wa8yxm wrote:
IF the Go Power said 13.6 and the meter 18.. I am guessing the meter had a problem. Perhaps it was set on AC not DC (THe relationship is the square root of 2 or about 1.414 right about the error you saw) But I'd have to think some to figure out which way is which.
Peak voltage on a a 12 volt RMS is just shy of 18 volts.
Most meters that aren't true RMS meters measure average voltage on AC mode and scale the reading to display RMS voltage for a sine wave. Peak responding meters are pretty rare and are not be very useful if there's some superficial noise on an AC line (they'd read the spikes rather than the line voltage).
I suspect most ignore DC in AC mode, though perhaps not all. Based on a quick test, my meter does.
At any rate, a meter that is peak responding and senses DC in AC mode would read too low, since it needs to scale the actual peak voltage down to get the equivalent RMS value.
