Hey folks..I’m have an issue with what I believe is my alternator. Car starts fine when battery is fully charged,,runs great, timing is set, but after driving for about 30 minutes or more, it won’t start back. Feels like battery is dead..if we hook up cables to jump it, it starts right up. We are running an external regulator on a 60 amp alt. We tested the voltage at the alternator at is stays pretty much right at 12v. Barely moves when throttle is engaged. It should be reading at 13+ correct? We have an amp gauge and it stays right around 12 or below. Im ready to upgrade to a 1/2 wire internally regulated. Just want some opinions before I drop a bill on a new one.
Yeah bad alternator. If I remember correctly it should read 13.5 to 13.8 when idling. Anything less and your not going to run any accessories and charge the battery. .
The amp gauge goes between all loads and the battery except the starter. It needs the show what the battery is getting not how much the alternator is charging.
I'd want to know a bit more about the car and what alternator you have now, and how it's all wired up...and the history of it, was it working at one time, and quit? or is it a new build? or ???? If the car has an idiot light, I'd either try to get the existing alternator working (some cars really need an external regulator to look right, some don't). Or get a stock replacement later style 3 wire internal regulator type. If there is no idiot light, then a 1 wire would probably be best. If it has a volt meter, then it's probably not stock gauges, so the 1 wire is looking more like what you want. As he said, just connect the volt meter to switched power.
It’s a 60amp alternator. New tbucket build. The Volt gauge did show 13-14 at one time occasionally. But now seems to just stay at 12 or just below.
Check the brushes. Easily replaced. Held up with a tooth pick. Clean the slip rings with 400 w-or-d. Windings go with the back half.. I think the front bearing is a 206. All are open I’ve found. Put in a sealed one..
Ideally an alternator should put out 14.2 volts but if it has fully charged the battery back up it is just going to charge enough to keep up with what the car pulls out of the battery. This should be pretty close to what your external regulator wiring diagram looks like. I don't see any percentage in keeping the external regulator alternator unless you just have a hardon for external regulator alternators. At O'reilly's here the Standard VR103 regulator is 56.99 The Ultima 55 amp external regulator alternator is 73.99 R111618A . On the other hand if you ask for an internal regulator 65 amp alternator for a 77 Chevy pickup it is 68.99 and maybe less. Changing the wiring is pretty simple if you don't feel like rewiring the alternator. I'm not a big fan of one wire alternators, Yes the street rodders love them because there are less wires to hide but originally they were designed for farm tractors that had magneto ignition and no key switch. They aren't better you just have two less wires to hide on a street rod. Still check the alternator out even if you have to take it off and carry it to a parts house and have it stuck on their test machine. Meaning don't start fixing things or replacing things until you test everything.
Mr48chev ,not to pick at nits but generally a fusible link is 2 wire sizes smaller ; 10ga - 14ga. 12ga - 16ga. , .To the best of my knowledge .
you stated you already checked voltage at the alternator, so that pretty much takes everything else out of the equation.
Verify voltage at the battery while engine is running, yes, I was the dumb **** who relied on the factory volt gauge that sat at 12, out a new alternator in… still was at 12. Hmnn, pulled out the meter and had 14.1 volts while running.
Your alternator has become a large , heavy pulley. To properly charge a 12V battery, the alternator has to put out a break over voltage for the battery to accept a charge. Generally that point is 13.6 - 13.8 volts. A healthy alternator will put out anywhere from 13.6 all the way up to 14.4 volts any lower and the battery won't accept the charge and any higher you stand a chance of boiling the battery.
With the engine running, touch the blade of a screwdriver to the back bearing. If it sticks there, (magnetized) , the alternator works.
Ok, thought I might have been missing something. I have re-read the thread but I can't work out what you mean. Hope I'm not the only one...
No, you are not the only one... The above post was meant for a different thread, I got my wire's crossed somewhere! I'm a Jack***... My apologies to all.
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