How to re-calibrate battery?

Winston P

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Dec 12, 2014
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There is a secret code in the dialer, *#0228#, that resets the battery callibration completely, killing the phone straight to 0% and asking you to charge to full. I last used it on my S4 and went from 2h SOT to 4.5h SOT, but it also completely screwed up the battery callibration, which meant the phone would go down quickly in charge, but "self charge" and recover in standby. It meant, e.g. used from 75% to 65% in about 15 minutes, which is a discharge rate of 1.5 minute per %, but then recover 5% if I leave it for a while, which would make the discharge rate an actual 3+ minutes per %. Is there any way to get the benefits of battery reset without this?
 

Rukbat

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Feb 12, 2012
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"Battery reset" has nothing to do with the battery.

There are two ways to tell the State of Charge - chemically measure the electrolyte (more expensive for the equipment than the entire phone) or measure the terminal voltage and refer to a chart of voltage vs. SoC. The second one is the one used in cellphones.

To "recalibrate" is merely to reset the chart "100%" point to the voltage coming from the battery when it's fully charged. We do this by charging and watching the battery voltage until it stops going up, then telling the app we're using for this |reset|, at which point, it rewrites the "calibration" file with the immediate voltage at the time you told it to reset. Percentages of voltage below that tell the phone what percentage of charge is left.

The file in which that information is kept is a system file, so the phone has to be rooted. The app I use (there may be others) is Battery Calibration.

Discharging the battery to 0 is not only no longer required (it used to be required to run the phone until it shut off) to "format" the battery, it's strongly recommended hat you never allow the charge to get below 40%. Doing so only shortens the life of the battery.

*#0228# gives you the battery statistics, it doesn't do anything to the calibration. (And it's not universal - the only phones I can confirm it working on are Samsungs. (I can also confirm that it doesn't work on Pixels.)

Also, "recalibrating the battery" doesn't do a thing for the battery life or time between charges, it just makes the percentage reading more accurate. It's "battery percentage reading calibration", it doesn't "recalibrate the battery" (not that that phrase actually means something - batteries, any kind of batteries, never need to be "calibrated".)
 

Winston P

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Dec 12, 2014
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"Battery reset" has nothing to do with the battery.

There are two ways to tell the State of Charge - chemically measure the electrolyte (more expensive for the equipment than the entire phone) or measure the terminal voltage and refer to a chart of voltage vs. SoC. The second one is the one used in cellphones.

To "recalibrate" is merely to reset the chart "100%" point to the voltage coming from the battery when it's fully charged. We do this by charging and watching the battery voltage until it stops going up, then telling the app we're using for this |reset|, at which point, it rewrites the "calibration" file with the immediate voltage at the time you told it to reset. Percentages of voltage below that tell the phone what percentage of charge is left.

The file in which that information is kept is a system file, so the phone has to be rooted. The app I use (there may be others) is Battery Calibration.

Discharging the battery to 0 is not only no longer required (it used to be required to run the phone until it shut off) to "format" the battery, it's strongly recommended hat you never allow the charge to get below 40%. Doing so only shortens the life of the battery.

*#0228# gives you the battery statistics, it doesn't do anything to the calibration. (And it's not universal - the only phones I can confirm it working on are Samsungs. (I can also confirm that it doesn't work on Pixels.)

Also, "recalibrating the battery" doesn't do a thing for the battery life or time between charges, it just makes the percentage reading more accurate. It's "battery percentage reading calibration", it doesn't "recalibrate the battery" (not that that phrase actually means something - batteries, any kind of batteries, never need to be "calibrated".)

I understand that the menu is exclusive to Samsung, but if you press quick start at the bottom, your battery goes straight to 0%. At least the indicator does. And while I can't tell you WHY I went from 2h SOT on my S4 to 4h SOT after doing that, I can tell you it happened.
 

methodman89

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Feb 5, 2018
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I understand that the menu is exclusive to Samsung, but if you press quick start at the bottom, your battery goes straight to 0%. At least the indicator does. And while I can't tell you WHY I went from 2h SOT on my S4 to 4h SOT after doing that, I can tell you it happened.
That is an impressive jump in sot. Did you also reboot the phone or change anything else? Screen brightness dimming , shutting off GPS and wifi when not needed could also add a couple of hours.
 

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