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Subject: Re: to weak batteries - cant even charge... ;-(
From: Linus Nielsen Feltzing (
Date: 2004-09-18

VanBaren, Gerald (AGRE) wrote:
> IMHO (and everybody has different opinions on this topic), you are
> being too cautious. You can see the charging current vs. charging
> adapter voltage in:
> NiCd battery
> manufactures univerally (at least in my limited universe) list 1/10
> AH rating of the battery to be the safe continuous charge level. For
> 1800mAH batteries (supplied by Archos), that would be 180mA which is
> approximately what a 9v adapter (supplied by Archos) would provide.
> This probably is no coincidence.

First of all, the batteries supplied by Archos are 1500mAh, which would
give a charging rate of about C/8 with the standard adapter according to
the FAQ. Secondly, if you, like many others, use a regulated 12V supply
to charge, you will have a charging current of 350mA, which is roughly C/4.

> What this means to me is that I can charge at full tilt for long
> periods (much more than 5 minutes) before worrying about
> overcharging, especially if I have a 9v adapter and/or higher
> capacity batteries. With high capacity batteries, it is getting
> close to impossible to "overcharge" the batteries even with a higher
> voltage adapter.

I agree that we could charge for a few minutes regardless of battery
capacity or charger voltage. It is definitely possible to overcharge the
batteries, though, so we still need a clever charging algorithm.

> Note that undercharging batteries is harmful to them also, not to
> mention frustrating to the users :-(.

Absolutely. I think we should change the FAQ, to specifically not
recommend 9V regulated adapters since they charge too slow, especially
when you have high capacity batteries.


Page was last modified "Jan 10 2012" The Rockbox Crew