On Thu, Aug 08, 2013 at 09:29:49AM +0100, Philip Ashmore wrote: > On 08/08/13 04:05, cletusjenkins wrote: > > I'm using wheezy and in gnome 3, if I disconnect my laptop from its charger > > and then at some point suspend. After bringing the system back up and > > connect the charger the battery charge indicator in gnome shows incorrect > > info. > > > > I plug in the charger and the battery charges, but it never reaches 100%, > > it stops at around usually in the 80's or 90's. The indicator shows the > > battery is charging no matter how long it is plugged in, but once the > > percentage stops increasing it will never go higher. This inaccuracy > > usually persists across reboots. I can shutdown, disconnect the charger, > > and remove the battery. The inaccuracy remains. At least once this process > > lead to a correct reading, but it hasn't worked recently. I'm not sure if > > this has gone on since I first got it or if this is a new thing. I noticed > > it about 3 months ago. > > > > This laptop is less than 6 months old, when disconnected from the charger > > the battery holds a charge for the same length it always has. > > > > Is there some file I can erase or some other procedure to reset the the > > indicator? > > > > > It's a feature of modern laptops. > > The idea is that the battery lasts longer if you avoid full > charge/discharge cycles.
Perhaps so, but if the charge isn't increasing, then that's basically "full". Batteries usually note three main values in their "fuel gagues" (a small chip in the battery): current charge, current maximum charge and designed maximum charge. The "designed maximum charge" is written at manufacture time and the "current maximum charge" is updated every so often. The ratio between current charge and current maximum charge give your your percentage full. The ratio between current maximum charge and designed maximum charge gives an indication of battery health (that is, if the battery was designed to hold 100Wh but now can only hold 20Wh, it's basically dead). Resetting the fuel gauge varies from battery to battery, but the typical way is to drain the battery (so, take the charger out and run the laptop until it shuts down. DON'T try to over-drain the battery by starting it at this point), then charge the battery to full again (plug back in, but don't start the laptop - let the battery charge at full rate until it's at 100%. You'll need to estimate how long this usually takes). The idea is that the fuel gauge monitors the increase in charge and, when the increase tapers off, that's your maximum charge. Don't try this too often, though. Deep discharges are also bad for Lithium Ion batteries. If in doubt, read the manual :)
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