wbacall

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!

wbacall

Anybody?

camarozz95

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.

Angelis83LT

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.

97lt1fanatic

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.

wbacall

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

97lt1fanatic

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

shoebox

Not on my car (with stock alt).