't use LiFePO4 which this paper concerns, so GTFO.

Second, not every form of battery deterioration is "memory effect", so you're full of horseshit. Educate yourself, then you'll understand what's going on. (Hint: laptop batteries mostly die because of because you're roasting them alive in a hot laptop.)

Re: Laptop batteries, anyone?

[Anonymous Coward]

my cheap crappy atom net book has an option to not charge beyond 80%. On the other hand it does need all the performance I can wring out of it...

Re:Laptop batteries, anyone?

[jittles]

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.

Re: Laptop batteries, anyone?

[Immerman]

Seriously? Sweet! What brand? I may have to look to them next time I need a rechargable gadget of some sort.

Re:Laptop batteries, anyone?

[bluefoxlucid]

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 :)

Re:Laptop batteries, anyone?

[bluefoxlucid]

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 compensate--worksite CD players run on 12.5-24V battery packs (as in the same exact model has ports for any of these and will compensate with fancy integrated circuitry). Usually computer equipment is prepared for this over a 5% deviation.

Re:Laptop batteries, anyone?

[Firethorn]

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.

Re: Laptop batteries, anyone?

[Anonymous Coward]

I know at least the Samsung Series 5 Ultrabooks have that.

Re:Laptop batteries, anyone?

[Anonymous Coward]

Exactly, kind of. Really the problem with any battery technology has always been about the charger, not the technology. But according to the news it's always the battery. Let us not forget that it is H1Bs that designed the crap we have now. Sure glad we saved that money!

Re:Laptop batteries, anyone?

[drinkypoo]

Holy shit someone is wrong on the Internet.

That's probably true, but nothing you said contradicted the parent, so I'm wondering who it is.

Re:Laptop batteries, anyone?

[ChrisMaple]

You're assuming the controller exists and is properly designed, which is a poor assumption.

Re:Laptop batteries, anyone?

[Osgeld]

I remember such software

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

Re:Laptop batteries, anyone?

[Anonymous Coward]

Computer and other high end electronics will typically have their own voltage regulators and not attempt to deal with a 5% or much of any swing in voltage where it matters. And with the push for efficiency, many of these are using switching power supplies as regulators, which can actually handle quite a bit of swing in voltage. The only thing they might skimp on is using a switching power supply design that requires a higher input voltage to run, when you can design one that will work with an input voltage that is too high or too low and still get the desired regulated output.

Re:Laptop batteries, anyone?

[Anonymous Coward]

The power management software on Lenovo Thinkpads lets the user set "start charge" and "stop charge" thresholds. For example, if "start charge" is 70% and "stop charge" is 80%, the battery will only begin charging if the state of charge is below 70% and the battery will never be charged above 80%.

I think some Sony Viaos have this feature too.

Re:Laptop batteries, anyone?

[Anonymous Coward]

My past three sony vaio laptops have this option.

Re:Laptop batteries, anyone?

[bluefoxlucid]

Actually what I said is if you shut off a cell, you no longer have the correct battery and shit doesn't work. You'd have to make the electronics work with it too, which requires more complex power supplies. Not impossible, but switching like that does have a cost and the battery life would be shorter to start with.

Re:Laptop batteries, anyone?

[tibit]

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 keep on working. Heck, my crazy-simple Philips electric toothbrush runs off a single cell and has a step-up switching power converter. I know for a fact that my Macbook runs just fine on a battery with two cells permanently bypassed by a wire.

Re:Laptop batteries, anyone?

[tibit]

Power supplies can be flexible at a nominal performance reduction when outside of the "sweet spot" and zero parts cost, if you just design them properly. Most laptops are extremely flexible and will work just fine over a supply range that spans 10V. You'll notice that for many laptops the external power supply provides a voltage much higher than the internal battery. There's just one internal power supply that can take either voltage, there's no extra step-down stage just for the external input. The design is optimized for best efficiency when running from the battery voltage, obviously.

Re:Laptop batteries, anyone?

[tibit]

Tell that to all those designers who make power bricks that take anywhere between 90 and 240 VAC on the input. Tell that to all those designers whose laptops happily run over a 10V or larger input supply range, by design. In other words: you have demonstrably no idea what you're talking about. None whatsoever.

