I am having a problem with my 94 Z28 charging system & I am beginning to suspect that Bosch rebuilt alternators are not very good. The alternator (140 amp) has been replaced 2 times. The battery is a fairly new Optima and tested good. The battery cables are new. Stock pulleys.
The problem I am having is the voltage at idle drops to 11-11'5 volts.
The car is warmed up and the Idle is at 600 RPM
Stock pulleys
The AC & lights are on.
The voltmeter reads low in the red
The voltage at the battery is 11-11.5 at idle, lights are dim & turn signal slows down.
If I raise the idle just 100 RPM the voltage goes up to normal.
I contacted Bosch and they said it was normal??
Has anybody seen similar problem with Bosch alternator?
Any other ideas?
Thanks!

 

Anybody?

 

ehh same thing with me I get the rebuilds from autozone they crap out after about a year I got tired of it and just bought a new one been fine since.

 

the stock alterntor does not charge at idle speed really. at least not at an efficient charge. The reason is simple. how long does a car sit at idle during a drive cycle? not very much. So they basically start a little above idle. All the Alts I have had do that for some reason.

 

i cant say much about bosh i have an o'reilly brand new one but ya i lost an alternator plug driving home one night and it did excatly what u are saying but with much worse effects. but it sounds like the alternator is ****, i'd take it out and take it up to o'riellys i know they can test the alternator by itself. the test's with it in the car arent as accurate, but it's worth a shot.

 

Is this true? Does everyone see their volt meter drop into the red when the car is hot and the lights are on?

 

no my voltometer is reading about 14 its a little high but nothing serious thats after its warm and lights are on.

 

Not on my car (with stock alt).