Do you have an example of the readings you're getting? I just checked and it should definitely just return the battery voltage in volts.
@Gordon started
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.
Do you have an example of the readings you're getting? I just checked and it should definitely just return the battery voltage in volts.