1973 Gravely 812 charging system problems

Mike Lambert

New User
My 1973 Gravely 812 garden tractor, with a 12 horsepower Kohler engine, doesn't seem to be charging the battery. Can anyone please help me with troubleshooting this issue and/or point me in the right direction in obtaining the proper electrical schematic(s) to repair my cool, old Gravely?
Thanks,
Mike
 
If this is the system I'm thinking of, there should be a rectifier, probably mounted on or near the sheetmetal cowling of the engine.

There will be 3 wires attached to it. Two of the wires will come from the alternator coils under the flywheel. The third wire will go to the battery.

Look the wires over, be sure they are all connected and in good condition. The wire to the battery should show battery voltage or test hot with a test light. It may be wired through the ign switch, try it with the switch on.

The rectifier can be tested with an ohm meter. With the connector unplugged, test between the battery terminal and one of the alternator terminals. It tests like a diode, which it is. With the leads connected one way, it will read some continuity, reverse the leads and it should read open. Do the same for the other lead, checking between the battery and the alternator terminals.

The problem will most likely be in the wiring or rectifier. The alternator winding rarely fail unless it's been physically damaged.

Hope this helps.
 
If after checking charging system(alt stator & rectifer/regulator)on your eng as per K series service manual & same proves to be working,do a google search for gravely 812+wiring diagram,click on link to gravelymanuals.com & download manual for 800 series tractors,on pg 29 of manual will be a wiring diag of tractor,if charging system working possible causes of battery not charging are loose/broken wire connection(s) or a bad ign sw.
 
+Some Kohler engines used a rectifier. Hal
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Use a volt meter set on AC volts. Run the engine about 1/2 throttle. See what your ac volts are, should be around 30 volts. If they look ok I think your rectifier/regulator is the problem. Be careful where you have your hands when running the engine. Hal
PS: I had that problem on a JD 140 and I cleaned the wires on DC side of the rectifier and that fixed the problem.
 

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