Well, the volt meter shouldn't provide any real resistance when measuring voltage - but to be honest, if you just wanted to test whether you get more power in one place than in another (rather than getting an 'absolute' measurement, measuring volts is almost certainly the easiest thing to do :)
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.
Well, the volt meter shouldn't provide any real resistance when measuring voltage - but to be honest, if you just wanted to test whether you get more power in one place than in another (rather than getting an 'absolute' measurement, measuring volts is almost certainly the easiest thing to do :)