Alternator issues

[69gladiator]

Over ten years ago I replaced the Motorola external regulator alternator with a Delco 10 si. It had worked flawlessly until about six months ago. The alternator wasn’t putting out any voltage so I replaced it. The new one was running about 16 volts which I think is too high. At the battery. I was only reading 12.4-12,6 volts. The new alternator then crapped out and I replaced it again. I’m getting the same numbers again with another 10si. When I turn on the headlights, the voltage at the battery drops to 11.6 volts.

I’ve checked the wiring for obvious issues and repaired what looked to be out of order.

I’m about ready to switch the three wire over to a one wire. I did it on my cj5 and it works great.

[tgreese]

If it worked and then it didn't, something has changed. Either the alternator failed internally, or your wiring is broken or corroded. In either case, changing the alternator to a one wire might fix it, but has nothing to do with one-wire over 3-wire.

[will e]

On my 83 the resistor wire gave up after all of these years and the heat under the hood. It was just a single strand and couldn't take the heat. It was intermittent for a while but finally broke. So I bit the bullet and finished my CS140 swap and added a resistor adapter. What a great upgrade!

[tgreese]

The resistance wire is a length of single-strand nichrome wire, like you'd use in a toaster. It can be replaced with a fixed resistor, or a diode, or a light bulb (that's how an alternator light works). Easy to test with your multimeter.

I would point out - this is the exciter wire and does not affect the regulation. Once the alternator starts charging (excites), the exciter connection does nothing.

[69gladiator]

I went back and rechecked the wiring and found that the wire between the alternator and the solenoid formed corrosion inside one of the ring connectors. At first glance it looked fine. This was a tough one. Thanks for everyone’s input.

[tgreese]