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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."
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.
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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.
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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.
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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.
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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.
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* 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.