The old style zero center ammeters are not very desirable in my
opinion unless mounted very close to your batteries, or it has an
external shunt. Without a shunt it is necessary to run a high current
wire (large) all the way to the meter and back to your battery/engine
area. Better to get one of the new digital ammeters (with shunt) that
reads both positive and negative flow.

Correct me if I'm wrong (not being an electrical type But aren't
external shunt type amp meters milli-volt meters and the meter simply
measures the voltage drop across the shunt??

I don't see that the voltage could be reversed to operate the meter on
either side of zero.

I always assumed that this was the reason you we never see any external
shunt type 'zero center' amp meters.

If anyone knows of a 150-0-150 amp, shunt type amp meter, I would like to
know where I can get one. I could then monitor my house bank charge and
useage at the DC panel without opening the inverter/charger locker.

(Sorry, I didn't mean to 'hijack' this thread. This topic may deserves it's
own thread.)

Steve
s/v Good Intentions