Thread: Alternator Overcharge?

I was headed home after work today when I heard the alert ding, and looked at the DIC to see "Charging System Failure"

First thought was alternator was dying, so I reach up and switched the DIC to voltage to see it at 15.3, then it almost immediately dropped to normal range. I kept it on voltage the rest of the way home and it was contantly in the normal range, never going above 14.44.

Was the overcharge a fluke? I searched but most results were about low voltage. Anyone else ever encounter this? Is this possibly a sign of impending doom for the alt?

ive had 2 new reman alts over charge right out of the box, and my truck didn't seem to like running like that.

Well it only overcharged for 5 to 10 seconds. It hasn't happened since then. I went to the store just a little while ago and it was fine.

I am just going to have to keep an eye on it for awhile.

Just an update.

I checked the terminals and the positive terminal had a good bit of corrosion on it. I took both terminals off and cleaned them up really well after work. The whole trip to work and home from work (25 miles each way) it never got above 14.5.

I'll keep an eye on it and post up if it happens again. If it does happen again I have a feeling it might end up being the battery due to some research I have been doing.

Now I have a new problem though too. I'll do some searching and make a post related to it if I don't find what I am looking for.

It is impossible for your battery to cause an over charge.

From what I have been reading (and it makes perfect sense), if there is a bad/failing cell it can make the alt think it needs to put out more volatage then is actually needed.

Gm alts are know for over charging for no reason at all. Measure voltage of your batter should be 12.6ish fully charged. Each cell is 2.3v and an auto batter is 6 cells.

All that has been said is great, but I want to you a question. Do you have anything directly wired to the battery negative post? I did once, and it gave me a similar warning after a bit of driving. What messed me up is the warning didn’t activate immediately. Anyway if you have an amp or HIDs hooked up to the battery you need to run the negative wire through the amp meter located beside the battery.