i have a 94 se bonneville when car gets warm i notice the volt guage start to drop also, i have a terrible miss when trying to go up a hill or trying to pass. the alt is new from advanced autoparts and i had it checked. everthing is new and no ses light. thanks

1) Specifically what readings are you seeing?

2) Who checked it, and how?

3) What were the circumstances behind getting that new alternator?

4) Have you checked all battery cables at _both_ ends for clean, solid connections?

Bonnevilles have a reputation for eating their alternators, and your rebuilt one may be a bit flaky or just not holding up under the load, plus your battery cables may not be properly delivering additional backup juice from the battery at times when your alternator is maxed-out under high load.

14 volts at alt connections all good i saw a bulletin in all data that states: customer complaints low volt with accesories on the say to chang alt to 140 amp but it does not state about when hot its the third alt i have had in this car

You cannot spend enough money on an alt for a Bonneville. An alt will also kill a battery, and a battery can kill an alt. If you can afford to, it'* best to change them as pairs, especially if your battery is more than 2 years old.

www.domesticperformance.com has great alternators. 160 or 200 amp (160 should be fine for you) with beefed up internals and bearings. The rear bearing on the stock alternators is prone to premature failure.

I noticed the same thing happens on my 88 and my dads 93 bonneville. I asked him about it (he is an Electrical Engineer) and he siad it was nothing to worry about. Apparently in the voltage regulators on the alts, theres a temperature sensitive componment (likely a resistor) that will lower the output voltage once it is warm. so when the engine is started, it gets charged more quickly, becuase of a higher voltage coming from the alt. then once the engine is warm, likely the battery is charged by then and the regulator will bring it down to 13.8 or so.

we had a problem a few years back where after the car has been warm for awhile, and the voltage would drop. Turns out that there was a problem with the belt.