Re:Laptop batteries, anyone?

[tibit]

Portable electronics use switching regulators almost exclusively since that's the only way to step down voltage without wasting lots of energy as heat. That's also the only way to step the voltage up -- whether the regulator uses inductors or capacitors as the energy storage buckets.

Sure there are small low drop-out regulators here and there, but the "low drop-out" is the key: those are the linear regulators that can do the job with just a couple tenths of a volt of overhead. You'll most likely not have an LDO powering any power hogs - the CPU, memory and chipset core voltages are all supplied by very tightly regulating switching regulators. Those switchers likely run from some intermediate voltage like 3.3V or 5V, of course.

As for acceptable voltage "swings": modern CPU cores will most likely barf at 5% changes in voltage. You have to regulate better than that, almost an order of magnitude better across load current spanning 95% of rated load. The CPU core power supplies are subject to a rather impressive array of performance tests designed by the CPU vendors, to ensure that the CPUs powered by those supplies will actually work. Modern CPUs are horrible loads: they can swing from tenths of an Ampere of load current to tens of Amperes in a millisecond -- and the other way.

anybody with an iThingie can tell you that

[swschrad]

and I wish you didn't have to hack your way in to replace them.

Re:anybody with an iThingie can tell you that

[Anonymous Coward]

and I wish you didn't have to hack your way in to replace them.

lol! Opening iCrap to replace a battery is not hacking. I guess I can understand why an apple user would think it is.

Re:anybody with an iThingie can tell you that

[Anonymous Coward]

I dont know. I have had my iphone 4 for around 3 years now and the battery still is good. Even though I mostly get partially charged two times a day to and from work, when I use it as GPS.

Re:anybody with an iThingie can tell you that

[Anonymous Coward]

Back when I was in my 20's, unscrewing a device, and lifting a battery to replace it wasn't considered "hacking"...

Re:anybody with an iThingie can tell you that

[Anonymous Coward]

Apparently now you cant just lift, you have to desolder.

Ha ha...

[UltraZelda64]

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.

Re:Ha ha...

[ledow]

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

Re:Ha ha...

[Anonymous Coward]

Seriously? My dad has used the same Li-Ion drill every day at work for over 2 years and only charges it when it's dead. Still runs like the day he bought it, he says. It should be noted that he does not baby his tools, and for anything to last him 2 years is an achievement, let alone a battery.

Re:Ha ha...

[Anonymous Coward]

Correct, that's how you should use them if you want them to last forever, regardless of type (ni-cad, ni-mh, li-ion, li-po).

Use it till it's dead, regularly, and it will work just fine forever. I have found this to be true, personally, for 20 years.

Re:Ha ha...

[tibit]

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.

Re:Ha ha...

[Immerman]

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 during normal use does both me and the batteries a world of good.

Re:Ha ha...

[UltraZelda64]

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 there in a nearby outlet... and then after a few months to a year they're having battery problem. It seems that the old "use down to 5-1% power before fully recharging" trick couldn't be working any better. Only rarely does the battery go 100% dead--I figure as rare as that in anyway, it can't hurt anything.

Re:Ha ha...

[viperidaenz]

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)

Re:Ha ha...

[Anonymous Coward]

that was ni-cad.

Re:Ha ha...

[bluefoxlucid]

The worst thing to do with a Li+ battery is to keep it fully charged.

Re:Ha ha...

[drinkypoo]

The worst thing to do with a Li+ battery is to keep it fully charged.

Unless you're semi-manually charging packs, the question is, how shitty is your device? Any decent device will just lie to you about charge status.

Re:Ha ha...

[Anonymous Coward]

Strictly speaking, discharging a Li-ion cell to zero should be OK, although maybe not the best thing to do every time. The main risk is with Li-ion batteries, where the weaker cells in a complete discharge end up being reverse-charged by the stronger ones. Li-ion cells really, really don't like being reverse charged, and will let you know explosively.

