ok, you’re right, if you charge the device while on, the results are consistent, the battery indicator show a reasonable “almost full” green icon that stays there even after some time. it just need to be charged while turned on… not a big issue anyway
by the way, a question: I couldn’t monitor directly battery voltage since I have closed the DSO and don’t want to try to open it again, but is the internal oscillator amplitude related to battery voltage? it appears so to me… about 3.6-3.7 volts when operating on battery, and more when charging…