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[TWEAK] SGT 7.7 Battery Calibration [Fuel Gauge Reset]

OP UpInTheAir

9th August 2013, 03:40 AM   |  #1  
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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........


DISCLAIMER : 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 !


REQUIREMENTS :

1. SGT 7.7
2. Rooted firmware and SuperSU / Superuser app installed
3. Android Terminal Emulator app installed & granted SU access
4. Existing directory : /sys/class/power_supply/battery/fg_reset_cap


FUEL GAUGE CHIP RESET & BATTERY % "REPORTING" CALIBRATION

Method :

1. Open Android Terminal Emulator app
2. Type & enter
Code:
su
echo "1" > /sys/class/power_supply/battery/fg_reset_cap


3. Reboot device
4. Battery % "reporting" calibration (digital)
a) Deplete battery to 5-10% (NOT ZERO)
b) Charge UNINTERUPTED until FULL (don't touch)
c) Unplug and then use normally. Device should then re-calibrate itself
5. 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 available mV.







This obviously worked for me, no promises, but hopefully it helps some of you too. :thumbup:


.
Last edited by UpInTheAir; 23rd August 2013 at 03:10 AM. Reason: added info
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31st August 2013, 03:01 AM   |  #2  
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Good stuff
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31st August 2013, 04:08 AM   |  #3  
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Quote:
Originally Posted by ZhenMing

Good stuff

Glad it helped

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21st September 2013, 12:24 AM   |  #4  
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May have to try this. I have noticed that I'm starting to see this more in my tab but I haven't flashed or kernel'd near that many times. I have been running cm9 for over a year now. I have been using the nema battery calibrate tool though.

It's good to know there is another step to try, I was about ready to order tools and an OEM battery and make a swap.

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21st September 2013, 12:49 AM   |  #5  
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Quote:
Originally Posted by staticinferno

May have to try this. I have noticed that I'm starting to see this more in my tab but I haven't flashed or kernel'd near that many times. I have been running cm9 for over a year now. I have been using the nema battery calibrate tool though.

It's good to know there is another step to try, I was about ready to order tools and an OEM battery and make a swap.

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If your circumstances warrant it, yeah, give it a try.

Forget the app though (edit: are useless for our device), just follow the steps and hopefully you'll see a difference.

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Last edited by UpInTheAir; 21st September 2013 at 01:33 AM.
30th September 2013, 01:26 AM   |  #6  
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Quote:
Originally Posted by staticinferno

May have to try this. I have noticed that I'm starting to see this more in my tab but I haven't flashed or kernel'd near that many times. I have been running cm9 for over a year now. I have been using the nema battery calibrate tool though.

It's good to know there is another step to try, I was about ready to order tools and an OEM battery and make a swap.

Sent from my GT-P6810 using XDA Premium 4 mobile app

So how did you get on?

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26th December 2013, 01:42 AM   |  #7  
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great work
13th February 2014, 06:00 PM   |  #8  
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Hi. My phone is an Xperia P. On another thread I found the following code line:


Quote:

Knowing this the command line that "should" reset the chip is:

Code:
echo "1" /sys/class/power_supply/ab8500_fg


As you can see, without the > sign. and showing a different path. I wanted to know exactly how to perform it.
Could anyone help me, please?
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14th February 2014, 06:22 AM   |  #9  
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Quote:
Originally Posted by Djgenes

Hi. My phone is an Xperia P. On another thread I found the following code line:





As you can see, without the > sign. and showing a different path. I wanted to know exactly how to perform it.
Could anyone help me, please?

As Post #1 states, you need to check your device has the directory/file you want to write to. Use a root type file explorer for that. I can't comment on your device, because this guide is for a SGT-7.7, but suggest to use the same format and method as in the guide. As always, nandroid first.

Best of luck.

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17th February 2014, 05:53 AM   |  #10  
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Great Tips
Very Helpfull, my battery tab need to calibrate

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battery cal, fuel gauge reset, samsung galaxy tab battery cal, sgt 7.7 battery calibration
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