That's the sort of thing I was expecting based on your previous message. @Gordon or one of the other hardware experts might be able to have a guess based on that what the cause is. My idea as to the solution, but someone else might have a better idea, would be writing the max and min voltage to storage and reading the value on boot. Max is easy, whereas Min would probably take a few cycles to get accurate.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
That's the sort of thing I was expecting based on your previous message. @Gordon or one of the other hardware experts might be able to have a guess based on that what the cause is. My idea as to the solution, but someone else might have a better idea, would be writing the max and min voltage to storage and reading the value on boot. Max is easy, whereas Min would probably take a few cycles to get accurate.