Re: Completely discharging LION batteries

[Jochen Reinwand <jbr.1-hi6Y0CQ0nG0@public.gmane.org>]

> > > I'm using Linux 2.4.20 together with the acpi patches
> > > 20021205-2.4.20 on a
> > > Thinkpad T20. If I use two batteries (the builtin and a
> > > second in the Ultra-
> > > Bay), the second battery first gets discharged _completely_
> > > and after that the internal battery is used.
> >
> > That's normal, but yes it is not the smartest idea to do.
>
> What I'm wondering about is that in the Windows 2000 Help of
> the Thinkpad Laptop, IBM advises that it is better to discharge
> the battery sometimes completely to refresh the full capacity
> at least partly. That advise is completely the opposite of what
> I've seen. But it could be an mistake in their documentation or
> they could target NiMH batteries.

Interesting informations about Li-ion batteries can be found at 
http://www.buchmann.ca/. It seems to be not available at the moment. But here 
are a few tips from the page:

- Charge the Li-ion often, except before a long storage. Avoid repeated deep
  discharges.
- Keep the Li-ion battery cool. Prevent storage in a hot car. Never freeze a
  battery. 
- If your laptop is capable of running without a battery and fixed power is
  used most of the time, remove the battery and store it in a cool place. 
- Avoid purchasing spare Li-ion batteries for later use. Observe manufacturing
  date when purchasing. Do not buy old stock, even if sold at clearance
  prices.

But there is also a note on the site that a deep discharge cannot bring back I 
higher full charge level. On this list I once found the tip that it should
work. I tried it and my battery was again able to charge to full capacity.
btw: DO NEVER COMPLETELY DISCHARGE A LI-ION! Normal electronic devices can not 
discharge a Li-ion completely. So it should be ok to discharge until the 
device powers of. There is still enough power in the battery to lit a lamp 
for a long time. But that would discharge it definitively to low!

Jochen


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