1G 1G Quick alternator question...

[GooeyGus]

So I am having (what I think is) a weird symptom. I was measuring my voltage the other day while the car was running, and I'm getting about 13.5 at the battery. So, thats fairly normal. I know DSM alternators suck.

Here's the strange part... I measured voltage at the output on the alternator itself and I'm reading 15V... so just to recap, 15V at the output screw on the alternator yet only 13.5V at the battery. Is something weird here or is this normal?

I am by no means a 'noob' when it comes to cars, but I dont think I've ever had a car where the voltage at the battery differed from the alternator while the car was running.

I guess I should also note that I've gone through about 4 alternators in the last 5 years (three of them were in a two month period...) but this one I've had for a while and it seems fine.

The reason I mentioned that is because with one of my failures, the alternator started making some crazy voltages. My dash lights got about as bright as the sun for a minute or so before it died (luckily I didn't fry the ECU) but when this happened my alternator fuse got super hot and melty. The crazy part is that the fuse did NOT blow. Now, I know I need to get a new alt. fuse, but do you think it could be contributing to this weird voltage differential?

I did a search and couldn't really find an answer....

 

[6bolt2gdsm]

It sounds like a voltage regulator problem on the alternator that made your lights go real bright. If the voltage is different from the alternator output to the battery, then that sounds like high resistance. You aren't gettin these alternators from advanced auto are you?? They aren't really known for have the best electrical parts.

 

[GooeyGus]

It sounds like a voltage regulator problem on the alternator that made your lights go real bright. If the voltage is different from the alternator output to the battery, then that sounds like high resistance. You aren't gettin these alternators from advanced auto are you?? They aren't really known for have the best electrical parts.

I got it from schucks, basically the same thing. I'm doing the saturn alternator swap as soon as this one kicks the bucket.

Yes before it had a regulator issue and the alternator died, but this one seems fine, yet I am getting different voltages.

When the previous alternator blew, the fuse got so hot that it melted itself, as well as the corner of the fuse box which it sits in, so I have no idea why it didn't blow. Could a melted/messed up alternator fuse cause the differences in voltage?

 

[6bolt2gdsm]

When the previous alternator blew, the fuse got so hot that it melted itself, as well as the corner of the fuse box which it sits in, so I have no idea why it didn't blow. Could a melted/messed up alternator fuse cause the differences in voltage?

Yea that could be the problem. If the fuse is melted enough it will cause high resistance in the circuit. Is it the original fuse, or the right amperage its supposed to be?

 

[GooeyGus]

Yea that could be the problem. If the fuse is melted enough it will cause high resistance in the circuit. Is it the original fuse, or the right amperage its supposed to be?

No idea if it is original or not, and i cant even read the amperage because the cover is melted

 

[6bolt2gdsm]

That could be your problem right there, especially if the fuse is higher than specified. That would cuase your wires to burn up before that fuse blows.

 

[cincinnati4g]

My talon shell's alternator fuse was straight melted through the fuse block when i first got her so i just replaced the whole harness because i didnt feel like dealing with it all. Could have messed up a lot of things such as the wires that are ran to that particular fuse in the panel or just made high resistance for themselves somehow and shorted.

 

[RoryBarron]

15v at the alternator and 13.5 at the battery is normal

 

[JStoops]

the right amp for the stock alt fuse for a 1990 is 80A

 

[Boosted3s]

yeah< you will get some lose through the wire due to resistance.