alternater question

I have a 88 jeep 4.0 wagoneer and i had the battery die on me three times already. It only has happened on the highway after about two hours of driving.I got the alternater and the battery checked and the alternater is fine but the battery was bad. I had just got the battery about three months ago. What happens is the amp gauge inside of the jeep drops down and then goes back up to 14. can anyone help me figure out this problem.

I thought you said the battery was bad?

yea but i replaced it with another one and the problem is still occuring. the amp meter still jumps from red line to 14. I replaced the battery connections and cleaned the ground but still happening.

1st...Its a voltage gauge...not amps.

With that out of the way, sounds like a possable short somewhere. As you are not blowing fuses, I would double check all the cables from the battery for any loose insulation or rubbing against the body.

Rev

Had a similar issue last month. Turned out to be a little 14-16ga green wire coming off the alternator. It had rubbed against something or caught on something and was frayed nearly apart. 2 second fix and about 5 cents for the but connector.

Check the wiring first, since it is quite possible either to chafe and short or to corrode or to become fouled with oil, etc. If wiring appears all right, and mileage on alternator is high, it's also possible that either the brushes are going bad or the sliprings are dirty, or both. The early stages of brush failure will sometimes be intermittent and hard to catch.

Thanx guys for all your help im going to look at what yall mentioned and get back to you. If I still cant figure it out.