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Illinois, an "Ideal Ammeter" is electrically a zero ohms short circuit, but of course, none are ideal. If its wired correct BOTH the Supply and Load terminals MUST read hot battery voltage. The Supply side usually has but one wire and thats the hot ungrounded battery feed source, often conected at the starter or solenoid where the big battery cable attaches. The other Load terminal is what feeds loads like lights n ignition PLUS the BAT terminal on a Voltage Regulator or Cutout Relay. If its mis wired it may not be correctly reading the current flowing into (charging) or out of (discharging) the battery. With the tractor NOT running if you switch on the ignition (if a coil ignition not a mag) if working n wired correct it should swing to discharge (around - 4 amps) and then if you also turn on the lights it should swing further to discharge DOES YOURS????? ? An accurate DC voltmeter on the battery not running, if its full charged, should be around 12.6 volts, but If running and charging well around 13 to 14 or so volts EVEN IF THE AMMETER WERE NOT WORKING. Disconnect everything n insure theres near zero ohms through the ammeter and then with all attached insure theres hot battery voltage on BOTH sides. Typical charge current may be 10 to 20 amps, less typical loads like ignition n lights 4 to 10 amps, so what max scale is your ammeter????? Perhaps the movement is simply stuck?? Does the needle ever deflect any if its lightly tapped?? Post back your findings n any questions n we will try n get her working, Check wiring n voltages and resistance !!!!! !!!! Let us all know, good luck n God Bless John T in Indiana, retired electrical engineer
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