On Mon, 4 Jul 2005 00:37:21 +0100, Richard Urwin wrote > On Saturday 04 Jun 2005 11:24 pm, Ian wrote: > > On Saturday 04 Jun 2005 20:12, Mikkel L. Ellertson wrote: > > > Ian wrote: > > > > On Saturday 04 Jun 2005 18:36, JR wrote: > > > > > > > > I'd expect a laptop to last at least 5 years without repair. > > > > Either you are extremely ham fisted or you bought a dud. > > > > Laptop batteries aren't known for longevity, although completely > > > > discharging them is a sure recipe for failures (the charger > > > > usually can't bring it back up from zero). > > > > > > I find this interesting, because the directions for the Li-Ion pack > > > for my Thinkpad recoment doing a full cycle to full discharge, and > > > then full recharge every 3 months. The instructions for the Ni-Cad > > > recoment doing it at least monthly. I am not sure about systems > > > using Ni-MH batteries... > > > > Yeah, thats what the instructions here said as well.......... > > Full discharge (left on by mistake a couple of times) resulted in the > > pack not working . The manufacturers agents claimed this caused the > > failure and advised us not to let it go 10%. > > NiCd (and to a much smaller extent NiMH) batteries suffer from > memory effect. If you charge them from anything but zero they > remember and run out at that point the next time around. It is vital > with NiCd batteries to only do full recharges if you can manage it. > If the battery does fail that way you can often recover them with > repeated full cycles. > > So, so far as I can see the agents' instructions were a recipe to > force a failure if the batteries were NiCd, and none too safe if > they were NiMH. If the charger wouldn't charge from zero I'd demand > a refund.
NiCd - memory effect. Full discharge and full charge should be part of their regular life cycle. Continuous partial charging and discharging will shorten their usefulness in no time. NiMH - no significant memory effect (or so I'm told). But it doesn't hurt to fully drain and fully charge during regular use either. Best part about NiMH is the higher capacities and quicker charging that goes with it. I treat them the same as NiCD. Li-Ion - no memory effect what so ever. Go ahead and top em up when ever you feel like it. DO NOT DRAIN LI-ION BATTERIES DEAD. This will kill them sure as I'm typing. The current state of consumer Li-Ion batteries will not tolerate full discharge, or excessive discharge, or excessive heat, or over-charge, or etc... Let's be honest, they're just plain delicate. That's the price you pay for a high tech, light weight, high capacity power source. No having said that, "most" new consumer devices contain circuitry to prevent the battery from discharging to zero, so you couldn't kill it if you wanted. In some cases, the protction circuitry is built right into the battery itself. However I wouldn't try draining Li-Ion batteries dead unless you've got clear proof that the device you're using has an appropriate internal protection circuit. I repeat DO NOT DRAIN LI-ION BATTERIES DEAD, unless your equipment is built to cut you off before the batteries die. Scott -- Nothing goes to waste when Little Fish are near! (http://www.littlefish.ca)
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