M 12 volt conversion

The ammeters SUPPLY side terminal has but ONE WIRE and thats to the hot ungrounded battery post often via a connection to where the big battery cable attaches to the starter switch or solenoid

The ammeters other LOAD side terminal is what wires to the alternators output PLUS feeds alllll loads like lights n ignition often via a wire from the ammeters Load terminal to the BAT input terminals on those switches.

If its wired correct if you turn the lights or ignition on engine NOT running the ammeter should swing over to - discharge but then when running if shes wired right and the alternator works, it should swing over to + charge IF IT DOES JUST THE OPPOSITE OF THAT SIMPLY SWAP LEADS

If a voltmeter is placed on the battery engine not running if good n charged it ought to read around 12.6 volts, but then when running fast if shes charging it ought to rise to the 13 and 14 and a lil over range.

Ought to be a piece of cake

Best wishes n God Bless

John T

Wire to starter switch (battery side) ALONE on one side of ammeter. JUST THE ONE WIRE ON THAT POST.

Wire from alternator, and ALL electrical loads to the other post of the ammeter.

Then, you need to watch the battery VOLTAGE.

If it is over 15.5 Volts, you have a regulator problem.

If it is low (less than 14.5 Volts, or so), and the alternator is still charging heavily, it points to a bad battery (shorted cell).

Also, you say "it goes to full charge"... is that on an original 15-0-15 or 20-0-20 Amp ammeter, or a replacement 60-0-60 Amp ammeter?

If it reads backwards (CHARGE with the engine not running), simply swap the wires between the two ammeter posts.

Verify that the alternator is doing it's job by checking the voltage at the battery after it has run and charged a while. You are looking for 14.5 to 15.5 Volts.