Yet another CUCV charging issue: overcharging

[Power Giant]

Long time CUCV user, and fleet owner here. Went through the entire sticky thread on the CUCV charging system. Overcharging was not mentioned in it. On one of my M1008's, the rear battery is consistently boiling. Anyone here seen this before? Is this a clear cut case of the voltage regulator on alternator #2?

 

[Warthog]

Without a voltage reading it is hard to tell. Most like is a bad voltage regulator on GEN2. They should be around 14.8v

 

[Power Giant]

Without a voltage reading it is hard to tell. Most like is a bad voltage regulator on GEN2. They should be around 14.8v

Copy that. And if I need to replace the #2 alternator, I need to specify that it is an isolated ground unit, correct? I saw a part # from a different thread: Delco 27 SI, type 100, 100amp. Does this sound good?

 

[doghead]

Rebuild it. regulators go for around 8-20 bucks.

 

[Warthog]

The 27SI is just the housing size. The Type 100 is just 100 amp.

The GEN2 alternator has to be built as an isolated ground. If not some big fireworks will happen.

Here is a kit that I have used many times.

http://www.aspwholesale.com/index.php?act=viewProd&productId=5137

 

[Power Giant]

The 27SI is just the housing size. The Type 100 is just 100 amp.

The GEN2 alternator has to be built as an isolated ground. If not some big fireworks will happen.

Here is a kit that I have used many times.

http://www.aspwholesale.com/index.php?act=viewProd&productId=5137

Thanks for that link. What do you think of this: Ditch the stock alternators, install 2, one wire Delco 12 volt alternators. One to each battery. Install a voltmeter for each battery. Don't you think that the stock charging system is unnecassarily complicated?

 

[Warthog]

That will not work with the way GM wired the truck. Others have tried and failed. Grounding is the issue.

The charging system is very simple once you understand it. It works very well for what it was designed to do.

 

[Power Giant]

That will not work with the way GM wired the truck. Others have tried and failed. Grounding is the issue.

The charging system is very simple once you understand it. It works very well for what it was designed to do.

I see what you mean about the grounding issue. What about going with one 24 volt alternator to replace the two twelve volt ones?

 

[doghead]

Well, your truck is mostly 12 volt.

You can't charge 2 batteries in series and draw off one(for long).

 

[doghead]

You may simply have a bad battery.

Test it.

 

[Warthog]

Why not just fix the problem?

Or you can always convert to 12v only. Use the Rosscommon Equipment method.

View attachment Rosscommon Equipment.pdf

 

[doghead]

I still don't understand why nobody wants to convert to 6 volts.

We used it for years and it worked just fine.

Never fix something you don't understand, just change it(without knowing how or why).

 

[Warthog]

They are designing new cars that are 36v and 48v. The Hybrids are 300+v. What will we do then?

 

[Power Giant]

I still don't understand why nobody wants to convert to 6 volts.

We used it for years and it worked just fine.

Never fix something you don't understand, just change it(without knowing how or why).

I can see having the 24 volt starting system for cold weather starting, but that's it. Two of the CUCV's in our fleet have already been converted to 12 volt and have had zero issues. Like I already stated before, the CUCV charging system is unnecessarily complicated. Just because some engineer designed it doesn't mean its correct. I encounter sub-par engineering mistakes on a daily basis. When I get the chance, I make them right.

 

[doghead]

What was the point of posting this thread?

It seems like you already had your mind made up.

We want to help you, but your not asking for help.

You may have a bad battery, it could be that simple.

You need a $10 part and 20 minute fix.

You should just change it to 12v, as you have the rest of your fleet.

What was this thread about?

 

[Recovry4x4]

Unnecessarily complicated? Yikes. Any 12 V alternator can suffer a regulator failure. The system is only marginally more complicated but has many benefits.

 

[Power Giant]

What was the point of posting this thread?

It seems like you already had your mind made up.

We want to help you, but your not asking for help.

You may have a bad battery, it could be that simple.

You need a $10 part and 20 minute fix.

You should just change it to 12v, as you have the rest of your fleet.

What was this thread about?

This thread is about me asking for input on CUCV overcharging on the rear battery. Some folks have been extremely helpful to me, thanks to those folks.

 

[Ilikemtb999]

I had the same issue with my gen 1 alternator. I replaced the voltage regulator and all was fixed.

 

[Power Giant]

I had the same issue with my gen 1 alternator. I replaced the voltage regulator and all was fixed.

Thanks for the input. I had a brand new alternator on the shelf: Wilson 90-01-4277. I swapped it out with the #2 unit and it stopped overcharging. I will stock a rebuild kit from now on, though.