That's why single-cell packs are often just a single cell (albeit an oddly-shaped one), but multi-cell ones always have charge control circuitry built in.

Re:Ha ha...

[bluefoxlucid]

Keeping a cell phone or laptop plugged in 100% of the time, especially during use, is the fastest way to degrade the battery life.

Re:Ha ha...

[drinkypoo]

the question is, how shitty is your device? Any decent device will just lie to you about charge status.

Keeping a cell phone or laptop plugged in 100% of the time, especially during use, is the fastest way to degrade the battery life.

the question is, how shitty is your device? Any decent device will just lie to you about charge status.

Re:Ha ha...

[bluefoxlucid]

Modern laptops and top-end cell phones from Samsung, LG, and Motorola do this. Plug in your phone, pick it up, and start talking. It gets really hot. It also stays properly charged. It doesn't tell you it's 100% charged when really it's shut the charger off and is currently 80% charged. Note that the ideal charge under this condition is 70% or below--note that the Tesla won't charge the battery above 80% unless instructed.

Ideally the device would just shut off the charger and keep it below 80%. That doesn't actually happen. Worse still, even if your device keeps itself at 80% or below and calls that 100%, if it's continuously charging the battery while in use (i.e. if you don't get off the phone and find yourself at 80% reported battery life), the battery is experiencing degradation from being charged/kept charged while being used, thus being hot. The same occurs using a plugged-in $5000 laptop that's experiencing drain, even if it's cycling 10% of the charge or trickle-charging. Hint: Laptops trickle-charge, they don't charge cycle.

In the real world, any decent device will degrade the battery rapidly if put under load while plugged into the charger. Trufax. To avoid this, devices must keep the charge under 80%, and ideally allow for cycling down and back up over a wide range. Most ideally, you don't want to charge the battery when it's being drained heavily and is hot; but long-term use cases make this impossible in some situations (especially laptops; notably cell phones could dodge this by only charging when not in call or high data usage). Real devices provide the user with a guarantee that when they unplug and go they won't be at 50% of battery capacity; they don't provide the guarantee that the battery won't lose 50% capacity from being abused, just that it'll be topped at whatever its capacity is.

Re:Ha ha...

[stoploss]

This all seems very ass-backwards in terms of design. Why drain from the battery while it's plugged in? My HTC Incredible has taken this brain damage even further: the battery completes the circuit and the phone literally can't boot unless a battery is in place. If you are referring to modern devices like the Nexus 10 whose drain exceeds the charger supply, that's one thing.

However, let's talk about laptops then: there's no excuse for a laptop power supply to be less than the worst case draw of the laptop. As for cutting the battery out of the circuit: can't a power MOSFET (serving as a solid state relay) handle that much current? I seem to recall that Rds has gotten low enough that all the laptop's current wouldn't pose an issue... and switching the FET should take milliseconds or less, so power interruption wouldn't be an issue.

Also, I'm not sure that citing Telsa as an example of battery engineering is a good idea... considering they self-destruct their batteries if they aren't constantly plugged in. Hell, one $40k Telsa battery pack died because the owner had plugged it in via a 100+ foot extension cord. Sure, I^2R losses, but exactly how much power does the damn thing need to keep its head above water while it is sitting around, doing nothing?

Seriously now, I thought modern lithium technology had excellent charge retention. So, are they honestly claiming that they can't figure out how to shed vampire load on the goddamn car in state-of-charge emergencies and therefore just have no choice but to deplete the cells below 2.7V (or whatever)? It just can't be that hard... stop charge balancing if state of charge gets low, stop powering all the telecomms/gps/logging/computer crap, and the quiescent battery should be fine for a Long Time(tm), right?

I guess I am still annoyed at my Thinkpad killing my battery even though I practically never used it unplugged. Then one day I found it dropped charge from 100% to 0% in 3 minutes whenever it was on battery. Basically, what you're saying is that this could largely have been avoided if the engineers had designed the circuit to be able to cut the battery out of the loop while it was charged and the laptop plugged into wall power, right?

Re:Ha ha...

