I have a 1940 mercury with a 6v positive ground system I currently replaced the generator with a rebuilt one and also replaced the regulator on the fire wall. I figured I would start the car and boom I'd be back up and charging. I'm currently only getting 6.5v max. I flashed the regulator while the car was off removing the field wire to the regulator and touching it to the battery terminal until a spark and then hooking field back up and that did nothing. I tried that 2 to 3 times. I am currently stumped and trying to figure out why I'm not charging with new parts. Are there some tests I should do to the generator or regulator? If using a volt meter on 6v please be specific because the positive ground things confuses me. Not sure if I could use the positive part of the volt meter to the ground and then negative part of volt meter to the power Thanks for any help. Here is a video if you see anything that looks wrong
Here’s an old back yard test, apply 6 volts to the output post of the generator with a set of jumper cables, with out the belt on, and see if it spins. If it does, your problem is not the generator! Might not tell you what wrong, but it can tel you what’s right! Bones
If you temporarily ground the field terminal on the Genny, with the engine at a fast idle, it should peg the ammeter to full charge. This confirms gen is good, so fault is likely at the VR. If your battery is fully charged and all you are running is the ignition the cut out circuit will not be demanding a heavy charge rate. What happens when you turn on the lights and or hi beams? Don't leave the jumper wire on the field terminal longer than necessary to do the test. What size primary battery cables are you using??
Generator charging systems are simple as it gets. Don't let it kick your ass. Usually when these things come up what happens is someone here will type up detailed troubleshooting instructions, and the OPs eyes glaze over and he goes and picks up an alternator. @squirrel has a web page with some generator info. I would suggest studying that, the Shop Manual for your car, and old MoToRs Repair from the period. The troubleshooting trees are usually pretty good. Just keep the Ford/Mercury type "B" charging circuit in mind. The idea is to isolate first the trouble to either the regulator or the generator. I would suggest also getting used to the idea of using the analog type of meter. A digital unit will work for just checking voltage output, but it will display gibberish when you start getting into it more in depth. I will say once everything is first setup according to Hoyle they work fine, usually people slap on stuff that's been laying around in the weeds. Don't try to "adjust" the regulator. If it's a modern repro, that may be the problem. Good old school NOS or serviceable used regulators.
Pretty sure on a Ford you have to supply power to the generator field to get the generator energized. You ground the field on GM products.
You say you are getting 6.5 volts max. Where are you measuring this? You may want to measure the voltage at the armature wire on the regulator and at the battery wire. The voltage regulator contains a cut-out relay. It's job is to disconnect the generator armature from the battery when the voltage output of the generator drops below battery voltage. If you have higher than battery voltage at the armature wire, but not on the battery wire, the cutout relay isn't working. This is a problem I have run into with the voltage regulators available today. You can full field the generator by disconnecting the field wire at the regulator and touching it to power, in this case battery negative. If you get 7 or 8 volts a the battery negative terminal, the generator is working and you problem lies in the regulator or wiring. If not, the generator is the problem.
Last night when I checked the voltage at the armature wire on the regulator it was like 3.5v or something. That made me think the generator isnt functioning properly I just installed it yesterday and it's a rebuilt one that's been gonna shelf for I'm sure many years What steps should I take to test generator or "charge it up" or whatever it's called
I wonder if the regulator contacts are oxidized from being on the shelf for so long? Cleaning them is tricky, you need to get the oxidation off, but not damage them, or bend the adjustments. http://selectric.org/manuals/generator/index.html .
Yes, but make sure your belt is off, the generator will “ motor” but not as fast as a starter, but will spin at a nice rate and smooth if the generator is good. A rock solid test of a generator. Also brushes can stick in a generator, especially one that has set on the shelf for years. Make sure they are movable. Bones
I won a rebuilt 30 amp generator at auction from EvilBay, a couple few years ago, the sticker said 1989. It did work, and sported a nice coat of paint, though among the defects found, the new brushes were installed as supplied, i.e. "square". I didn't catch this because it was rebuilt, after all. That's what I pay people good money for, instead of doing it myself. Their expertise, attention to detail, and their pride in workmanship. Yeah, yeah I know, take another bong hit - that's the idea, anyway. New generator brushes require sanding so that the surface conforms to the commutator and presents a full contact patch for good current transfer. Normally carbon brushes last a long time, thousands and thousands of miles. These arc'd and burned within just a few hundred miles.
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