About John Campbell Expertise I am an expert in body repair and restoration. This includes electrical and mechanical. I can also be coaxed into finding hard to locate parts for interesting marquees.
Question Hi John. I have a 1977 Graveley rideing tractor that is burning up batteries. The engine is a 16.5 HP Onan. Their is a rectifier/regulator located behind & under the flywheel on the back of the engine. I am reading 18 volts across the battery terminals with the engine reved to mowing speed. Obviously the regulator is not cutting the voltage down or cutting it off when the battery is fully charged. Onan wants $750.00 for a replacement part. Seems to me that sense I have plenty of voltage, a simple automotive regulator from an older vehicle can be adapted. Problem is these regulators don't come with wireing diagrams. The local auto parts suggested an 84 ford truck regulator which has 4 push on terminals labeled I A S F left to right. The regulator on the tractor has 4 wires. I have a diagram from Onan showing them from left to right, Yellow, Black, white, Yellow. The 2 yellow come directly from the Flywheel alternator to the regulator. the black goes directly to the battery positive terminal, & the white to Ignition. Any idea on how to adapt this to this new regulator? Also how to determine if it will cut out when the battery is charged. Possibly a different regulator? If you have fax capability I can fax you the wireing diagrams that I have. thanks for any help that you can offer. Jim Langlois
Answer Ignition, Alternator, Stator, Field
Ignition, white wire.
Alternator Output, Black wire.
Stator, yellow wire coming from stator assembly "woven wire ring"
Field, coming from alternate side of stator.
If you cannot identify the field and stator you can try looking at the diagram for the onan to determine which one is energized when the key is on.
Regulators never stop the current flow, they only regulate it. You can try it, but I would try to find an onan regulator from a small engine and industrial warehouse or try going to NAPA. You would be surprised what you can find at NAPA.
