XA2 power drain when turned off

General
#1

I recently went hiking for a couple of weeks, far beyond any cell service.
I turn my phone off, so there will be battery when I get out.
It was dead when I came out. I noticed it had been losing charge when I turned it on briefly (in flight mode) every few days.

Anyway, it seems the phone loses 5-10% battery capacity per day when turned off. (or in flight mode)
The battery capacity is still fine, it runs the phone for a couple of days.

Can anyone else who is not using their XA2 every day give this a try?

Is it an XA2 issue others have, an SFOS issue (seems unlikely) or is my battery just leaking power?

#2

When your device is OFF it is really OFF, so nothing in any OS can affect the battry or cause consumption.
Your battery is busted. unfortunately. :frowning:

#3

Thanks for replying.
However actually that’s not true. Set to flight mode, turn it off for 15mins. Turn it on and check the time. The clock is still running. It was powered up all the time.
It is probably inside the main SOC chip of the phone, so that was also powered up. Some/most of its internals are powered down, but that is probably done by software. Maybe/probably that is Sony firmware, but possibly it is SFOS that controls it.

Usually the hardware can power itself up fully, anytime, when off, from (at least) the clock. If it does, it relies on the OS to go back to sleep quickly with minimum power drain.

So, you cannot simply assert that it can’t draw power, because it can, and does. Hopefully not too much…

So, back to original question: Can anyone see if their xa2 loses battery charge when it is off for a day or two?
Does anyone have an XA2 opened, and can measure the off current drain.

#4

RTC is of course running, but that is a HW feature :slight_smile:

I said “…There is nothing in any OS can affect battery…”, I mean there is no difference whether you have SFOS, Andtoid, IOS or Windows running on it.

#5

Once upon a time, people rode yaks, ate turnips , the RTC was a separate IC, and there would have been a separate power control circuit. Once turned off, it was indeed a hardware function to power on.
That was then.
RTC’s are integrated into the main SOC’s. These SOC’s can have leakage and standing currents that are very high, even when powered down properly.
Powering down means software turning selected parts of the circuit off. Or not turning them off. It might be done by Sony firmware, or it might be done by Jolla software, or it might be done by a Qualcomm binary blob.
It is possible that Jolla don’t have access to a datasheet for the SOC’s as they are not manufacturers or designers of phones, and many of these have tightly secret datasheets, and apparently large parts are secret from all customers too.
As an aside, my Nokia N900 seemed to be impossible to turn off. Regardless of alarm settings the SOC periodically powered up when turned off.

Unless you know some actual facts about it, you cannot state that software can’t affect current. It can and does.

None of which helps me. I need a test of another actual phone.

2 Likes
#6

Very well put, and quite convincing arguments.
Easy to verify, too; just reimage with android and see if it has any difference in the battery discharge rate when device is switched off.

#7

Just out of curiosity I switched my XA2 off for four hours. There is no visible loss of power.

#8

With almost all electronic devices these days there is no real way to turn them ‘off’ (i.e. breaking the electrical circuit between the power supply and the device) other than unplugging them or removing the battery - and this is true of all phones, including the XA2. When you turn them ‘off’ using the power button or shutting the device down you are actually putting it into standby mode (like a TV that has been turned off with the remote control but not actually unplugged at the wall).

The ‘off’ button is a push button that makes momentary contact when you push it, it doesn’t actually electrically break any power supply circuit. So even when your phone is ‘off’ some of the electronics are still active and, at the very least, monitoring whether the power button has been pushed again to turn the device back ‘on’. As also has been mentioned, the hardware clock will also continue to run. There will therefore always be a very small and continuous power drain when the device is ‘off’ (effectively in standby mode) which will discharge the battery over time.

I have an XA2 with Sailfish on it and this will last a couple of months when shutdown before the battery is fully discharged. Given that when you turn the device back ‘on’ again the first thing that happens is that the OS boots it seems unlikely that there will be any component of Sailfish left running which could cause a significant power drain when the device has been shutdown. There will probably be some low level Sony micro-code left running, but again the power drain from this will be miniscule. If you are losing a full charge in a few days when the device is shutdown then I would either suspect a hardware issue or a battery on its way out.

There should be a significant difference between the battery drain between a shutdown device (i.e. no OS level software running at all) and a running device in flight mode (i.e. OS running but just all radio transmitter/receivers turned off). I could quite see a battery drain of between 5% and 10% per day in the latter case.

2 Likes
#9

Yes, I can. it`s the same on my 2 SFOS phones. Sometimes it happens, that a big battery drain occurs while the device is turned off by long pressing the power button to shut down the phone. Sorry, I have no idea on what this is depending.

1 Like