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Battery drain in Flight mode with no apps running

asked 2019-04-10 14:25:50 +0300

JooJ gravatar image

updated 2019-05-06 17:42:30 +0300

jovirkku gravatar image

[Updated 2019-04-17 to mention new observed behaviour when Flight mode is turned off.]


Device drains battery in Flight mode with no apps running. The drain rate is approx. 3%/h, which is about 10x higher than an idle device with 4G, or 100x higher than a rebooted, idle device. The high rate is sustained over many hours.

This has killed my device during night several times. Apart from the obvious maltreatment of the battery, it is also a major usability issue for me, because I can't trust alarms to fire in the morning.


It seems a reboot fixes the issue, but turning Flight mode off then on does not (at least not reliably so). Update: I have now seen the problem go away after turning Flight mode off. The previously observed behaviour was that drain would drop when turning Flight mode off, then go up when turning it on again.


This happens 1-3 days after recharge + reboot, with light use of the device. Exact conditions unclear. It could be happening when device has been on for a certain time, or there's some background task that handles Flight mode incorrectly. Is there a race condition somewhere in background activity in Accounts?

  • Like if Flight mode gets turned on between software checking for network availability and starting communication on the network?

  • Like software retrying communication after a network timeout/error without first checking that the network is still available?

Device and OS version

Running Sailfish X on an Xperia X, single-SIM model. Same behaviour observed at least in the previous version of the OS.

Accounts/background activity

One email account, polled every 30 min. One CalDAV account, set to manual updates.

Apps used

Calendar, Clock, Email, Settings. Issue appears despite all apps being closed.

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Do you know the app Lighthouse from jolla store? It shows the cpu need of every running process. Maybe it will help to find the reason of your drain

dirksche ( 2019-04-10 18:54:30 +0300 )edit

You can use a process monitor like Lighthouse or Crest to check which processes are using more CPU during the fast drain period.

addydon ( 2019-04-10 18:56:20 +0300 )edit

Good advice, I'll install Lighthouse and see what that clues I can get from it.

JooJ ( 2019-04-10 19:25:07 +0300 )edit

Sounds like your phone is not entering cpu sleep mode. Happens to my Xperia X ocassionally as well, you can install System monitor to check it.

till ( 2019-04-10 20:30:12 +0300 )edit

CSDTool also has a section for monitoring 'Power consumers', like WLAN, GPS, Brightness, etc

Edz ( 2019-04-11 11:46:05 +0300 )edit

3 Answers

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answered 2019-04-17 12:53:27 +0300

JooJ gravatar image

updated 2019-04-17 12:55:01 +0300

Not really an answer, but some findings I'd like to share. SystemDataScope has some interesting and detailed graphs, and I happened to "strike gold" this time :( The battery drain during Flight mode was far worse than I have seen before, and the device became hot.

image description

Above, you can see how lack of CPU sleep, dominating C1 idle state, and high fork rate all coincide with high battery drain. (I have combined several graphs into one.) Then have a look at my manually logged battery charge and Flight mode setting: image description

The time scale is not aligned with the one from SystemDataScope, but the interval with high battery drain is clearly visible. The horizontal, grey line shows when Flight mode was turned on. As you can see, the high drain incident happens when Flight mode is turned on, then disappears when it is turned off again.

The device was not entirely idle during this test, I had Calendar, Jolla Store, Email and SystemDataScope running. SystemDataScope and its data collection daemon seem to require very little power, which is different from Lighthouse.

Anyone with an idea about what to try next?

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answered 2019-04-17 13:02:59 +0300

Robberey gravatar image

Do you have Android support running? You got to kill that of after every use. At least on my Xperia XA2 Dual SIM that seemed to be the main reason for heavy battery drain.

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No, I had no Android apps started since reboot and Android support set to not auto-start on boot.

Have you seen Android apps/support go crazy when in Flight mode?

JooJ ( 2019-04-17 13:35:03 +0300 )edit

can' t say, as I don't use flightmode. I will try, maybe.

Robberey ( 2019-04-17 16:05:02 +0300 )edit

answered 2019-05-06 17:12:23 +0300

JooJ gravatar image

I've now tried different things and observed battery drain, sleep mode and idle states i SystemDataScope. The situation improves after doing the following:

  1. Rebooting stops severe battery drain
  2. Disabling email poll seems to make severe drain occur much less often
  3. Toggling Flight mode on/off repeatedly sometimes seems to stop severe drain. It's a procedure over several minutes, though. (There's a clear connection between Flight mode being enabled and the device being very busy, until finally the device comes to rest even in Flight mode.)
  4. Charging sometimes seems to stop severe drain

Manually syncing calendars still seems to sometimes cause high drain if enabling Flight mode after sync has completed.

I have also seen the device go crazy during charge, no sleep and very busy CPUs, leading to hot device and slow charge. Things have returned to normal as soon as I disconnected the charger.

So, I have sort of a work-around, even if it's pretty tedious, and I'm very pleased with battery life if/when things work. Reliability is still an issue and there's clearly something wrong below the user interface. My gut feeling says it is a race condition, but who knows?

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Asked: 2019-04-10 14:25:50 +0300

Seen: 879 times

Last updated: May 06