Alternator carnage!

[US6x4]

While disassembling my voltage regulator to replace it I found what looks like Apollo 1 and smells like the best materials that the EPA banned decades ago. It looks like the fire? originated at the #5 terminal and made everything else nice & crispy. This alternator still works pumping out 33.2 volts and I'm crossing my fingers that the new voltage regulator will get it working properly. The 1/8" pipe plug was missing from the top of the alternator and I think it's been overcharging since I bought the truck 3 years ago.

 

[US6x4]

Success! A shop vac, a flat screw driver, and some electronics cleaner got it all cleaned up inside and the new regulator went back on. I got everything reinstalled, cleaned all connections, checked the voltage at wire 568 and then started it up. I was relieved to see the needle of the gauge hover just beyond the white tick mark instead of pegged to the far right and I was glad it didn't let any smoke out of the harness.

FYI: the adjustable potentiometer on this voltage regulator had an adjusting range of 270° (3/4 of a complete turn) and a 1/4 turn was about a 2 volt difference. It had a philips head adjusting screw and did not have any clicks or detents.


It was so touchy that i adjusted it to 28.38 volts and called it good. This is what 28.38 looks like on my gauge while running:

 

[G744]

Welcome the the finest in 60A alternator design. (not).

Prestolite really got into the gov contracts with that design, and those are very prone to exactly the type of failure you experienced.

The best thing the military did to help prevent regulator failure was to run the main output wire directly to the batteries +24V.

At least the internal 3-phase rectifier bank is pretty tough, and seldom fails.

Within demand limits, the old 25A generator was known to run for years, come Hell or high water. 700 Watts of 24V power, 24/7.

G744.

 

[US6x4]

Not sure if it's the main culprit or not but when I was installing the turbo I found that the ground wire for the alternator was completely loose. Barely attached and about to fall off the frame stud.

 

[Brutacus]

Usually when someone on here experiences some of that carnage, they upgrade. Have you check out this thread from MyothersanM1. It's a simple upgrade.

 

[US6x4]

Usually when someone on here experiences some of that carnage, they upgrade. Have you check out this thread from MyothersanM1. It's a simple upgrade.

I looked through those posts and that does look like a clean, simple upgrade. Does that setup have just a 1 wire hookup?

 

[Brutacus]

No, it uses all the wires on your alternator lead, or you can tape of the sensing wire. I was also told you can wire it up in a way that bypasses the PCB.

 

[Steelreaper80]

Get a 24volt Delco clone and throw that thing in the trash. I have blown up 2 of them. Went to a 21SI clone and had no issues with 30K miles on it. If I get another truck the very first thing I will do it swap out the alternator before I even pull away from the lot I bought the truck from. I can not overstate how BAD those alternators are.

 

[MyothersanM1]

I looked through those posts and that does look like a clean, simple upgrade. Does that setup have just a 1 wire hookup?

Yes. All that is required is the connection of the #5 wire to the positive terminal.