[bluefoxlucid]

Tesla now has a sleep mode, because prior firmware was fast-boot and would sit in a wait state eating 8% battery per day. You'd be surprised at the resistance of a 100 foot extension cord of fairly narrow gauge; it doesn't take much to completely stop 120V.

Re:Ha ha...

[stoploss]

Wow, that's not really a testament to Tesla's commitment to quality, because they shipped with that as a known issue (they documented it in the user manual as not covered by warranty). Their original workaround was to have the car phone home with a GPS report so that Tesla personnel could come out and help plug your car in for you. "We had to consume the battery in order to save it!" (*cough*)

Not exactly the pinnacle of sane engineering there. If your stat and Wikipedia's capacity specs are correct, then that's a vampire load of 175 W (8% of 53 kWh per day)—and they found that to be acceptable and reasonable? Even when the vehicle's battery was in dire threat of doom in terms of state of charge? There was nothing they felt like they could cut from that power budget, even in emergencies?

Yes, voltage drop over a long extension cord is expected when its under load. However, that's not the real issue: the actual problem was the "let's allow a daily 8% charge consumption while quiescent that leads to uncontrolled, fatal discharge, without understanding it is important to be able to shed load" engineering decision Tesla made. Furthermore, even the battery monitor IC's have a low-voltage cutout to protect the battery these days. I guess Tesla couldn't be bothered to follow industry standard practice in terms of power cell protection... better to just drive the $40k battery over the cliff, eh?

I mean, what's the expected, optimal, no-load, self-discharge rate for these cells under typical Tesla owner conditions (ie. garaged, or in California)? 10% per month?

Anyway, if what you said about devices needlessly killing their batteries while plugged in is true, then I hope that the engineers responsible for battery-powered products generally become less... "simpleminded" in terms of their perspective on battery circuits.

Re:Ha ha...

[bluefoxlucid]

Yes, they found it to be acceptable. You come home and keep your car plugged in, it stays at 80% charge, an 8% drain is not a problem. You throw in a 30A breaker and hook up the 10kW charging station and plug your car in. That was the use case. The use case for the Model S is not "refuel at the end of the week" because it takes 8 hours to refuel and if you suddenly need your car it's got 50 miles on it and you need to go 75.

It made sense in that configuration to drain the battery. I'm pretty sure the Tesla Model S has both overvoltage and undervoltage circuitry--it won't charge above 80% unless specifically instructed, at least. The battery is also warranted up to 100,000 miles or 8 years and should retain 80% or more capacity after that--that's 500 charge-discharge cycles.

Re:Ha ha...

[stoploss]

Really?

"Sorry, sir, it seems you left your Civic parked for several days with only 10% fuel left in the tank. I know that you're upset this caused $15k worth of damage to your car when the last of the fuel was finally burned while the car sat around parked... but if you refer to the 'sad face' icon next to the warning on page 327 of your manual, you see that this isn't covered under warranty. We warned you... and why would you leave your car like that in the first place? What were you thinking?"

It's not reasonable to engineer to "the happy use case"; the boundary conditions are more important—especially when those scenarios lead to damage! The fact remains that Tesla thought it was acceptable to allow the battery to fatally discharge itself which required a $40k battery replacement that wasn't covered under warranty. They shipped that as a known, documented bug when they could have (and later apparently did) prevented it via a (firmware?) update.

Anyway, it really seems to be either malice or incompetence on Tesla's part: malice, if they realized this would happen and just really wanted to ship before they could implement a fix; or incompetence, where they couldn't figure out how not to kill the battery while the car was sitting around unplugged. Either way, it's unacceptable. It doesn't matter if their happy use case involved the car being plugged in: there was no excuse for the car to damage itself if left unplugged.

You're the battery chemistry guru... tell me I'm wrong, and that there was some reason the Tesla Roadster had to kill its battery when it was left unplugged, and only some deep wizardry allowed Tesla to push a miraculous update that somehow amazingly prevented the battery pack from committing seppuku like the battery's chemistry naturally really wanted to force it to do.

I am not pleased with seemingly being forced to believe Tesla is malicious and/or incompetent, which is the only other possible conclusion. No one expects an uncharged EV to be able to drive, but they do legitimately expect the vehicle not to be permanently damaged by that condition.

