This behavior was observed in the 7.20 software (it may exist earlier, it also certainly exists in 7.30) with the following conditions:
1. set the Edge to sleep (just a short press of the power button - as I do after a daily workout),
2. Charge them from the wall plug (I tested one from a Samsung and Sony phone, and a regular power bank),
3. Do not press the power button while charging
4. disconnect the power supply (USB)
Then the Edge 1030, if it is fully charged up to 100% - it will remain fully charged all the time. If it has been charged to a lower value - it will be increasing the battery charge indication during usage!
Normal operation of the battery indicator can be restored if any of the following events occur:
1. turn on the Edge before disconnecting power
2. restart the Edge (long press of the power button, select "power off", turn on the power)
3. charging from PC (restart occur automatically after disconnection)
This seems to be a software error: the battery charging / discharging subsystem does not change flag when the Edge is in sleep mode.
Can anyone, with Edge 1030 sw.7.30, test whether this is a general problem or maybe only my Edge does not work well?