Re: Unconnected cable in my starter area. 1954 patrician

Posted by HH56 On 2021/8/4 21:37:26

The basic test you can do without specialized equipment only needs a voltmeter.

First step would be to attach the probes across the battery and measure the battery only voltage with everything off. The standing voltage should be 6.3v. If that is low and since it is a new battery but maybe undercharged due to the issues it would be a good idea to get a battery charger and bring the battery to spec before going farther.

Next step would be to start the engine and have it going at a fast idle while you measure the voltage again. If the regulator is adjusted properly and the generator/regulator is working that voltage should be around 7.4v. If it is, the charging system is at least putting out the voltage however the amperage out could be low and checking that would require specialized equipment or maybe an aftermarket ammeter gauge capable of reading at least 50 amps placed inline. Most home type volt-ohm meters have a maximum capacity of 10 amps so would not be able to do that check. If you do not at least have the 7.4 volts the next step is needed and also where it requires some speed and attention to detail.

If you do not have the 7.4 volts it could be regulator adjustment or the generator or regulator is not working. To check you need to briefly ground the FIELD terminal at the regulator while you measure the voltage at the battery again. Be sure it is the FIELD terminal you are grounding. Since this test should cause the generator to go to maximum voltage output -- probably somewhere in the teens -- also make sure no lights or accessories are on to prevent burning anything out. To keep any component stress down, do the reading quickly and remove the ground as soon as possible. If grounding does drive the voltage high, the regulator is not working or is adjusted incorrectly. If voltage does not change then the problem is the generator or field wire to the generator. To rule out the wire you can ground the FIELD terminal on the generator and repeat the test. If it still does not go to max voltage then the generator is at fault and will need to be taken or sent to an auto electric shop.

If you have no local shops there are several who advertise in Hemmings or you might get a good reference from someone on the forum. Napa might even be an option as they sometimes have a working relationship with various trades shops.