Alternator overcharging

[tallyho8]

I have a one-wire Delco alternator on my diesel IH364 that is not regulating anymore. It charges almost 30 amps all the time and will quicky boil all the water out of my battery.

I don't know if this is something that is easy to fix or not but I am too busy (lazy) to fix it if I don't need to. I was wondering if it would hurt anything if I simply put a toggle switch on the one wire and turned it off most of the time so it wouldn't charge and just turned in on for a few minutes while I was using it to charge back up.

[Treemonkey1000]

I would take the time to get it fixed so that it doesn't damage anything else. Sounds like something is shorted to draw 30 amps out of the alternator. Dead cell in the battery, pinched wire in a harness someplace, shorted diode in battery. Those things come to mind. But I wouldn't let that continue and ignore it.

[RonMar]

What is the actual voltage at the battery when running? If it is constantly feeding 30 amps, it sounds like the voltage regulator is fried. You might be surprised to find that the alternator is currently outputting a really high voltage(18-20+V). The battery boiling and absorbing the excess energy is probably the only thing keeping any other electronics in the vehicle from frying. I bet your lights are really bright too... This constant overcharge also outgasses a lot of hydrogen gas, which if provided a source of ignition can cause a battery explosion.

The AVR on a one wire is internal, and you may be able to get just that part, but is anything else wrong with the alt such as a diode in the rectifier? You might be able to overhaul it yourself cheaper than a replacement, but it can be an involved process splitting the case. I would say it is probably way easier to replace the whole assembly.

I would not put a switch on the alternator output circuit. First off you will need a big switch(30+ amp?). If the regulator is still partly working, disconnecting the load causes voltage spikes that can finish frying the regulator and you won't have any idea what it is outputting when you switch it back on. Also if it is putting out a higher voltage into the battery load now, when you disconnect it, the voltage will go up. When you turn it back on, you may send a high voltage spike into the system that will frag other electricals such as electrical engine instrunments.

I would suggest you do one of he following:

1. Replace the alternator and restore the system to normal.
2 you could disconnect the alternator completely, and add a small plug in trickle charger to keep the battery charged when it is parked. As long as you don't need lights for any significant ammount of time, and only need to start the engine, this will work. I have seen people do this for years on electric start mowers and small machinery.

Good Luck

[Mickey_Fx]

Originally Posted by RonMar

What is the actual voltage at the battery when running? If it is constantly feeding 30 amps, it sounds like the voltage regulator is fried. You might be surprised to find that the alternator is currently outputting a really high voltage(18-20+V). The battery boiling and absorbing the excess energy is probably the only thing keeping any other electronics in the vehicle from frying. I bet your lights are really bright too...

Had to walk away from the computer for a while and now see Ron saying exactly what I was thinking.

Check the voltage and if much more than about 14.3, my money is on the VR being shot. With these one wire models that usually means replacing the alt.

[tallyho8]

Just checked my voltage. New battery = 12.4 volts off. 14.4 volts at idle and 16.4 volts wot. I don't have any lights or electrical equipment except for the starter, alternator and amp guage.

[ScottAR]

I'd just change the alt. They're only about $30-$40. I had a regulator go south on the 1050 once and blew the top off the battery. That will wake you up let me tell ya.

[RonMar]

12.4V is OK before startup, 14.4V is perfect at idle, but the voltage regulator should be maintaining that mid 14V throughout the RPM range. Again suggestion 1 or 2, I listed above applies...

Good luck

[Soundguy]

Get a new alternator.. or have that one rebuilt.. save yourself the hassels.. get a delco 10si 3 wire job.. They are soooooooooooooooooooooo ez to hookup. Really just 1 extra wire.

Charge stud hookup stays the same. #2 wire loops to charge stud.
#1 wire goes to a 194 bulb, then to switched side of the ignition.. or #1 wire can go thru a diode to the switched side of the ignition. Marked side of diode ( cathode ) towards alternator. any diode capable of handling 1a/50piv will work.. 3a/200piv is better. A radio shack 276-1661 will work... a 1N5408 will work.. etc..

The toggle switch will just let the alternator charge voltage go sky high and it will likely quickly flame-out on you..

soundguy

[tallyho8]

Thanks to everyone for recommending that I get my alternator fixed. It only took a few minutes to remove and I brought it to a local alternator shop and they only charged $30 to replace a diode. Now it works fine and I don't have to worry about it anymore.

PS It wasn't a Delco one wire alternator. It was a Lucas 3 wire and many years ago someone had removed 2 of the wires. It still works fine with just the one wire. When you start it at an idle it doesn't charge but the second you increase the engine speed it starts to charge and remains charging correctly at all speeds. The shop told me how to connect it up right so that it will charge from the second it starts but that is a lot of trouble to go through for no reason because it has worked fine like this for the 16 years that I have owned it.

[Soundguy]

I hope one o fthe 3 wire connections isn't external sense.. if so.. It's likely to go out again as charge voltage can go high-er than needed without external sense lines hooke dup. also sounds like it has the capability to use an external excite line.. Hooking up one line is not a whole lot of trouble, considering it makes the alternator run correctly as it was designed.

I fix electrical stuff day in and day out that people use incorrectly.. so when i see stuff like this i feel i need to make the comment.

Soundguy