Bruce in Alaska writes

What you need to do is put a 100 Amp Shunt in series with the main
battery connection and then buy an appropriatly scaled Center Zero
Meter to connect to the shunt. Paul Hendricks at Hendricks Electric
at Fisherman's Terminal can set you up with this stuff.

For testing purposes you can use the batteries earth lead as a shunt,
and calibrate it with a known load, like a 4 amp nav light. A stout lead
is gonna be in the region of 5-10mV/100A, so you'd need a reasonable
Multimeter.

--
Trevor Dennis
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