I have a rooted Galaxy Nexus (maguro) runnung an AOSP 4.4.4 rom and Franko.Kernel r396. I also have Gravity Box installed and have replaced the battery percent icon with the circle battery. As far as I can tell, these are the important factors relating to my issue. I have an app that shows battery voltage next to percent, and at 50% the voltage is 3600, but from what I've seen 3600 is supposed to be zero. If my battery falls below 50%, I have to keep my screen off or the phone dies instantly with no warning.

1 Answer 1


Let me simplify since I see we have debaters.

You should calibrate your battery:

After you use your battery, as low as it will go, below 20%. Plug it into A/C Power until it is definitely fully charged. Wait an extra 20 minutes to make sure that it is fully charged. Then you need to:

1) Remove the battery stats file: rm /data/system/batterystats.bin

This will prevent you from seeing any discrepancies in the usage of your battery & the battery stats.

2) Wipe the dalvik cache: rm /data/dalvik-cache/*

You stated that an app is showing your voltage levels as being correct, so you may need the app's cache cleared.

3) Then Reboot: reboot

This is what causes the kernel to re-calibrate your battery, when the phone is rebooted after a full charge.

  • 1
    Can you cite the reason for this extra waiting for 20 minutes (would 0<X<20 or 20<X<(20-30) work as well)? That would be very helpful here. :-)
    – Firelord
    Commented May 8, 2015 at 6:33
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    Thank you for that comment. I added a bit more why I do that, and why 20 minutes. Over should be fine. Possibly less, but as I stated, the script that I have always waits 20 minutes when set to auto. I wish I had a more technical reason for the time, but that is it. The truth. :)
    – SudoSURoot
    Commented May 8, 2015 at 6:45
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    Removing the batterystats.bin is not related at all (yeah, the good old calibration myth). That file just holds statistics on how apps were using the battery – not how the battery was depleted. Secondly: could you please explain what the Dalvik cache should have to do with it – and if it really is related (which I doubt), what would be the equivalent with ART (Android 5+)? Third: For a calibration, the battery must be "depleted" first (discharged to ~5..10%), as otherwise there won't be a complete charging cycle.
    – Izzy
    Commented May 8, 2015 at 8:57
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    References: Start with our calibration tag-wiki and especially our battery tag-wiki and follow up their links. Reference concerning batterystats.bin: find it explained by Google developer Dianne Hackborne :)
    – Izzy
    Commented May 8, 2015 at 9:02
  • I added more info for you. I know the batterystats.bin file removal does not calibrate your battery. That is why I had more than just that listed. As you can see it is the act of rebooting when the device is fully charged that will re-calibrate it after being below 20%.
    – SudoSURoot
    Commented May 10, 2015 at 1:08

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