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[bug] Low battery notifications wake up the display

asked 2016-08-23 18:13:01 +0200

nthn gravatar image

updated 2017-06-14 10:41:38 +0200

Probably caused by the same as this, but this one makes no sense at all. If the battery is low, it really makes no sense to turn on the screen on to notify that the battery is running low. Turning on the screen will consume more battery power, which in turn generates low battery notifications more quickly, which then turn on the screen again and again, and the battery ends up running out a lot faster than it should. On top of the unnecessary power consumption, it's also simply very annoying.

Update: this is still an issue on 2.1, and there is no longer an option in the Settings to disable notifications when the screen is locked, meaning there is no longer any workaround. My bad, it's still there, under 'Device lock'.

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A rapidly blinking LED instead?

vattuvarg ( 2016-08-23 20:54:54 +0200 )edit

The previous behaviour was just to vibrate (which was already annoying in itself because from 10-0 it generates about 30 notifications, so 30 vibrations) and if the screen was already on, show a notification about the low battery level, but not explicitly turn on the screen to show the battery is low.

nthn ( 2016-08-23 22:33:06 +0200 )edit

i have the same issue, should just have an LED pattern and light for it, i would say a slow blinking red light would be good and an occasional vibrate say every 20min.

DarkTuring ( 2016-11-08 17:26:30 +0200 )edit

In addition alerts "Unplug charger from USB to save energy" is not needed at all. When the phone is on the charger power should be used from the charger period. The reason is that it wouldnt use your battery, also in a car setup you might want the screen always on and want it to last 4hours on your road trip, so there are reasons to permanently connect it even on 100% battery power.

DarkTuring ( 2016-11-16 18:43:23 +0200 )edit

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answered 2016-11-09 14:47:02 +0200

spiiroin gravatar image

updated 2016-11-09 14:48:20 +0200

Note that constant trickle easily adds up and consumes more power than short lived high activity.

Really rough ballpark estimate with off my hat Jolla1 values, assuming 5 hours for the final 10% drop:

  1. Do bells and whistles at each % drop: 500mA * 5s * 10 -> 25 As
  2. Static led pattern: 15mA * 5h -> 270 As
  3. Breathing led pattern: 30mA * 5h -> 540 As

So from PM point of view the display wakeup [some fraction of that (1) case] does not really matter that much, and using led would not be any kind of improvement.

From UX pov the situation is different and design/ui teams have been tweaking the notifications in the resent past but I do not recall all the details of those changes.

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@spiiron as far as i know the LCD and CPU are the main power draws on a phone, these power draws should be limited, A scale dowb CPU, suspend processes, B dim display and not use it.

For the LEDs once below say 10% battery you can modulate them to prevent the power draw you are indicating.

DarkTuring ( 2016-11-16 19:05:52 +0200 )edit

@DarkTuring I'll try to rephrase: The way it works now has the device using lowest possible amount of power for ~99.7% of time (50 s / 5 h). If we use led, it will be using more than lowest possible amount of power 100% of the time (5 h / 5 h). Even if we would altogether disable all audible and visual cues used atm, it would still leave only 1mA or so to burn in the LED.

So what I'm trying to say is: Showing the notification is not some huge power drain -> using huge power drain as rationale for changing how it works is moot. However that does not mean it could not be changed due to UX reasons, say "I do not like that display comes up" or "I'd refer led over notification".

spiiroin ( 2016-11-17 18:26:20 +0200 )edit
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Asked: 2016-08-23 18:13:01 +0200

Seen: 541 times

Last updated: Jun 14 '17