Packard Forum Index » V-8 (1955-56)

This has probably been discussed in here at some point, but I could use some input nonetheless.

For several months now I have had a problem with my generator failing to recharge my battery. I have changed my battery twice, had the voltage regulator checked, and rebuilt the generator.

Yesterday, a friend of mine was moving my Clipper around and checked the voltage. With the car off, the voltmeter read 12.65 volts. When he turned on the lights, the reading dropped. Once the car came off idle, he checked it again and it read 12.45 volts, with no fluctuation.

Here is what I am wondering: If the battery, regulator, and generator are good, is my likely problem the wiring?

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.

Thank you. This is what I was afraid of. The generator is a Delco.

I have been reading about this and I think that I ought to re-polarize the generator and see if that makes a difference. A friend of mine suggested that wiring is not likely to be the problem in this instance. I thought I would disconnect the battery, connect a jumper wire with alligator clips to the armature terminal on the voltage regulator, reconnect the battery, and then the other end of the wire to the battery terminal on the regulator just to get a spark.

If the repolarizing wasn't done when you reinstalled the generator or regulator then absolutely would be the first thing to do. If the voltages are substantially the same after the repolarizing then do the grounded field wire test.

With the key off but everything connected you can just touch a decent sized wire between the ARM and BAT terminals on the regulator and hold the connection for a second or two to do the polarizing. No need for any thing fancy.

Thank you so much, HH. You offer good, substantive advice that I very much appreciate. I will let you know how things turn out.

I was told that to test charging, disconnect the battery while the car is running. If it dies then the generator/alternator is not working. I'm guessing that your issue is polarizing. That fixed my issue.

I would think that disconnecting either battery cable with the engine running will stall the engine as the ignition system would have an open circuit just like turning the ignition key off. Also the generator's job is to keep the battery charged, not to provide current to run the engine directly.

The battery and the ignition system are both connected to the generator and they are all connected to each other. It's all one happy family.

You can run a car with the battery disconnected and drive coast to coast as long as you keep the idle up so the needle doesn't go to discharge. Likewise you can run the car with the generator disconnected electrically or belt off for many hours until the charge goes out of the battery, a shorter time if the lights etc are on.