If Tesla cut corners on this, then what else have they cut corners on?

Re:Ha ha...

[bluefoxlucid]

I dunno. Research says Tesla took many, MANY steps to prevent this, including advanced management systems that go as far as alerting the user. The car may discharge its battery completely if left in storage for a year; Nissan claims this isn't possible in the Leaf because of "an advanced battery management system that never lets the pack fully discharge, even when left in storage", so apparently Nissan solved the problem by trickle-charging the battery from a ZPM or Tony Stark's heart.

Re:Ha ha...

[stoploss]

Haha, awesome... "Help me, owner, I'm gonna die because I can't figure out how to stop draining my battery! I don't perceive the irony of consuming battery power to display this message, either!"

Haha, they also offered the option of having the car phone home with a GPS fix in order to dispatch the emergency "help you plug in your Roadster" crews too. All these "preventative measures" they tried appear to be a brain damaged, backward, insanely complex approach compared to the obvious solution of having the system simply shed all but trivial load/total shutdown/disconnect the battery via relay (had they designed one in)/whatever during a low-charge emergency.

Which apparently they figured out eventually, because they released an update to allow the vehicle to "sleep" now, right?

According to Battery University, it seems that a lithium ion battery at 40% charge level should retain 96% of its capacity after a year of storage at 25 C. So, it seems that simply removing *all* load (including state-of-charge monitors) after the capacity gets "low" (pick a value) and there is insufficient power to charge should prevent all damage to the battery pack. The further below the ideal storage charge level of 40%, the sooner a parked vehicle without charging power should enter emergency, total shutdown. This just cannot be that hard, and should have been patently obvious to anyone designing an EV's power system.

I guess that tips the balance for Telsa in favor of incompetence instead of malice. For whatever that's worth.

Re:Ha ha...

[bluefoxlucid]

The "Sleep" mode is an optional, non-default mode for preserving range. It activates when it's been configured, so that you don't lose 16 miles of range per day.

can be fixed with software change

[Chirs]

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.

No shit Sherlock

[Anonymous Coward]

This should have been listed as "from the no-shit-Sherlock dept." I, and numerous others, have been saying for years that all those claims that li-ion batteries don't suffer from memory effect are bullshit. The aftermarket laptop battery market would be almost non-existent otherwise.

Re:No shit Sherlock

[Immerman]

Degradation with time and usage != memory effect. Memory effect is a specific kind of degradation due to partial charging or discharging. For example if you recharged a NiCd battery that was only down to 50% charge you would immediately and permanently reduce it's total capacity, hence the tendency of those "in the know" to drain the batteries completely before recharging them.

DUH! I Could Have Told You That!

[Anonymous Coward]

Any consumer could have told you that!!! If you haven't noticed your lithium batteries not lasting, not holding a charge then pinch yourself and put down the crack pipe!

Just in: Rechargable batteries suck!

[Anonymous Coward]

I don't think I've ever owned a rechargeable battery (of any chemistry) that lasted even 10% of the claimed recharge cycles.

Why aren't rechargeable batteries real world tested by a hard core standards body that kicks battery makers in the nuts and berries when 'ideal lab conditions' don't measure up to actual usage?

Re:Just in: Rechargable batteries suck!

[BitZtream]

Because you're treating your batteries like shit.

Lead Acid batteries (like you car battery) are pretty fucking hard to kill outside of the environment your car subjects them too (heat is a bitch), even that, how many times have you warranty replaced your car battery?

NiCads are relatively resilient. You can certainly hurt them, but you have to do 'known bad' things that every manual and charger label probably has written on it. Don't drop them below 1.2v per cell, keep them cool during charging (heating means you're doing it wrong). I've had high quality packs for my R/C cars last 5 years. First year as 'race' packs, then the next several as warmup/fun packs. You're talking 250-500 charge cycles of extremely harsh use. That is at least 10% of the nicads expected life under what most would consider some of the harshest possible conditions for the batteries to be in. High current discharge while basically laying on an asphalt road way in the Florida sun, to be immediately thrown back on a charger for the next round without letting it cool or anything. Not even needed to memory cycle the batteries, my usage patterns were so harsh they didn't have the time to build up memory before they were shot anyway.

