Re: Problem with charging battery

Posted by HH56 On 2016/10/5 12:19:01

The voltage when at a fast idle is low according to specs. For Delco, at 1600 rpm (2000rpm for Autolite) the generator should be putting out 13.8 to 14.8v at 70 degrees F.. At your 12.45v the voltage is lower than the average standing battery voltage of 12.6v so the lights are drawing current and generator appears to not be charging at all. If the battery is fully charged the voltage will be at the low end of the range but still should be equivalent to slightly above the standing voltage.

To see if the generator or regulator is at fault momentarily short the field wire to ground while you are monitoring the voltage at the battery terminals. With the field grounded the generator should put out maximum volts of close to 15v. If it does go high the generator is functioning and problem is at the regulator. If no change the problem is with the generator. Do not keep the wire grounded any longer than it takes to get a reading.