[patrickt]

The voltmeter versus ammeter debate has been around forever and hashed out here many times. The main drawback to an ammeter is the safety aspect. A good shunt wire will take care of that and there are aspects of an ammeter that are desirable if you know what you're looking at. My ammeter tells me a ton of information, but only because I've been watching it for almost 20 years under a variety of conditions. That said, there are still times that I'd like to know what my voltage is without having to hop out of the car and hook up a VOM under the hood. That's when I plug in my little cigarette lighter voltmeter that also happens to have two USB outlets in it as well, just in case I need to charge my phone (which has never actually happened, but could). The combination of having an ammeter and a voltmeter together can't be beat when you're trying to diagnose an electrical problem -- real or perceived. But for 99% of the time, I run an ammeter alone.