Is there a trick to taking (car running) voltage measurement at the battery? I got wild numbers, up to 375vdc and then several times got 20-ishvdc. Expected maybe 16vdc.
Battery is constantly low, want to rule out the alternator.
Those are indeed crazy readings.
I would measure between the positive battery terminal to a solid ground, such as the frame.
Even 20 volts would be way too high (assuming a 12 volt system) and 375 would be deadly.
Are you sure you are reading DC volts set to the correct voltage range?
@ceorl thanks, yes to multimeter setting, and indeed readings vary a lot whether probes are on wires, clamps, terminal. I'll try just as you say.
@ceorl steady 13.9vdc
That is perfect! ;)