Manual Alternator/Voltage Regulator Jury Rig

[Albro359]

Had the same issue on a trip to Tonga some years ago...reg got wet and didn't work.
I connected 12v lamps in parallel with a jumper wire so I could have between o and x lamps in the circuit and connected it between 12v and the field and watched the voltage carefully. As the volts started to climb I would take a lamp out of circuit to reduce the field current.
I think if you used a potentiometer you'd need a big wire wound one as the field current can be as high as 8 -10 Amps @ 12v that =100 - 120 Watts...!!!

[belizesailor]

Originally Posted by Albro359

Had the same issue on a trip to Tonga some years ago...reg got wet and didn't work.
I connected 12v lamps in parallel with a jumper wire so I could have between o and x lamps in the circuit and connected it between 12v and the field and watched the voltage carefully. As the volts started to climb I would take a lamp out of circuit to reduce the field current.
I think if you used a potentiometer you'd need a big wire wound one as the field current can be as high as 8 -10 Amps @ 12v that =100 - 120 Watts...!!!

Yes, it is easy to think of the field current as small, but it adds up. I plan to go with about a 150W wire wound rheostat on my version (two of them actually to control twin alternators).

The rheostat from the stereo system worked to keep us charged up for the return trip, but it was getting quite toasty. I expect its days were numbered. Now back in port and have new regulator to pick-up tomorrow.