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Location: Muskego, WI | I'm having charging issues with my 1956 Imperial. My car has several modern updates, including electric cooling fan and fuel injection. I'm using a 130 amp Mopar squareback alternator and mopar voltage regulator. When the car and alternator are cool, everything is great. I have 14 volts at idle and it keeps up with all my electronics. However, as the alternator warms up output falls off. The engine will still be relatively cool but the alternator will get as hot as 165F and my voltage will slowly drop from 14 down to basically battery voltage (12.5) or less in a matter of 5 or so minutes.
I have confirmed I have excellent grounds from the alternator to battery and voltage regulator to battery. I have tested the voltage regulator by directly grounding the alternator field wire to the battery. When the alternator is cool and putting out 14v, the voltage output will jump as high as 16. However, once the alternator warms up a little bit and the voltage falls down to 13 or less, jumping the alternator field to ground does not bring voltage back up.
Based on this, I'm thinking my alternator has bad (or failing) diodes. That would explain the falloff and the heat, but just thought I'd check here in case anyone else has any other thoughts. Unfortunately, the alternator is only about a year old and has little mileage on it and it was even US made. |
Voltage falling off
