From: Jammit Timmaj <jammit999_at_hotmail.com>
Date: Wed, 7 May 2008 19:36:57 +0000

> Date: Tue, 6 May 2008 11:03:34 -0500
> From: mark_at_allums.com
> To: rockbox_at_cool.haxx.se
> Subject: Re: My first post... and question.
>
> Jammit Timmaj wrote:
> >
> >
> > I figured the battery capacity was more a guess than a science because
> > the actual battery itself doesn't have any built in electronics for
> > detecting charge state like a laptop battery does. Consider this
> > question answered. Thanks.
> >
>
> Actually if it's a LiIon battery, it probably *does* have a chip. (I
> would be happy to be wrong about this.) Whether the iPod uses it, I
> couldn't guess. If Rockbox relies on a hard-coded value for the
> capacity, charging could get ugly if the battery is replaced with one
> that has less capacity. Or as Dell laptop owners like to say, "Boom!"
> Makes me glad the Sansa e200 code uses the original firmware for charging.
>
> --
> Mark Allums

Hey, I have a Dell and it still "mostly" works...

The 1st gen iPod I have was given to me broken (fell off a car on the highway at speeds of 60 mi/h). The HD was bad and the original battery was simply old. A new HD fixed the machine, and the new battery was added as a bonus (new chemistry, longer runtime). Unfortunately those were the only things broken on it and I never had to test the battery charging circuit or anything else. If I did have to fix those I would know more about how it works.

There /is/ a chip, but it doesn't "speak". It only protects the battery during charge/discharge. Kind of like a smart fuse. It has no outside communication. I thought battery life was estimated in software and learned the battery behavior. I believe the main guts of the iPod only regulates the firewire 12V down to something like 5V, then the chip on the Li+ battery regulates the power going into the battery. I'm sure the MAX1555 is a similar chip:
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4002

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Received on 2008-05-07