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Is it possible to calibrate the battery voltage measurement?

asked 2014-12-05 12:21:13 +0300

Jolly-Jo gravatar image

Sometimes the battery appears to be discharging rapidly, sometimes slowly. After rapidly discharging, sometimes the battery display even goes up again by 1% or so. I don't suspect any permanent battery drainage or hw problem, so I was wondering if it is possible to calibrate the voltage measurement.

In the thread https://together.jolla.com/question/8562/battery-issue/ it is suggested to discharge the battery totally, then charge it while the phone is still switched off. Will this cause any calibration to occur? Does SW adjust its knowledge of lowest / highest possible voltages whenever an out-of-range voltage is seen? Why does the phone need to be switched off when charging?

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just so you know, the % (capacity left) indicator is not a voltage measurement.

urjaman ( 2014-12-05 12:40:25 +0300 )edit

Well, even if the percentage does not tell the voltage as such, I suspect the indicator is calculated from a voltage (and potentially current) measurement. Please let us know if you have information that this is done in a different way.

Jolly-Jo ( 2014-12-05 13:30:15 +0300 )edit

Update: I've not seen the battery display go up just like that in a very long time. Sometimes the value jumps after a reboot, a few times even by more than 5 % (both up and down).

But another peculiar part is that the percentage points charged from a PC's usb don't seem to last as long as the percentage points from the wall plug. I.e. the battery percentage seems to go down a lot faster after charging from a PC compared to charging with the plug charger. This cannot be seen always, but quite often, e.g. after I have used the debug network interface via usb. I have performed the discharge-completely-then-charge-while-switched-off-trick in the mean time, but still see this issue.

So while my observations are a bit different nowadays, it'd still be nice to get some light into this matter.

Jolly-Jo ( 2015-01-20 14:54:52 +0300 )edit

Update2: I noticed that the percentage gets mixed up basically always after rebooting using SailfishReboot. It usually shows something close to 100% after a reboot, no matter what the real situation is. When switching the phone off and on again, the 'real' percentage returns.

Jolly-Jo ( 2015-01-23 22:22:19 +0300 )edit

Same question for me. Battery level display is totally weird after replacing the original (dead) one. Connected to the wall plug it rarely reaches 100%, instead goes to some value (e.g. 76%) and than decreases while plugged in. Sometimes it does not go beyond 40%, but sometimes 100%. Loading time does not mater. Wall plug or PC cable is just the same. I see spontaneous reboots at various battery levels, sometimes multiple cycles. To stop that, I take out the bat, wait a while and start up, facing a percentage that has nothing to do with the pre-shutdown value. Clarification of any kind would be great. (Well, if there would be a suitable replacement phone available I'd drop the J1 immediately (since there is no original replacement akku avail, presumably). This battery thing is driving me nuts. But no chance to find a non-Android/iOS phone that's not too large...)

meriones ( 2019-08-14 10:38:56 +0300 )edit

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answered 2015-01-06 11:31:50 +0300

pichlo gravatar image

+1 to a request for an official statement on a battery calibration.

I woke up this morning and the battery gauge said 32%. I started a browser and the phone rebooted. When it was just about to show the desktop, it rebooted again, ad infinitum. It stayed in this loop for about two minutes or so until I found and plugged in the charger, then it booted properly. Showing 16% battery level.

I had to take it off the charger and go to work. Battery level was back to 30%. Opening an email got it into a new boot loop. Luckily I keep a spare charger at work.

This is the first time I have seen this behaviour on my Jolla. Just a few days ago my battery went down to 2% without a problem before I plugged in the charger. The last time I have seen a similar behaviour was on a phone whose battery was 6 years old. Mine is about 1 year old.

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I should add to the above that following the calibration method linked in the questionhad worked for me, at least for now. Still, an official statement on the topic would be nice ;)

pichlo ( 2015-01-13 14:02:35 +0300 )edit

Thanks for your comment, good to know that it actually works. I started to suspect already that it's one of those circle-your-house-naked-at-full-moon-type of advice :-)

Jolly-Jo ( 2015-01-13 16:14:01 +0300 )edit
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Asked: 2014-12-05 12:21:13 +0300

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Last updated: Jan 06 '15