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

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UpInTheAir

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Jan 17, 2011
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Phuket, Thailand
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
Fuel%20Gauge%20Chip%20Reset%20-%20Android%20Terminal%20Emulator%20app.png


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.

Fuel%20Guage%20Chip%20Reset.png


Fuel%20Gauge%20Chip%20Reset%20Graph.png




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


.
 
Last edited:

staticinferno

Member
Aug 20, 2011
14
1
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
 

UpInTheAir

Account currently disabled
Jan 17, 2011
7,965
15,909
Phuket, Thailand
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

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.

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

UpInTheAir

Account currently disabled
Jan 17, 2011
7,965
15,909
Phuket, Thailand
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?

Sent from my GT-I9500 using XDA Premium 4 mobile app
 
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Djgenes

Member
Jul 11, 2013
37
2
Hi. My phone is an Xperia P. On another thread I found the following code line:


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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UpInTheAir

Account currently disabled
Jan 17, 2011
7,965
15,909
Phuket, Thailand
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.

Sent from my GT-P6800 using XDA Premium 4 mobile app
 
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norits021

Member
Jun 27, 2014
8
0
fuel gauge chip reset for note 8.0 n5100

I think I need Fuel gauge calibration or better said "reset".I own a note 8.0 n5100.do you know where the reset directory is?
I have stock Rom 4.4.2 and stock kernel as well.
 

UpInTheAir

Account currently disabled
Jan 17, 2011
7,965
15,909
Phuket, Thailand
I think I need Fuel gauge calibration or better said "reset".I own a note 8.0 n5100.do you know where the reset directory is?
I have stock Rom 4.4.2 and stock kernel as well.

No. I've never owned or used your device model.

Just search for a similar directory. It will be there. Could also try and search with root type file explorer for the file name.

Sent from my SM-T705 using XDA Premium 4 mobile app
 
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norits021

Member
Jun 27, 2014
8
0
directory listing under "sys/class/power_supply/"

No. I've never owned or used your device model.

Just search for a similar directory. It will be there. Could also try and search with root type file explorer for the file name.

Sent from my SM-T705 using XDA Premium 4 mobile app

I've searched the xda and also on internet.I didn't find the directory.
so I searched within my device.i found some directories but I didn't find the file you mentioned.
I attached my directory listing under "sys/class/power_supply/"
 

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UpInTheAir

Account currently disabled
Jan 17, 2011
7,965
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Try using the inbuilt search function of a root type file explorer. Search the whole device for the file name.

Other than that, don't know.

Sent from my SM-N9005 using XDA Premium 4 mobile app
 

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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
    Fuel%20Gauge%20Chip%20Reset%20-%20Android%20Terminal%20Emulator%20app.png


    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.

    Fuel%20Guage%20Chip%20Reset.png


    Fuel%20Gauge%20Chip%20Reset%20Graph.png




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


    .
    1

    Glad it helped :)

    Sent from my GT-P6810 using xda premium
    1
    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?

    Sent from my GT-I9500 using XDA Premium 4 mobile app
    1
    Hi. My phone is an Xperia P. On another thread I found the following code line:


    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?