So I had an extended battery on my N900 for a few weeks, but ended up going back to the stock battery because the device was a bit too bulky. However since doing this the battery reader on the N900 has been way off. It will suddenly drop from half to red and sometimes it even goes backwards (from red back up to 25%) after letting it sit for a little bit. Any ideas why this may be and how I can fix it?

~Jeff

Install pybattery, it's much more accurate than the default battery indicator.
Pybattery literally replaces the default battery icon in the status bar with it's own identical one.

and where to get it?

Yes the stock battery meter really sucks.
I have completely disabled it and im using a custom script in QBW, and am in progress off perfecting it so that i will be as close to 100% acurate to the real LiPo capacity graph from 4.23V to 3.30V.

http://talk.maemo.org/showthread.php...ight=pybattery

Given the weather we have had recently if you see the battery indicator going backwards it might be temperature related.

I was out in very cold weather (~ -15C) and the phone turned itself off, just as I was needing to make a rescue phone call.
I stuck the phone under my armpit for a while for heat and managed to turn it on and coax a phone call out of it. On returning the phone to room temperature the battery was back up to at least a quarter.

Yes the weather will have an effect on battery's. im an EV guy and this 1 day this winter i found out that i had to take the battery inside when at work because in the time at work it drained about 20% of my battery.

But the case of the battery meter in the phone, it really doesn't work very good, take it from someone that knows battery's. i only rely on the battery voltage and can see from that how much capacity that's left.


NOTE: EV is a Vespa Ciao (converted), battery is only 4KG.

The default battery meter makes a randomish guess at the state of charge when it starts (at boot), its state of charge tracking is limite by bounds set to it by the battery size indicator resistor on the battery itself. In addition to a crude integrating charge counter, it also seems to have sanity checks based on voltage, which makes it periodically re-evaluate its integrating state of charge tracking.

If the meter is only slightly wrong, it'll just stay unchanged for some time until it thinks it's correct again. If it's very far off, like after an interrupted charge or comig from cold into warm, it might actually compensate it upwards..

By the way, pybattery IS more precise, but in my experience pybattery has a significant inaccuracy that expresses itself when you're on the power kernel, at least for me. It's python so it should be fixable, but I never did take the time to make it work.

the normal battery indicator is even more corrupted on my N900 since i only charge my battery with an external charger while the battery is in the phone, my own QBW script works fine like this since it only goes by the current voltage of the battery but the standard battery meter goes nuts and doesn't update for a long time.
One thing i used to do was to launch H-E-N and close it again since it stop & starts BME, this will update the standard meter.