BassHeadBiondi

Alright I have a 320amp alt on my 96 XJ. It is pushing about 18v into my cab. Should I worry about anything in my dash or even my ECM? All help is awesome.

firehawk618

Yes, anything much over 14.5 can damage components.

BassHeadBiondi

It's been like it for about a year with no problems YET. Is there anything I could do? I ain't going to remove the alt.

salad

I am surprised that you haven't killed your Jeep yet putting out that much voltage. Never mind the PCM, you're into "battery can literally explode" territory. You are playing a dangerous game. ****ing with electricity can kill you.

Have you measure this with a multimeter and found it accurate? If it is, it sounds like you didn't hook up the field generator wire and this alternator is running without regulation. What does it say in its manual regarding voltage regulation?

Rogue4x4

If you're hell-bent on not removing it, why did you even ask the question?

Take salad's advice to heart: Electricity can and will kill you. Maybe not from the voltage, maybe not from the amps, but the wiring in your jeep is overloaded, and the wiring loom is basically a giant fuse. What happens to a fuse when it blows? It burns up. Yeah, your harness can burn up, and cause a fire, and that can kill you...

Verify that the alt is installed correctly. With all the right components to make it work properly. If you don't know how, take it someplace that does. You are playing Russian roulette with your electrical system.

.02

BassHeadBiondi

The mechanic said the battery is fine. The alt won't over charge it because it somehow knows when it's full. When i use the multimeter on the battery is only 14.4 so that's ok.

The alt got professionally done. It's been in there about a year and nothing has blown or burnt. My friend has 3 alts on his. A 320 and two 260s and he has had it for about 3 years with no problem.

ehall

Where did you get the 18 number from?

BassHeadBiondi

I got 18v from the sun visor wire. And I got 17.3 on the wires that where hooked up the the roof where the compass and temp was.

BassHeadBiondi

And the light in the glove box read 18.1. Shouldn't the regulator regulate the power to the objects being powered? For example: The wire for the sun-visor isn't being used so there is nothing connecting to it so the alt is sending full power but the radio since it is hooked up should be telling the regulator it only needs 12 or so volts. That is what I'm thinking. I only tested wires that Where not being used.

caged

if you are overcharging, you better get an adjustable voltage regulator on there. you can run the dial in the cab with a meter to keep the volts at about 14.4.
you also need to change out your stock cables for 8-12 awg cables to keep the current flowing.

but seriously, why do you need that much power? are you running amps and subs?

BassHeadBiondi

The jeep was before I bought it now it's empty but I'm going to rebuild it when I get the extra cash

Fred/N0AZZ

Hell even with amps and subs a large battery bank is required to call for that much power. Then he says the someone else runs 3 big alt's must be subs, amps, multi battries and huge hydraulics for those big jumps

BassHeadBiondi

No just about 70k watts in amps.

salad

The XJ power system is regulated as one entire unit. The system "somehow knows when it's full" is because a voltage regulator compares to battery voltage at a very high rate. If you're measuring 14.4V across the battery terminals with a multimeter while the engine is running, this means that regulation is working properly. This explains why the PCM still works and battery hasn't exploded in your face.

If your gauges inside the cab don't match the real numbers you get from a concrete test then your gauges are the problem - usually a ****ty ground is the culprit of this.

ehall

Its not possible to get 14v and 18v at the same time on these harnesses unless its wired up totally wrong.

Alternator is supposed to connect directly to battery, then chain out to the PDC and starter and whatnot from there. Alternator power fluctuates so you are supposed to use the battery as a cushion float. That single link also gives you a single place to put a heavy fuse, so you can protect everything from overloads.

If that's how yours is still wired up then you are getting bad readings. Otherwise the wiring probably needs to be corrected.

How is it wired up?