[Renate]

It's hard to say. Battery state of charge statistic can be kind of flakey. Under the same load (on and idle) and temperature the battery voltage should be enough to tell you how it's doing.

How to tell if your device is really sleeping and doesn't have a wake lock can be tricky. The best way is if you have a direct external measurement of the battery current. If the battery connector is a nice big 2-4 pin connector that's easy. If it's a teensy-tiny "mezzanine" connector it's difficult.