gsean400

Need some info on the stock alternator, having a really hard time finding what I need to find. I currently have my stock alternator witch I believe is 90 amps, beefed up to what I think was a 140amp. i am having problems with the car charging during idle in DRIVE only. Interior lights will dim and if I play music long enough the stereo will cut out and I will get a battery light, once I take it out of drive and put it in neutral everything goes back to normal and it appears to be charging. The guy at the alternator shop says its because now that it is beefed up, it will produce less power at idle, and more voltage the higher the rpm. Does this sound true? I have never heard of an upgraded alternator producing less volts at idle, and I have been doing some digging on the forums, and one guy with an LS said the voltage regulators are always the culprit. That our alternators cannot be rebuilt because they use cheap voltage regulators and the machine they bench test it on will never see the voltage drop because it spins a lot faster then our 500-600 idle in drive. It seems this is the case for me since it only happens in drive.. At a low rpm. this is the third time I have had my alternator rebuilt. the point of this thread is to understand our alternators better, and if it is possible, to lead other members away from rebuilding the alternator on our car if the rebuild is really the problem here.

Also does anyone know the size of the stock alternator pulley? I am going to run a smaller pulley to up the charge in drive so it will charge like it does in park or neutral (around 850rpm) thanks

Mr Jokster

iTrader: (8)

Yes its true that some higher output alternators will put out less at idle, it all has to do with how its built. When going legit and buying a high output alt, they make both kind, those that have high output at higher rpm with less at idle and those that give higher output at idle, but less at higher rpm's. DC Power Alternators explains it, but their site is running very slow right now... At least for me it is.