linux-kernel - Re: [POWER] battery calibration parameters from sysfs

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Message-ID: <20091214212257.GA9213@elf.ucw.cz>
Date:	Mon, 14 Dec 2009 22:22:57 +0100
From:	Pavel Machek <pavel@....cz>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	Linus Walleij <linus.walleij@...ricsson.com>, cbou@...l.ru,
	dwmw2@...radead.org, LKML <linux-kernel@...r.kernel.org>,
	linux-embedded@...r.kernel.org,
	Brian Swetland <swetland@...gle.com>, rpurdie@...ys.net,
	lenz@...wisc.edu, Dirk@...er-Online.de, arminlitzel@....de,
	Cyril Hrubis <metan@....cz>, thommycheck@...il.com,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	dbaryshkov@...il.com, omegamoon@...il.com, eric.y.miao@...il.com,
	utx@...guin.cz, zaurus-devel@...ts.linuxtogo.org
Subject: Re: [POWER] battery calibration parameters from sysfs

Hi!

> > > I'm not sure how familiar you are with the issues surrounding trying to
> > > do a voltage to charge mapping for a battery but it's much more complex
> > > than a simple table if you want to get it accurate.  There's a lot
> > > of
> 
> > Well... current zaurus kernels use _huge_ table that maps voltage to
> > battery %... and that table is linear function :-(.
> 
> > Do you have some papers on that?
> 
> Something like "Measure Battery Capacity Precisely in Medical Design"
> by Bernd Krafthoefer in Power Electronics Technology Jan 2005 might be
> useful here.

Well, that would really require extensive hardware modifications: it
needs _way_ more accurate ADCs on battery for a start, and a way to
generate huge load.

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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