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Karel Jansens is offline Karel Jansens
2008-05-07 , 08:42
Posts: 3,220 | Thanked: 326 times | Joined on Oct 2005 @ "Almost there!" (Monte Christo, Count of)
#11
Originally Posted by Iceman0124 View Post
Its not a good idea to leave any l-ion battery plugged in after its fully charged, it shouldnt overcharge, but all l-ions have a finite number of charge/discharge cycles, when the battery is fully charged, while plugged in it will stop charging, it will slightly discharge, then recharge, rapidly consuming the limited number of cycles. Thats why laptop owners that spend 99% of their time with it anchored to a wall are often dismayed on that rare occasion they take it out unteathered and think they got screwed with a bad battery.
Actually, the number of recharge cycles (which is an educated guess, really) pertains to complete recharges, meaning that if you never let your battery drain beyond 50%, you should get roughly double the recharge number. "Roughly" implying here that there are so many other factors playing that you'd get laughed at if you complained about getting only 590 instead of 600 cycles. Also, tricle-charging is designed to have as little impact on the battery as possible.

LiIon's biggest enemy is the al-gorean climate of the car seat: Leaving your laptop in your car in the sun is enough to reduce its battery quality to an AA (provided the idjit who leaves a laptop on a car seat finds it even back upon returning, that is).
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Benson is offline Benson
2008-05-07 , 14:08
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#12
Originally Posted by Iceman0124 View Post
Its not a good idea to leave any l-ion battery plugged in after its fully charged, it shouldnt overcharge, but all l-ions have a finite number of charge/discharge cycles, when the battery is fully charged, while plugged in it will stop charging, it will slightly discharge, then recharge, rapidly consuming the limited number of cycles. Thats why laptop owners that spend 99% of their time with it anchored to a wall are often dismayed on that rare occasion they take it out unteathered and think they got screwed with a bad battery.
Li-ions are generally much more affected by time than by cycles; heat, as the General says, is a real killer, but it works by affecting the time rate of degradation. That's why they say to keep spare batteries in the fridge or freezer.

Also, charge state does affect the rate, so leaving it on the charger, hence always ~full, is slightly worse than cycling it down to near empty, and fully charging it; but not (substantially) because of the discharge/recharge cycles.
 
Karel Jansens's Avatar
Karel Jansens is offline Karel Jansens
2008-05-07 , 19:35
Posts: 3,220 | Thanked: 326 times | Joined on Oct 2005 @ "Almost there!" (Monte Christo, Count of)
#13
Originally Posted by Benson View Post
Also, charge state does affect the rate, so leaving it on the charger, hence always ~full, is slightly worse than cycling it down to near empty, and fully charging it; but not (substantially) because of the discharge/recharge cycles.
Actually... Regular deep discharges are just about the second worst thing you can do to a LiIon (second to leaving it in the blistering heat, that is. If you also count poking inside them with sharp metal objects, then it's the third worst thing). They stay much happier when topped off before reaching half discharge.

Remember: LiIons are a completely different beastie than NiCads; the latter really craves the deep discharges.
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GeraldKo is offline GeraldKo
2008-05-07 , 19:49
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#14
Originally Posted by Karel Jansens View Post
Actually... Regular deep discharges are just about the second worst thing you can do to a LiIon (second to leaving it in the blistering heat, that is. If you also count poking inside them with sharp metal objects, then it's the third worst thing). They stay much happier when topped off before reaching half discharge.

Remember: LiIons are a completely different beastie than NiCads; the latter really craves the deep discharges.
Hmm. I don't know what this did to the lifespan of my battery, but ...

It was starting to say Fully Charged rather quickly and then not showing that it had a lot of juice when I took it off the charger, and, indeed, it did seem to run out pretty quickly. So I did a total discharge, until it turned itself off, and subsequently it seems to take a much larger charge. Maybe that's theoretically true only for NiCads, but my experience seemed to show it worked for my N800's LiOn battery.
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Karel Jansens's Avatar
Karel Jansens is offline Karel Jansens
2008-05-07 , 20:49
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#15
Originally Posted by GeraldKo View Post
Hmm. I don't know what this did to the lifespan of my battery, but ...

It was starting to say Fully Charged rather quickly and then not showing that it had a lot of juice when I took it off the charger, and, indeed, it did seem to run out pretty quickly. So I did a total discharge, until it turned itself off, and subsequently it seems to take a much larger charge. Maybe that's theoretically true only for NiCads, but my experience seemed to show it worked for my N800's LiOn battery.
LiIons have a funky charge cycle. They go up from near empty to showing almost full capacity very quickly, but most of that is "ghost" capacity; if you don't let the charge cycle complete itself, you'll end up with what you might think is a defective battery. This is another reason why it's good to "top off" LiIons: You get less of the ghosting effect if you unplug them too soon.

So, if possible let the charge cycle complete itself (for the Itablets that means: Wait until the battery icon shows full capacity), especially in case of a deep discharge.
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Benson is offline Benson
2008-05-07 , 20:59
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#16
Originally Posted by Karel Jansens View Post
Actually... Regular deep discharges are just about the second worst thing you can do to a LiIon (second to leaving it in the blistering heat, that is. If you also count poking inside them with sharp metal objects, then it's the third worst thing). They stay much happier when topped off before reaching half discharge.
Well, depends what you mean by "deep"; I was thinking perhaps down to 30%; anything below that is just plain scary, as well as perhaps harmful... I thought that was okay, though obviously pointless.
Remember: LiIons are a completely different beastie than NiCads; the latter really craves the deep discharges.
Yes, which is why a flashlight is a valuable accessory for NiCds; I will not run any battery very deep in devices when avoidable, so I periodically throw a random pair of (semi-used, waiting for recharge) batteries in a flashlight, turn it on, and put my solar-powered watch in front of it to recharge overnight. In the morning, batteries are cleansed, and watch is full. (And atomic synced, since I do it on a windowsill.)
 
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