siebertl

Ok, I've disconnected my heater so all is back to stock. Three weeks later, yesterday, I get in the truck, turn it over and notice that the batteries were near dead, it started, but barely. I ran the truck about 30 miles, turning it off once, started back up barely and there wasn't enough juice to keep the radio on. I ran it 7 more miles home, dashboard voltage guage read about 10 volts. When I got home I tested the alternator output and it was under 12volts. It ranged from 10-11 volts. I've had the alternator tested and checked out by advanced auto and paid an alternator guy 40$ to go through it. Both batteries are new.

It's like it charges but at too low of voltage, and over time the batteries get sucked down. Is this a voltage regulator problem?

bones7977

I had the same problem and believe it or not it was the starter pulling all the power from the system. Its worth a try..

infidel

Install an external voltage regulator, any 12 volt one will do and should cost under $20.
Instructions> http://www.cumminsforum.com/forum/94...w-89-02-a.html
and
https://www.dieseltruckresource.com/...n&onlynewfaq=1

siebertl

I have the external regulator hooked up. Just to check my wiring, I'm using the pyramid dodge/chrystler style regulator as indicated by infidel's second link. I assume the two leads go to the 2 small terminals on the alternator right? I'm a little confused by infidel's first link in regards to the ford regulator, it is hooked up differently.

Initial test: when I start the vehicle I only get 12.01 volts fluctuating to 11.43 volts at the battery. Under power, at speed, my dash voltage gauge reads 14; I like that. After a few miles, back in the shop, the dash gauge drops and with a meter at the battery I drop back down to 12. 01 volts.

Guys, when you start your trucks, what does your battery voltage read? I understand there is grid heater draw initially, but I did unhook the small green and red wires on top of the relay to disable the heater grid and there was no difference.

My thoughts are that the batteries are a little drained due to running with insufficient charging. Which is why at about once a month the batteries would finally drain down to the point of not starting. I'm hoping after running for a while, and bringing the batteries back to life, I will have sufficient charging at idle.

infidel

Use the small wire posts, tape the stock wires (not together!)
Most important is the switched hot wire is at the top of the triangle.

siebertl

I've been running the external voltage regulator for a month now and today I had dead batteries again. I have noticed they were getting weak for the last 3 days. I have noticed that the in dash voltage gauge still reads low (10-13 volts) when at low RPMs which is most of the time. If I run the truck with overdrive off the volt gauge reads above 14 like it's actually charging the batteries. When I bring the alternator to advanced auto and they test, it comes back as good. I'm still wondering, is it possible that the alternator is just to weak to push enough voltage at normal (low) RPM?

VICIOUS FISHER

[QUOTE=siebertl;2714060]I've been running the external voltage regulator for a month now and today I had dead batteries again. I have noticed they were getting weak for the last 3 days. I have noticed that the in dash voltage gauge still reads low (10-13 volts) when at low RPMs which is most of the time. If I run the truck with overdrive off the volt gauge reads above 14 like it's actually charging the batteries. When I bring the alternator to advanced auto and they test, it comes back as good. I'm still wondering, is it possible that the alternator is just to weak to push enough voltage at normal (low) RPM?[/QUOT

seeing as you have just about covered everything, yep the alternator could have low output at low revs, also has the pulley been looked at? right size? did you get the right pulley diameter after the alt rebuild ?
I am not sure about this but is it taper fit or keyway? as I haven't looked at mine but could the keyway be spun/taper not right? and the pulley is slipping ....just a thought

siebertl

After about a year of chasing this problem, I figured out it was the alternator. This was an alternator that tested fine at advanced auto and by the guy who rebuilt it. I called him back after he cleaned it up and told me it was the external voltage regulator. After adding the external voltage regulator the problem persisted, I called him back and he put a different chassis in it. Back to the stock voltage regulator now and all works great. He tested the alternator the first time and it tested fine. Just wanted to get this out there to those with the same problem. Even though the alternator tests good, it might still be a problem. Mine just wouldn't charge at idle or low RPM's.