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Rockbox mail archiveSubject: Re: Re[3]: battery measurementRe: Re[3]: battery measurement
From: Andrew Jamieson <andrew.jamieson_at_projectlab.net>
Date: Thu, 19 Sep 2002 18:13:10 +1000 This is what allot of laptops do, with a circuit integrated into the battery itself (often referred to as a 'gas guage' circuit). They precisely monitor the current in and out of the battery over its life, often compensating the remaining charge reported with respect to the age of the battery, and even how 'badly' it has been treated. Maxim and Benqmark make such circuits (such as the MAX1780). However, they are always, IMHO, quite inaccurate after only several months of use.... The problem with doing this ourselves in the Rockbox code, is that we don't have the accuracy of a gas gauge, and we can't predict what the user will do. As we all know from the current measurements, if the user suddenly decides to start skipping through tracks and browsing the menu (using extra HDD and backlight), the time remaining will plummet .... Also, batteries 'wear' over time. I know, for instance, that my Archos often shuts off due to low power when there is still one bar on the meter. This is because my batteries are over a year old, and I often leave my unit plugged in to the wall for varying lengths of time (from days to minutes). Put succinctly, my batteries are screwed. Allot of peoples are. Also different people have different mAh batteries (1500, 1800, there are even 2000 you can get now). What you propose will probably work, for a few months, for any one persons unit; if the values are tailored specifically to their setup. I can't see us finding values that work. both accurately and precisely, for the whole community. However, I hate being a nay sayer, so give it a try! My nasty batteries and I are always happy to be guinea pigs :) Andrew Jamieson ----- Original Message ----- From: "Olivier BUTLER" <obutler_at_unim.fr.memec.com> To: <rockbox_at_cool.haxx.se> Sent: Thursday, September 19, 2002 5:35 PM Subject: RE: Re[3]: battery measurement > > The only way to get an accurate value of the remaining time is to monitor > the current during charging and discharging ( in use ) , then calculate the > amount of energy ( kJ ) in the battery. ( Some electric shaver to that ). > > Olivier > > > > -----Message d'origine----- > De : Tjerk Schuringa [mailto:regenpak_at_yahoo.com] > Envoye : jeudi 19 septembre 2002 07:51 > A : rockbox_at_cool.haxx.se > Objet : Re[3]: battery measurement > > > --- Uwe Freese <mail_at_uwe-freese.de> wrote: > > > The battery status (percentage) is only calculated by the voltage of > > the battery. So if it jumps up and down, the voltage of your battery > > jumped up and down. > > Maybe it would be a better idea to just give the raw voltage of the battery. > The percentage does not give a good indication of the actual time left as > this > is dependent on so many factors. I used to have a cellfone (ahem, Sagem) > that > would give the actual voltage, and that was great. I now have a Motorola and > it > says "40%" for days and then all of a sudden it conks out on me "LoBatt". > > T.J. > > __________________________________________________ > Do you Yahoo!? > New DSL Internet Access from SBC & Yahoo! > http://sbc.yahoo.com > > ________________________________________________________________________ > This email has been scanned for all viruses by the MessageLabs SkyScan > service. For more information on a proactive anti-virus service working > around the clock, around the globe, visit http://www.messagelabs.com > ________________________________________________________________________ Received on 2002-09-19 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |