Hey all new to the form here and I’ve been having so many issues with my alternator not charging. This may be a little long winded but I’m at a loss and I’ve been searching forms for hours but here it goes. I have 1972 comet with a 347 stroker motor. When I bought the car the alternator wasn’t charging so I replaced the alternator and the voltage regulator just in case and that fixed it for a while. The recently my rear end went out so I let it sit for a bit while I replaced it and now the car didn’t want to charge again so I had the alternator tested and it reset good and so did my battery so I got a new regulator and nothing. I tried to jump the field wire and still no charge so I figured my wiring was bad. I replaced all the wires and went to do it again and got frustrated so I ordered a 3g alternator and hooked it up after doing a bunch of research and it wasn’t charging. I figured it was my green and red wire that goes to the alt light on the dash maybe the bulb was broken but nope it was working just fine but still no charge. I then took a shot in the dark and ordered a 1 wire kit for my 1g alternator and put it all and and it sorta works. What’s happening now is with the engine in and the batter hooked up the alternator will only charge somewhere between 12.6 and 12.8 volts but if you unhook the battery the alternator shoot’s up to 13.5 volts right where it should be with no issue. Then you put the batter back on and right back down to the lower voltage. I would like to keep the 1g alternator for now so I’d like to figure out why it’s dropping voltage so hard. I’ll do the 3 swap later down the road but I want to get this thing charging first! And yes the 12.8 volts was coming directly from the alternator.
First you should NEVER disconnect/connect battery while engine is running. High current spikes can easily damage the diodes inside alt, especially a 1G. Be sure I understand, you are using a 1G with one wire conversion? One like this? I have no idea how they may differ. https://advancetruckpartsusa.com/pr...n8g-x4Gd-TzIQ1oj3Da-RKeRdZnnMf1BoChjwQAvD_BwE Instructions are adamant about not connecting orange wire to switched 12v. The light circuit used with mechanical regulators is just about that, switched 12v. There is a 15 ohm resistance wire across bulb that serves to excite alt, later circuits in '80s went to a 500 ohm. Have you tried disconnecting the orange wire? I'm guessing it won't charge. I'd try a test light on orange wire to 12v, that'll give a load similar to later circuits. NO not one with a damned LED, you want a real #194 bulb or similar. BTW Ford specced charge voltage of 14.4v, 13.5 is under charging.
yes I am using a 1 wire conversion like that one. I currently don’t have the orange wire hooked up as I was told I don’t have to with this conversion. I only had the green and red wire hooked up when I was using the original wiring. So I have everything hooked up the way the 1 wire conversion told me to. My big problem is now is that it is charging but just it’s not charging nearly as much as it should. Like I said when the battery is hooked up it only charged about 12.6-12.8 volts no matter what the rpm is. Then if you disconnect the battery it’ll charge 13.5 no problem and increase to 14.5 with some rpm’s. I know your not supposed to disconnect the battery however that doesn’t really make sense as to why it would charge normal with no battery and under charge with the battery. Is it possible that the voltage regulator I received was just bad out of the box?
Is your battery fully charged? What is battery voltage at rest? It's common for 1G to give low reading if battery is less than approx 70-80% charged, as few have higher than a 60A output. Once battery becomes fully charged, voltage will rise. My Fairlane & Cobra both orig had 42A units, Comet with A/C had a 55A. Does your regulator have a adjustment? Stated in instructions for one I linked, it is adjustable.
It is fully charged 12.6 volts it’s brand new and I even tried the battery out of my brand new jeep to see if maybe I just got a bad battery for some reason. And the voltage regulator does have the adjustable voltage dial. That one you linked is the one I purchased but I can’t find anything online or in the instructions on how the voltage dial works and I don’t particularly want to mess with it if I don’t know what it’s doing when I turn the dial if that makes sense.
Adjusting control would have been first thing I tried. Try ¼ turn clockwise, check voltage. If voltage is too high, back of a little, not high enough turn a bit more. If voltage decreased, adj counterclockwise.
I’ll give it a try when I get home this weekend I just don’t think it’s going to work but doesn’t hurt to give it a shot
If regulator would not possibly require adjustment, they would not have included it. Admittedly it should have been set at mfgr. Mark the amount of adjustment you make, if ¼ turn makes no difference return to orig setting. Have alt tested again.
A few notes: A 100% charged battery is typically 12.6V to 12.8V Charging voltage is higher than the battery voltage - typically 13.8V to 14V (Has to compensate for battery internal resistance). Don't know your situation, but sometimes when an electric radiator cooling fan circuit or an electronic ignition conversion that uses a relay to provide full battery voltage to the ignition coil, there is a small amount of "bleed-through" current that causes the ALT light to glow. What is needed is a diode added to the ALT light circuit connected (spliced) into the regulator "L" post wire to the ALT light bulb: (Note: also "I" is used)
i understand the need for the diode of I was using the regular set up but I’m using a 1wire conversion that doesn’t need that wire.
I recently had an issue of the ALT light staying on after my car sat for a while. Alternator and Voltage Regulator swapped(even though they tested fine) did not fix it. Ran down the grounds and all electrical suspicions. I was stumped. Took it to a guy who specializes in electrical, after he retraced everything I did, he found a bad ignition switch in the column. When he 'bypassed it' the light when out and measurements on the battery while running were where it was supposed to be (14+ volts). Changed the ignition switch, problem solved.
