Battery Calibration on Droid Maxx

[1901Madison]

I have recently noticed that the battery on my Droid Maxx does not seem to be properly calibrated. For example, often times when I take it off the charger, the battery will remain on 100% for a long time. If I don't use the phone at all, it will sometimes stay at 100% for 5-6 hours. The phone barely loses any charge from 100% to 95%, but then it picks up steam and drops quickly from 95% to about 89%. Then it slows down again from say 89% to 72%. Now here is where it gets weird. Even if I don't do anything, the phone flies through the 60s. I could put the phone down at 69%, not touch it and watch a 1 hour TV show, and by the end of the show, it's at 62%. Does anyone have any clue what's going on here? I understand that the battery indicator will not always be perfectly accurate, but some of the rapid drops seem a little much.

Is there any way to recalibrate the battery to get a more consistently accurate battery indicator? Any help you can provide would be much appreciated.

 

[doogald]

It may be bad hardware. But I suppose if it were me I might do two things:

- Pick a time when it's convenient to do this and run the phone down to the point where it shuts down on its own and won't power the screen up. The plug in until the charge is reported as 100%.

- Change out the charger and cable. If you're not using the stock charger and cable, try those. If you are, try swapping them for a charger that puts out 1.2 amps (a 6W charger) and a new USB cable.

If you still see those issues, then it may be warranty replacement time. If you bought the Maxx when it first came out, you may be beyond the warranty (it came out Aug 20 2013), so, if it's out of warranty and you can live with it, then I guess live with it.

But, to answer your question, the battery pack is supposed to be always calibrating itself and resets the charging calibration when you hit full charge. There is no magic that you do to "calibrate" it beyond just using it.

 

[1901Madison]

I called Verizon customer support about the issue. They told me to reboot my phone into safe mode and charge to 100%. They said when my phone gets to 100%, I can switch it back to regular mode and let drain to 0. Then charge the phone back to 100% and it should be recalibrated.

Has anyone heard of such a method? Is it safe? I thought I remember hearing that letting a phone drain to 0 is a bad thing.

 

[doogald]

I called Verizon customer support about the issue. They told me to reboot my phone into safe mode and charge to 100%. They said when my phone gets to 100%, I can switch it back to regular mode and let drain to 0. Then charge the phone back to 100% and it should be recalibrated.

Has anyone heard of such a method? Is it safe? I thought I remember hearing that letting a phone drain to 0 is a bad thing.

It won't actually drain to zero. The phone won't allow the display to power on when it reaches a point where it's still safe to keep running. It's generally not good for the battery pack to drain to that condition every time, but once for a purpose like this will be fine.

I haven't heard of the safe mode idea, but everything else matches what I posted above, right?

 

[Rukbat]

"Battery calibration" "calibrates" the file that keeps track of which app is using what percentage of power, it has nothing to do with how fast the battery is draining. The indication - 100%, 50%, whatever - is actually a measure of the battery voltage under load - which is an approximate guess at the State of Charge of the battery. (To actually determine the SoC would have to be done chemically, and the battery would have to be taken apart - basically destroyed - to do that, so the next best thing is the terminal voltage.)

It sounds to me as if wither you have some rogue app running a lot of current out of the battery randomly or you have a defective battery.

There's no way to "calibrate" the indication against the actual SoC - we know (the industry does) the approximate curve of voltage vs. SoC, and that's hard-wired into the phone. When the voltage is X, the SoC is Y%.

"Calibration" is a waste a charge cycle. The only time you should let the battery discharge below 40% (50% is even better) is during conditioning - if the battery's been sitting in a drawer for 6 months.

Read The Care and Feeding of Lithium Polymer Batteries. (Scroll down to the Myths section if you don't want to read the rest.)