Ammeter Gauge

If you have a simple generator without voltage regulator but uses three brushes and there is only the cutout (often in a round case with only two terminals) the generator will put out a constant current so after you figure the battery is charged from starting you turn on the lights to cut back on the current that gets to the battery. 30s vintage cars and trucks used that scheme too.

If you have a voltage regulator (rectangular case with terminals for battery, armature, and field) it should be holding a constant voltage so long as the generator is turning fast enouogh and the charging current should be higher initially but should taper off. That is better for the battery. The main advantage of an alternator is that the solid state regulators commonly used hold that voltage better. There are other advantages like no back current and greater charging current at low speeds, and on MF tractors the alternator kills the tachometer.

You need to find what is drawing current when the tractor is shut down. Unhook that battery connection (the grounded one) and hook a test lamp between the battery post and the cable. It will light to indicate a leakage. The smaller the lamp, the more sensitive the test. Then unhook wiring parts until you isolate the problem. And then fix that problem and confirm the lamp stays off when you test that way.

Gerald J.

I'd look to see if you have a few dry cells, or an entirely bad battery.

JMHO, and worth all you paid for it I might add.