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i bought a 3500mAh Li-ion battery for my htc evo and it came with some puzzling instructions about requiring 'conditioning' for best performance. basically, it recommends doing a complete discharge five or six times "before even thinking about plugging in your cell phone when you still have battery power left."
another line near the end reads "continue to drain your cell phone battery completely before plugging it in at every available opportunity."
this goes against everything i've ever read about Li-ion batteries having no memory. and it goes completely against what i read here about avoiding complete discharges
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However, be sure to avoid fully draining/discharging the Li-ion battery as much as possible; every time a Li-ion battery is fully discharged, it loses battery power and life. (That doesn't mean your battery will die if it is ever fully discharged; it means it is best to avoid fully discharging when possible.) Try to recharge Li-ion batteries when they are at 15-25%. Similarly, avoid heat as much as possible and when (if) storing Li-ion batteries, store them not at full charge. Tip: Condition your new cell phone’s battery to make it last longer (but be sure to condition it properly) | Tips 'n Tricks | dotTech
so should i ignore what the instruction manual says, or should i do repeated cycles of fully charging/discharging?
The whole thing about "drain completely before you recharge" is still sound advice, though not as critical as it once was. With a Li-Ion it has nothing to do with memory, but with the number of charge cycles in the battery's lifetime.
A typical LiIon battery has 300 - 500 charge cycles in its life. Some have more, some have less, but that's a good general average. That means that if you charge your phone every day, your battery should last you around a year, give or take a few months. But if your phone doesn't need charged every day, you can extend your life even further. If you only charge every other day, suddenly your battery lifespan is more or less doubled. The opposite end of course is folks who charge overnight, wake up, plug in on the way to work, plug in at work, plug in on the way home from work, and plug in as soon as they get home. That's four charge cycles daily; the battery will start to trail off after only 3-4 months.
As for brand new batteries, I always do a full discharge / full charge the first few cycles. Just an old habit, I guess.
The whole thing about "drain completely before you recharge" is still sound advice, though not as critical as it once was. With a Li-Ion it has nothing to do with memory, but with the number of charge cycles in the battery's lifetime.
A typical LiIon battery has 300 - 500 charge cycles in its life. Some have more, some have less, but that's a good general average. That means that if you charge your phone every day, your battery should last you around a year, give or take a few months. But if your phone doesn't need charged every day, you can extend your life even further. If you only charge every other day, suddenly your battery lifespan is more or less doubled. The opposite end of course is folks who charge overnight, wake up, plug in on the way to work, plug in at work, plug in on the way home from work, and plug in as soon as they get home. That's four charge cycles daily; the battery will start to trail off after only 3-4 months.
As for brand new batteries, I always do a full discharge / full charge the first few cycles. Just an old habit, I guess.
but doesn't that still go against the whole 'lithium batteries have no memory' thing? the number of charge cycles shouldn't matter at all, if they truly have no memory.
but doesn't that still go against the whole 'lithium batteries have no memory' thing? the number of charge cycles shouldn't matter at all, if they truly have no memory.
Here's the deal.
There is a universe of misinformation about the whole "battery memory" thing. Otherwise intelligent people will swear up and down that they "opened up their laptop / cell / camera / etc battery and saw a memory chip in there". The battery doesn't have a memory; it can't "remember" what its previous charge state was when the last charge cycle was initiated. Rather, it's simply the action of a predictable physical phenomenon.
The "memory effect" has to do with crystalline structures forming on the nickel plate (and in the case of NiCd, on the cadmium electrode as well). To make a long story short, these get formed when the battery is overcharged, when the battery is repeatedly charged without a full discharge, or when a battery sits unused for a very long time. While these old NiMH and NiCd batteries do have a finite number of charge cycles, the truth of the matter is that abuse of the battery will cause its useful life to end long before this cycle limit is reached.
These crystalline structures do not form in a lithium ion battery, making LiIon batteries immune from the "memory effect". However, like every other consumer battery ever made, they do have a finite number of charge cycles. A LiIon battery using a cobalt cathode (the most common type today), this is around 500 cycles. Manufacturing variances and materials quality can push this by a few hundred cycles in either direction. A poorly-made LiIon might only see 300 cycles before performance degrades noticeably, while a high-quality LiIon could see 700.
There's a relatively new type of LiIon battery using NMC (nickel-manganese-cobalt) as the cathode. It can deliver a useful charge cycle life of around 1500 - 2000 charges. This is the type you'll find in modern electric vehicles or hybrids like the Sonata.
Like everything else in life, a LiIon battery has a finite life. It's not the "memory effect", it's simply wearing out.
The opposite end of course is folks who charge overnight, wake up, plug in on the way to work, plug in at work, plug in on the way home from work, and plug in as soon as they get home. That's four charge cycles daily; the battery will start to trail off after only 3-4 months.
conflict with this?
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The battery doesn't have a memory; it can't "remember" what its previous charge state was when the last charge cycle was initiated.
the first states that it does remember the number of charge cycles, and that the life of the battery is simply a function of the number of times it has been allowed to charge.
the second says it does not.
to ask the question another way: does 'topping off' the battery shorten the lifespan of the battery, or doesn't it?
the first states that it does remember the number of charge cycles, and that the life of the battery is simply a function of the number of times it has been allowed to charge.
the second says it does not.
to ask the question another way: does 'topping off' the battery shorten the lifespan of the battery, or doesn't it?
I wouldn't think so. I think that two 100% to 40% to 100% cycles would be roughly equivalent to one 100% to 20% to 100% cycle.
I could be wrong, but that is my impression based on how hybrid cars supposedly maximize their battery life through programming to operate in a charge range of, say, 40% to 80% of theoretical capacity, rather than push it farther in either direction. Even if the vehicle could be pushed to get even better performance or mileage, manufacturers don't because it would come at the expense of battery pack longevity.
Hmmm. I wonder if cell phone battery longevity would go up if only charged up to say, 90% instead of 100%, and never discharged below 30%. I'm not going to be the one to find out though. I'll take all the run time I can get from of my HTC Thunderbolt.
Last edited by Thegonagle; 01-03-2012 at 08:46 PM..
to ask the question another way: does 'topping off' the battery shorten the lifespan of the battery, or doesn't it?
Yes. But it's not the "memory effect".
I don't know how else to explain this, but I'll try one more time.
The "memory effect" described a phenomenon where if you frequently ran a Nickel-Cadmium battery down to 50% of its capacity before charging, its 50% would become its new 0%. Thus, your battery capacity would be halved. This happened to some extent with Nickel Metal Hydride batteries, but it was somewhat mitigated.
This does not happen with Lithium Ion batteries. A LiIon battery will eventually wear out and show diminished capacity, but that's a factor of the number of charge cycles.
In other words, all other things being equal, a LiIon battery that gets fully recharged every time it reaches 70% charge will last for just as many charge cycles as a LiIon battery that gets fully recharged every time it reaches 10% charge. The LiIon will not degrade simply because you didn't fully discharge before charging. It will degrade simply because it was charged.
This differs from NiCd / NiMH batteries, which will degrade if not properly drained / managed before charging (aka the "memory effect").
The two are completely different phenomenon. EVERYTHING wears out over time. There is no such thing as a battery that will last forever But just because a battery loses some of its charge capacity doesn't mean it's affected by the memory effect.
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the first states that it does remember the number of charge cycles
I never said it remembers the number of charge cycles. I said it simply wears out. Your average battery cell has no way of knowing how many times it's been charged, it simply loses a little capacity each time.
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