Hans Kloepfer wrote:
> Thanks George.
>
> I tried some of these types of units, and I burnt them all out. I talked to another guy who had the same bad luck with these types of instruments. Unfortunately, I have to keep them installed so I don't have holes in the custom made instrument panel on my boat. This annoys me. The problem is the power supply. It works fine with a 9 volt battery, but if you want to wire it your boats house power, as in my situation, it creates a short circuit condition.
>
> Anyone else have any input on these things (shunt-wired, ebay variety LCD digital volt/amp meters). I would still like to get something in those holes that actually works.
>
> I would still like a handheld multimeter for analysis/ diagnostics that I could just clamp around a cable to check DC amperage on different legs of the electrical system on the boat. Usually these are pretty expensive. Maybe I will just have to pony up the dough for a nice Fluke or similar.
>
A 'clamp' DC ammeter is a far more complex beast than a clamp AC ammeter.
The AC ones effectively make a one turn transformer and measure the
induced voltage. This doesn't work on DC. I think they measure the
magnetic field or something like that.
It's quite common to have a DC amp function on a AC/DC clamp meter
where the only the AC amps is via the 'clamp probe'. DC current
measurements require breaking the circuit.
A too-cheap AC/DC clamp meter may only measure AC current via the
clamp. Read the specs carefully. :-)
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