Cat overcharging

[Old Growth]

Dozer overcharging.
We have a 1972 D4D Cat that is a Mitsubishi/Japan made tractor. It has Mitsubishi electrical/alt/gen on it.

While running it today the ampmeter was higher than usually and once I shut her down, I noticed the finals on both sides were wet. After better inspection, I determined that the batteries were boiling and weeping down onto the finals.

Any pointers on what I should be looking for or looking at first?

Thanks

 

[Vetech63]

It would be nice to get a voltage measurement to see what your current charge rate actually is.

 

[Old Growth]

It would be nice to get a voltage measurement to see what your current charge rate actually is.

I can do that next time I’m over there.

 

[Delmer]

12 or 24V? get the voltage measurement at the batteries before you start, then at the alternator with the key on, engine off. Then at the alternator with engine on. All the terminals on the alternator. If it's 24V, get each battery's voltage also.

 

[ozarkag]

Any pointers on what I should be looking for or looking at first

Alternator

 

[Tyler d4c]

And here I thought this was going to be a thread about the rate dealers charge!

 

[Old Growth]

It would be nice to get a voltage measurement to see what your current charge rate actually is.

left batt at rest was 12.66v
right batt at rest was 10.71v
combined at the switch at rest was 23.2v

left batt while running is at 17.35v
right batt while running is at 16.75v

Napa Commercial Cat size batts. Within 2 minutes of starting it the caps start bubbling.

I didnt have a chance to pull the side cover and check at the V at the ALT last time I was over there.

 

[Dave Neubert]

Voltage regulator on back of alternator

 

[Welder Dave]

I've always heard over 14.5-14.6 volts charging on a 12 volt battery is when you run into problems. It looks like you have 1 bad battery though. I'm not sure if 1 bad battery can affect the charging rate of both batteries?

 

[Camshawn]

Yes, one bad battery will cause the good one to overcharge. The water usage will be much higher in the good battery. A voltage drop test on each battery will prove one is shot. A hygrometer will show a bad cell as well if it is not a sealed battery. Cam

 

[nicky 68a]

I thought you meant Cat were over charging for parts

 

[Delmer]

He has one bad battery, and both being overcharged. This is not just one bad battery causing an issue with the other one.

 

[Old Growth]

So an update.

I pulled the alt and reg and went to RE electric and they had a hard time figuring out how to test it since they had no drawings/schematic for the old Mitsubishi stuff that was on there.
CAT could not get the regulator, NLA with no updated replacement number either.

So at RE we stated getting alternators out and eventually we found a new one wire Delco style that was the same exact dimensions on the top and botttom mounts. The cat pulley was the same diameter center hole for the shaft. Also the distance/offset to the front was the same also.

It was a perfect fit for the D4D.
The part number is 8367N. It’s a pretty common alternator used on many newer trucks and equipment.

It now charges at 27.4v and works perfect.

 

[Old Growth]

Here is the Alt.