Constant charging of LiIon battery (was: Re: Can my FreeRunner remind me to shut it down if it is still running at 22:00?)

[Paul Fertser]

Ben Wong <lists.openmoko.org at wongs.net> writes:
>> Yes, this is what I was thinking of. I am afraid to leave battery-powered
>> devices plugged in (line-powered) all the time, though, because doing so
>> seems to kill laptop batteries.
>
> That's a good question, whether constant charging shortens the
> lifespan of a Li battery, which I'm sure someone more knowledgeable on
> this list will answer.  From personal experience, I believe that to be
> true.

Same for me, i believe my laptop battery was killed by constant
charging. Other reports and advices found on the internet suggest that
to be the likely case.

For FR, however, there shouldn't be much concern as it cuts off
charging the battery as soon as it's full and then reenables the
charging at approx 75-80%. Ensure you use a recent Qi (at least 2 Jun
2009) because if you don't the PMU might not detect battery full
condition properly due to GSM modem drawing power directly from the
battery terminals.

I'm currently working on patches to finally bring sanity to the
charging/discharging batteries on FR, including dumb batteries (yes,
you can use your favourite dirt-cheap BL-5C now and you'll even see
how much charge is left there), so stay tuned.

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