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For tabs with battery drainage problem... or how to calibrate

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By Vlad_z, Senior Member on 12th August 2011, 06:03 PM
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I've got this problem with my tab (quick battery drainage). Symptoms would be your 100% charged tab would go down to 0% in unusual shorter time ( like 2-4 hours). You put it on charger and tab would be charged back to 100% again in substantial short time like 2-3 hours instead of 6-7 hours.

Well, after looking at this issue I think I have come up with solution.
At least, my tab looks like it's back on track... though, to say for sure I would need another couple days of testing.

The problem is not runaway wild application on a background but battery control circuit. This chip reports to OS much smaller battery capacity as it is for some reason. I will not go into details but here is what you need to try:

Flash stock kernel (may be custom kernel is not the reason for bad chip calibration and I'm 90% positive but just to be on safe side). You don't need to do factory wipe in OEM recovery for our purpose.

You also don't need to wipe batterystats.bin or use "Battery Calibration" apps from market (which does exactly the same wipe just in more end user friendly way). This wipe serves no other purpose then refreshing your usage statistics.

You also don't need to drain your battery all way down... nice, this way you don't have to wait for too long.

Well, here we go:

charge tab somewhere in between 80 and 100%.
edit: remove charger
shutdown tab (not put in hibernate/sleep) for 1 hour.
edit: turn tab on and run it for 30-40 min. or whatever it takes to drop charge to 40-50%.
shutdown tab again for 5 hours (overnight).

turn tab again and check... you should be fine now, charge it again 100% and use as usual.

That should do correct chip calibration.


PS: the reason why this chip calibration went bad at the first still remains open.



EDIT: just want to give a shortcut for those who does not feel like reading through the thread.

http://forum.xda-developers.com/show...1&postcount=41

Edit: here is calibration procedure which was modified down this thread ...

1. in CWM/recovery let it sit till battery in terminal will show less then 3700. The less you can get it the better. 3400 is probably absolute minimum.

2. shut down tab and let it sit for 1 hour.

3. plug it to charger and charge it for 5 hours.

4. disconnected charger and let it sit for 1 hour.

5. boot up your tab and test it, it your battery still not calibrated you can flash back your backup and repeat calibration procedure.

Edit: if you physically disconnect battery (you have to disassemble tablet) and keep it for couple min. that would trigger FG chip to start with default SOC curve.
Last edited by Vlad_z; 27th September 2012 at 06:15 AM. Reason: Title edit.
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13th August 2011, 06:28 AM |#2  
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Any follow up? Did this fix work for you since yesterday or anyone else?
13th August 2011, 01:33 PM |#3  
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yup, this is it...

This is how properly calibrate sg tab's batteries. There are some variations to the process but essentially battery will be calibrated in two measurements which stand apart by minimum 40% when battery is at rest on time intervals 1 and 5 hours.

No need to do factory reset, wipe batterystats, use battery calibrator apps from market or dance around with rain stick... all this will give same result as woodoo magic... though if by some reason battery calibration conditions are met then one may claim a miracle.
14th August 2011, 01:59 AM |#4  
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*sigh of relief* looks like this worked. More people that have this issue should now about this. Thank you for the fix.

Sent from my DROID2 using XDA App
14th August 2011, 07:36 AM |#5  
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Is this the same as the Sleep on Death (SOD) syndrome? that while charging it dies overnight and then you have to long press the power button and/or charge it to get it back?
14th August 2011, 07:56 AM |#6  
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Worked for me so far all good thanks

Sent from my GT-P7510 using XDA Premium App
14th August 2011, 11:02 AM |#7  
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Thanks will try this after flashing many custom roms I've been suffering from fast drainage which is not normal from when I had it on stock.
14th August 2011, 02:04 PM |#8  
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Quote:
Originally Posted by hyann

Is this the same as the Sleep on Death (SOD) syndrome? that while charging it dies overnight and then you have to long press the power button and/or charge it to get it back?

How long your tab usually works on one charge? if 8 and more hours - then no, I would think that there is a bug in Android charger control.
14th August 2011, 04:07 PM |#9  
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Quote:
Originally Posted by Vlad_z

yup, this is it...

This is how properly calibrate sg tab's batteries. There are some variations to the process but essentially battery will be calibrated in two measurements which stand apart by minimum 40% when battery is at rest on time intervals 1 and 5 hours.

No need to do factory reset, wipe batterystats, use battery calibrator apps from market or dance around with rain stick... all this will give same result as woodoo magic... though if by some reason battery calibration conditions are met then one may claim a miracle.

May I ask what do you mean by rest time intervals of 1 and 5 hours?

Does it mean that the calibration will only take place when the tab is off for 1 hour, then switch on and used till battery depleted by a further 40% minimum and the switch off for another 5 hour. Correct?

Also , is this 40% refer to value before or after calibration? I asked this because when I restart my tab the value changed (ex: 36% before restart to 53% after restart)
Last edited by wlighter; 14th August 2011 at 04:23 PM.
14th August 2011, 08:32 PM |#10  
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Quote:
Originally Posted by wlighter

May I ask what do you mean by rest time intervals of 1 and 5 hours?

Does it mean that the calibration will only take place when the tab is off for 1 hour, then switch on and used till battery depleted by a further 40% minimum and the switch off for another 5 hour. Correct?

Also , is this 40% refer to value before or after calibration? I asked this because when I restart my tab the value changed (ex: 36% before restart to 53% after restart)

Yes that's correct.

Fuel gauge chip will take 1 measurement of open circuit voltage and internal resistance only when battery is at rest (no charge/discharge) for at least 40min. - so I say 1 hour just to be sure...

Consecutive measurements, from which gauge chip can derive capacity of the battery have to be at least 40% and 5 hours apart.

Technically speaking, that 40% difference can be in either directions. Say you have 40% as of now, leave it in rest for 1 hour, then charge it to 100% and leave it at rest for 5 hours and you will have same result.

Condition "at rest" means voltage change less then 4mV (or mkV) per sec. - I don't remember.

When tablet is in sleep some background processes may awake tablet briefly and reset the 1 hour counter - so to make it work for sure, simply do shutdown.

if you want additional reading on my findings then look here:

http://forum.xda-developers.com/show...&postcount=517
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14th August 2011, 11:21 PM |#11  
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I tried this method...

1.Charged tab t0 80%, then shut down (removed charger) for 1 hour.
2.Turned on tab and played games for about 45min till battery was 49%.
3.Turned off tab and let sleep for 5 hours (charger still removed).
4.Turned tab back on and battery reads 79%, used for about 20min and battery reads 68%... Seems battery drain is still happening?

Right now i'm charging the tablet back upto 100% then perhaps try this method again... Did I do something wrong?

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