The Stovebolt Site Forums The Shop Area The Electrical Bay Another generator/charging problem

12v in 1952 235 My ammeter gauge would show charge and then drop to a discharge when lights were on. After a few days of this the battery was dead. All new wiring recently. Voltage at battery was up to 14 volts, now steady at 12 to 12.5. Meter never shows a charge now. Supplied power to generator and it did turn like a motor. Cleaned all three points on the regulator with news paper, not a file. Still does not show a charge. Battery voltage at 12. What do I look for. I am thinking regulator but can not find a 12volt to replace it.

Bart Bosco: A couple of things to try. 1, Check the battery. Under load, easy to do. Turn on the lights and put a volt meter across it. Should be 12-12.5 steady. If that is good then try the armature output voltage. If you have a generator. should have something like 12 volts out. That means you have a working generator. If that is good then follow the regulator adjustment procedure in the shop manual for a 55 second series truck. If the regulator is bad you can replace it with a 12 volt regulator from any parts house. Then polarize the gen and start testing the voltage at the battery. Should be around 14.5 volts at a high idle. If it is not you may have a bad generator as well. The regulator feeds voltage to the field coils to increase output under load. Permanent magnets will still cause the generator to put out voltage even if the field coils are bad. Just not enough to charge the battery under working loads. That is why the regulator adds voltage to the field coils. Makes stronger magnets when needed. You could measure the field coil resistance but it is not very much just about 2-5 ohms and even then you would not know if the coil is shorted. If the armature is bad no volts out at any time. And that includes the brushes. You can fix the generator. Any shop that does starters can do it for you. The regulator is not hard to find.

I read that if I put power to the generator ARM terminal and ground the field terminal that a good generator would turn like a motor running. I did this with the belt loose and the generator did turn there fore I assume the generator is good. Is this a correct assumption? This also should polarize the generator I was told.

I have read about making an electric go-cart using a 12 volt generator wired backwards. You just needed the right diameter driven pulley on the axle.

Here is a test that you can do. While measuring the armature votage at the regulator, momentarily ground the field of the generator. That should make the armature voltage come up assuming thre engine is turning above idle.