The Stovebolt Site Forums The Shop Area The Electrical Bay charging problems

Hey guys. I had this post going once but I guess it got lost in the crash so sorry if I missed an answer. I thought my alternator was bad on my 61 283 so I replaced it but I have the same problem. I am getting zero charge. I broke the rules and pulled a cable while it was running and it died. When I turn the key on the gererator light is bright. when I start it the light is on dim and when I rev it up it goes off completly. at first it had me fooled into thinking it was charging some but now Im thinking that the battery can't keep up with the engine and the light at higher rpms. No matter how high I rev it I don't get any more than 12v at the battery. I have tried to check the alternator right at the plug and I have gotten a reading from 6-8 volts a couple of times but not every time. That is about the same as I got on the old one when I checked it the same way. I should have had it bench tested but It was old and rough looking so I assumed it was bad. I ran a cable from the ground on the back of the alternator to the battery to see if it was a grounding problem and I got the same results. I am thinking it may be a broken wire somewhere. Does anyone know if I can use a engine harness from a 62-66 that is already set up for the alternator? The alternator conversion was done very poorly. Am I right in thinking it would charge even if the regulator was bad.

If the regulator is bad it won't charge.This is an external regulator? I'm sure Someone like Hotrod (jerry) will come along and explain it to you /walk you through the way to properly check it out.

No, it won't charge with a bad regulator. The field current that turns the alternator on originates with the regulator on the old external-regulated alternators. If it's got a square 2-pin plug into the back of the alternator, you're going to need an external regulator to make it work. The black box with four connections mounted either on the firewall or the radiator core support will have a battery voltage connection, a wire to the field coil connector on the regulator, another wire from the regulator the the alternator that's involved with turning the idiot light on and off, and a fourth wire that goes to the ignition switch, IIRC. It's been a VERY long time since I worked on one of these systems, as the 10SI internal regulated alternator works so much better.

To check for charging ability, just connect a jumper wire from the big battery voltage connector at the back of the alternator to the field wire of the square plug. I seem to remember it was blue on the original wire harness. It might be marked "F" on the housing beside that connector. With the field jumpered to battery voltage, the voltage will go to
15 or 16 volts if you rev the engine. Don't overdo it- - - -I've seen battery acid actually squirt out of the vent caps from a speeded-up alternator with full field current applied. If that works, go get yourself a regulator, and a wiring diagram!
Jerry

thanks again jerry. will do

ok, I did the test and I got nothing. But, on the regulator all the wires are connected to the same hot conection and the grounds are hocked up to a bolt. the wire on the field line is cut away. I have had this truck for a couple of years and have not touched anything is this area so it worked untill recently. I could have broken a wire or something when I had the engine out but I am a little lost because what I have is not whats in my wiring diagram and doesn't sound like what Jerry described.

with all the wires hooked to the same terminal, it's been converted and should be an internally regulated alt

Bill

I was thinking that but didn't want to look like a dumb a..

If you've got a 10 SI alternator, the rectangular (not square) 2-wire plug will insert from the top or side, depending on how the rear housing is installed, not the back of the alternator. That one will function with only one jumper wire, permanently installed between the big charging lead and the #2 terminal on the rectangular plug. The other terminal on that plug is only used as a ground point for an idiot light, if there's one on the dash. An ammeter-equipped rig doesn't need any wire on that terminal. Sometimes it's necessary to goose the RPM up a little to get a 10 SI to start charging, depending on which regulator assembly is installed in it.
Jerry

Ok, on my truck I have the big red charging wire that runs down to the harness. Ir reads 12 volts with the key on and when Its running. On the plug it has a smaller red and black wire. the black bolts to the housing and the red also runs down into the harness which is rapped up so I can't see where it goes. Im thinking since the large wire has power that the small wire might be broke before it meets up with the large. If I am correct then I should be able to cut it and connect them together on the back of the alternator and it should charge. I hunted down a picture of the back of one and thats how it was set up from the factory but it was from a newer truck. the only thing is the jumper wire is about half the size as the other wire. Am I on the right track? If I get this right I am going to order a new harnesses for the engine bay before I start a fire but I wan't to find the problem first.

The black wire to the housing is wrong. It should be the ground for the idiot light, coming from the dash. You can cut the red wire off and jumper it to the big charging lead on the back of the housing, as that one needs constant 12 volts, not even necessary to be turned on/off by the ignition switch. If there is a no charge light on the dash, one of the wires to it goes to ignition, the other goes out to the alternator and grounds with the black wire anytime the alternator is not charging.

Here's a good article, including pictures, about the 10SI and 12SI alternators. Does yours look like one of them? If so, the wiring connections we've been discussing will work.

http://www.madelectrical.com/electricaltech/delcoremy.shtml

Here's a good "how to" about wiring the 10SI.
http://www.oldengine.org/unfaq/10si.htm
Jerry

Thanks Jerry. Thats the one I have and thats the how too that I needed.