From mboxrd@z Thu Jan 1 00:00:00 1970 From: pavel@ucw.cz (Pavel Machek) Date: Fri, 18 Dec 2009 09:48:50 +0100 Subject: [POWER] battery calibration parameters from sysfs In-Reply-To: <4B28AAFC.5010108@warmcat.com> References: <20091207165628.GA24981@rakim.wolfsonmicro.main> <20091213132413.GB1437@ucw.cz> <20091214121247.GB22388@rakim.wolfsonmicro.main> <20091214212257.GA9213@elf.ucw.cz> <4B26FC52.6060307@billgatliff.com> <1260919938.10441.18.camel@utx.utx.cz> <4B28AAFC.5010108@warmcat.com> Message-ID: <20091218084850.GA1513@ucw.cz> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi!1 >>> Yes, but in that case you might as well just purchase a coulomb >>> counter with a built-in accumulator and an I2C/SPI/microwire interface >>> save yourself some PCB space and cost (maybe) Hardware is already given. >> Well, Pavel attempts to implement a "poor man's Coulomb counter" or at >> least "poor man's Ampere meter" for devices that are not equipped with >> any of it. > > I think the "poor man's Coulomb counter" is a loser, the errors will > overwhelm you too rapidly. The estimated rate of discharge could >> work, Actually android phones do "poor man's Coulomb counter", and it seems to mostly work. > based on what clocks, regulators and so on are running, but I am not > sure how useful that number is really given you can't realistically > integrate it due to the big error it is bound to have. ... > Otherwise for L-ion batteries, looking at the voltage level alone, > filtered to remove GSM transmit slots etc, is really quite workable for > estimating charge status. Well, you have to compensate for backlight power; and yes, that's what I'm trying to do. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html