With the engine running at a fast idle (1500 RPM or so) the voltage at the battery terminals should be 14 volts or a little more against a fully-charged battery. If you decide to adjust the regulator, be aware that the voltage setting will drop slightly when the cover is replaced due to better magnetic conduction. The unit to adjust is behind the "F" terminal and voltage is increased by raising the spring tension on the points. Some regulators have an adjusting screw, while others have a spring anchor that is bent up or down to change the voltage setting.

Be sure the cutout relay points close when the engine starts. This unit is behind the "B" wire and it disconnects the battery from the generator when generator voltage drops below battery voltage to prevent the battery from discharging itself through the generator windings when the engine stops. It sounds like the cutout relay is not closing in your situation, causing a slow discharge of the battery with the engine running.

I wrote a tech tip on DC charging systems some time ago. It's about 6 volt systems, but the 12 volt DC generator works the same way, just with different voltage settings. Good luck!

http://www.stovebolt.com/techtips/6v_charge_system/index.htm

Jerry


Last edited by Hotrod Lincoln; 03/24/2011 1:23 PM.
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