Ammeter Suddenly Shows Charging

F4RM@11

Member
After getting the SM started again following a carb rebuild, I turned to the electrical system to troubleshoot the lack of charging. The VR output had been adjusted and the gen inspected by an auto electric shop - both had a clean bill of health.

The ammeter showed a slight discharge with the ignition switch on and the needle didn't move with changes in engine speed. Following Bob's troubleshooting flow chart, I made it through to the last step before the ammeter began showing a charge.

When I jumpered the BAT and GEN terminals at the regulator, the ammeter suddenly began showing a charge and continued to do so afterward. The needle moved appropriately with engine speed.

I'm curious as to why a charge on the ammeter suddenly began to show after making this brief circuit. The battery was fully charged after I returned to the shop as the trickle charger indicated so.
 
Shut it down and start it up again. Does it still charge?

I had the same problem last year, and it was a bad regulator.
 
(quoted from post at 15:45:36 11/17/12) Shut it down and start it up again. Does it still charge?

I had the same problem last year, and it was a bad regulator.

Yes, I had it shut down a few times today, one of which was for 30 mins or so. The ammeter continued to show a charge after each start. I'm not complaining - just curious to understand what happened.
 

:oops: I feel silly for not knowing that since it says right on Bob's troubleshooting flow chart. Duh! Thanks.
 
Your generator was likely polarized backward; jumpering BAT and GEN terminals fixed that.

Could also however be an intermittant problem involving the regulator ground - especially if the regulator is in the stock location bolted on the front of the steering wheel stanchion. (The Super M is notorious for VR grounding problems here.)

Suggest running a #14 ground wire from the regulator base to a GOOD frame ground - ideally where the grounded battery cable is attached.
 

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