[TWEAK] SGT 7.7 Battery Calibration [Fuel Gauge Reset]
Samsung Galaxy Tab 7.7 Battery Calibration [Fuel Gauge Reset]
If you are having incorrect battery SCALING issues, this will reset your device battery % to scale correctly to the available mV.
After flashing kernels and ROMs 100's (possibly 1000) of times on this device, I had an issue where my tab would not display 'actual/real' battery percentage correctly.
My tab would discharge to approx 30-35% then drop to around 10-11% almost instantaneously, sometimes shutting off if I wasn't paying close attention !
Similar to the SGS2, resetting battery stats doesn't work and nothing to do with it anyway, it just resets the reporting in device settings/battery. Battery % reporting calibration didn't help either.
There are apps available for SGS2 to reset the fuel gauge, but don't actually work for our device because of the file name & location is different. Also, the SGS2 has the advantage of being able to remove the battery (easily) and leaving out for approx 180 sec, apparently giving the same affect of reset.
I got he idea from this thread : Questions about "Fuel-Gauge chip" and how it works
& recognised developer entropy512. After some digging during my SkyHigh kernel development, I found the correct directory for my device and gave it a try........
: The below reset method has been successfully tested on my P6810 ICS 4.0.4 running SkyHigh kernel ! MAY NOT WORK FOR YOU, so NANDROID first
. SGT 7.7
. Rooted firmware and SuperSU / Superuser app installed
. Android Terminal Emulator app
installed & granted SU access
. Existing directory : /sys/class/power_supply/battery/fg_reset_cap
FUEL GAUGE CHIP RESET & BATTERY % "REPORTING" CALIBRATION
. Open Android Terminal Emulator app
. Type & enter
echo "1" > /sys/class/power_supply/battery/fg_reset_cap
. Reboot device
. Battery % "reporting" calibration (digital)
a) Deplete battery to 5-10% (NOT ZERO)5
b) Charge UNINTERUPTED until FULL (don't touch)
c) Unplug and then use normally. Device should then re-calibrate itself
. Repeat Step 4
(ONLY IF NEEDED)
RESEARCH NOTES & RECOMMENDATIONS
* Carry out Step 4 once
in every 30 charge cycles to keep Battery % "reporting" (digital) calibrated
* Continual deep discharge will shorten battery life
* Don't let the battery discharge completely : potential to damage the battery and/or the battery fall "asleep" (internal safety circuit opens) with the charger then unable to service the battery.
Screenshots below after fuel gauge reset. You can see the immediate drop from 87 -> 70% to align correctly with the approx
This obviously worked for me
, no promises, but hopefully it helps some of you too. :thumbup: