42toro.......ah yes, the mysterious ammeter. Yer 3rd-brush 6V-genny is rated at 11-amps. It takes about 3-amps to run yer sparkies. The 1-terminal squarecan coil needs the mandatory "infamous ballast resistor" at ALL times. The roundcan cutout disconnects the battery when you turn yer engine OFF. That way, you do NOT discharge the battery thru yer genny windings. Headlites take about 3-amps each. Add'em-up, 3 fer coil, 6 fer headlites, thats 9-amps. Wadda surprize, 2-amps charge left over.
Remember YOU are the voltage regulator. When yer NOT running with headlites, turn yer 3rd brush down so you don't OVERCHARGE yer battery and warp the lead plates and short out the battery. That means you haffta gitt down off'n yer tractor seat and walk around the tractor from side to side to do the adjust at about 1/3-throttle. That also means when you turn yer headlites ON, you gotta re-adjust yer 3rd-brush for more charge ...or... you'll have weak sparkies and DEAD battery eventually. .........the charged Dell