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12v charging system sky high

Duallykid

Duallykid

More Wrench time than mileage
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Location
Baltimore, Maryland
My volt meter is showing just under 14 volts while running, using a test meter my batteries are showing 19 volts, okay so the factory gauge it wrong, no problem, But I'm gonna fry shit up and I really don't want to. can I adjust the voltage regulator on the alternator?
 
To my knowledge voltage regulators haven't been adjustable since the late 60's, early 70's.
 
I'm taking a guess on the 6.5. Moved here for now.
 
buddy said:
I would test the accuracy of that test meter, its lying to you, if its analog maybe the needle is bent?
Click to expand...

X2. Take a reading with the engine off. Should be 12.8v to ~13.5. Closer to 12.8v 30 min after the engine is off.

How old and dead are the voltmeter batts? This makes em read wrong. :eek:

If you really have 19v engine running the alternator's regulator is shorted.
 
Is it getting that voltage while running at one or both batteries?

If it's at both, I'm surprised the batteries havn't exploded yet.

If it's only at one battery (likely the passenger side), then check the slave cable between the batteries.

Other than the alternator, start checking grounds.
 
lol sorry i have a cummins too. and it is tested with the engine off and i'm getting 19 volts any where i test it. (both batteries, hot wires in cab, trailer plug, hot post off of the alternator) so what about the grounds?, i just put new terminals on the cables too, because they were over tightened and stretched out so they were all loose on the battery posts. it would crank slow sometimes barely crank at all, and the terminals would smoke a. so they're all new and all the grounds are tight
 
Duallykid said:
lol sorry i have a cummins too. and it is tested with the engine off and i'm getting 19 volts any where i test it. (both batteries, hot wires in cab, trailer plug, hot post off of the alternator) so what about the grounds?, i just put new terminals on the cables too, because they were over tightened and stretched out so they were all loose on the battery posts. it would crank slow sometimes barely crank at all, and the terminals would smoke a. so they're all new and all the grounds are tight
Click to expand...

19 volts with the engine off means most likely you have a bad meter.
 
Did you test other batteries at 12V since you tested this?

You would have most likely fried your TCM at 19V, most things are only rated to like 16V.

If you check the meter and its correct or use another meter, then its simple the voltage regulator on the alternator has failed. Check your batteries after its been sitting a long time.
 
I would use another volt meter first.

19V will destoy all your electical in short order. As was stated, over 16V and things are getting cooked.

If it's cranking slow and you're seeing higher than 14.5 volts while running, then the batteeries are probably shot and the regulator is seeing that and it's trying to compensate by turning up the voltage output.

But, before you start throwing parts at it, you need to make sure the volt meter is accurate.

Engine off, you should be seeing ~12.5 volts.

Engine running, you should be seeing ~14.2 - 14.6 volts.

Honestly, if it was more than a few miles and you were making that kind of voltage, the trucks electrical would be toast. The batteries would have exploded from overcharging.
 
94-98 CUMMINSwill have a PCM controlled regulator, so replacement is NOT cheap. Find another meter first, or go to ADVANCE or AUTOZONE and have them check the batteries and charging system. 19 volts WOULD EXPLODE that battery in short order, not just boil it over.
 
Arghhh, I dislike Dodge and their PCM voltage regulators. We are back in the Cummins area, wooops.

So we have no idea what the truck config is, is this mechanical injection with a manual tranny? Something that would not have any PCM, or what year is it? Need to put it in the signature.

If its PCM controlled and the PCM is actually the issue then yes you could instead wire in an external one, like from an older Ford. I had a brother's Dodge at a shop that told me PCM wasnt working to regulate the alternator and they wanted to replace PCM. So I wired in an external, then later found the wire that was broken. Bastards lied and just wanted to make money on the PCM sale.
 
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