My previous laptop was an amazing example of excellent battery in my eyes. I retired it in the middle of last year, almost exactly 3 years to the day after purchase and it was used from full charge to nearly depleted extensively during that period as my workstation. I admit, towards the end it was getting short, but certainly well past the 80% at 400 cycles. My wifes laptop on the otherhand won't hold a charge for shit and its only 2 years old! Of course, its been sitting with a charge connected to it for its entire life time, which is a horrible thing to do to a Li-Ion.

Re:Just in: Rechargable batteries suck!

[QQBoss]

'94 Ford Taurus SHO stick, daily driver for about 15 years: I replaced the battery about the middle of every Texas summer- yeah, heat kills, but still, in spite of buying 60+ month batteries. Had a vampirism problem with a faulty alarm that took out two in one year, but other than that, eating batteries was just the price I paid for the enjoyment that car gave me.

Strangely enough, I am using an ACER notebook now that I keep plugged in probably 80% of the time that I use it (and, yes, I know better, I just don't care enough to change). The battery life is down only 20% over when I bought it close to a year ago. I am thinking that the BIOS might be limiting the battery charge to 80% to slow down the destruction of the battery, because I didn't get the expected life out of the battery compared to my previous notebook at the start, but at the one year mark and same usage pattern, this Acer is doing much, much better.

Ping Battery

[Slashdot Parent]

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 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!

Forget the batteries...

[MugenEJ8]

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...

Discombobulating multiple issues

[WaffleMonster]

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.

Re:Discombobulating multiple issues

[BitZtream]

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

'Deep cycling' won't fix the issue and make your battery last longer suddenly. It will just cause the gauge to understand that your battery is no longer new and is now rather shitty indeed.

Re:Discombobulating multiple issues

[WaffleMonster]

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.

Pitty A123 died then eh?

[viperidaenz]

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

Re:DUH! I Could Have Told You That!

[viperidaenz]

There's a difference between the memory effect and the battery wearing out. It is known that a lithium battery will wear out. They even wear out while in storage. Especially when warm and fully charged.

Tesla doesn't use LiFePO

[YesIAmAScript]

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.

Memory free batteries don't exist

[BitZtream]

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.

Re:Memory free batteries don't exist

[spongman]

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

"bump" charging, anyone?

[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....

Or the designers *did* put that in but then took it out after too many complaints from users about their cellphones being less than 100% charged after having been plugged in to the charger overnight. http://www.androidpolice.com/2010/12/14/your-battery-gauge-is-lying-to-you-everything-you-need-to-know-about-bump-charging-and-inconsistent-battery-drain/

Just another reminder that for some applications users would much prefer a battery that lasts longer on a per-day basis over one that has a longer total lifetime.

This is deprecated.

[Anonymous Coward]

You can easily and cheaply print graphene super capacitors using nothing more than graphite and a light scribe dvd burner. It may take a couple of years, but the battery is effectively rendered useless now.

So much stinking bullshit here

[metaforest]

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. The only way to avoid that is if you manage the charge cycle yourself.

Funny... I have a 2001 Apple Ti-book... It is on its second battery pack(the first one was killed by keeping the system in storage for over a year without any charge). I have never taken any special precautions for the battery, other than to make sure it gets FULLY recharged ASAP after a discharge cycle. It spends many months at a time in sleep mode, and is only off AC a few times a year. The battery in it now was purchased new over 7 years ago... It still holds 4 - 5 hours of capacity under conservative loads. This is about 20% less than what it did new.

The reason this is so, is that:
1. The charging system was designed not to abuse the battery in any way.
2. The battery is mounted in a location in the chassis that is not subject to heating from other system components.

Conclusion after 12 years of use? The battery chemistry is not the problem. PEBCAK, and shitty engineering kills batteries.

re:

[Anonymous Coward]

I never believed in the "no memory effect" since all of my Lithium-ion batteries seem to demonstrate it