Small Engines (Lawn Mowers, etc.): Cub cadet, kohler engine, electrical system, ampmeter, starter generator

Question
My cub cadet 127 hydrostatic has a 12 hp kohler engine.

The engine will start with a new battery and when "jumped" and will continue to run but does not charge the battery.  Upon "jump" starting the ampmeter shows charging for a few seconds then abruptly drops to "0"..but the engine stays running.

How can I tell if have a problem with the generator/starter or voltage regulator or other part of the charging systm?

THANKS

Answer
 Hello Frank:

 1- Start the Mower. 2- With a Volt Meter, Measure the Voltage of the Battery. The Voltage should Read about 14V to 14 1/2V DC. If Not then Check the Voltage going into the Voltage Regulator. This Voltage Should be 15V up to 18V DC. If Not Then Disconnect the Wire Feeding The Regulator from the Starter/Generator. Check the Voltage again. If Voltage is not as stated above, Replace/Rebuild the Starter Generator.  If Voltage is Good, then Replace the Voltage Regulator. Hope this Helps.

 Good Luck

 Respectfully

 John