This is really really weird, I have upgraded the big 3 already, and just finished installing a new 150 amp alternator, now the weird thing is that during idle, the voltage on the small amp is 14.4 and the big amp is 13.8, but after a long drive and the same volume, the voltage still drops to 12.8 and 11.5!!! WTF???

It is supposed to be 70amps at idle too, I dont think the alternator is the problem though, could it be the battery you think??? Thats one of the things I have had for a long time and its just a crappy battery...I was planning on getting the SVR and a cap pretty soon though...

 

It could be. I guess the voltage would be low if the battery is not charging correctly.

 

get a red or yellow top.. a battery does matter.. if the if alternator cant charge the battery the correct way then its no good...

 

Do you guys think that maybe the grounds are bad? I had to ground them under the seatbelt bolts but I tried to scrape away all the paint, I'm pretty sure it's bare metal...Ill have to check again later on today.

 

What is the voltage at the battery? Load test the battery to see if this is the problem. My guess would be it is in your wiring somewhere, sounds like you don't have a solid connection somewhere.

 

How do I do that and what kind of tool will I need?

 

Take it to autozone. They can test the battery for you.

 

Is there a way to find out how many amps the alternator is putting out?

 

Just got back from Autozone, they said the battery was at 12.4 volts and under a load it was at 11.6 volts, and with the car on it was at 13.0 volts

But I completely forgot to have them check the alternator to see how many amps it was putting out at idle (can they check that?)

Well is that good or should it have been 14.4 with the car on?

 

Sounds like the battery is ok. The system should be at 14.4 with the car on.

 

14.4 even at the battery?

 

might not be the same thing but my car did this too, due to a mechanic's f'up. when the newer engine was dropped in, they didn't change the module along with it. I bought two new alternators until I found out what was wrong. It made the voltage all screwy.. probly not what you're lookin for but you might wanna look at it nontheless.

 

Yes even at the battery. I would recheck your wiring conections. When they load tested it did the voltage drop as the load increased (with the car on)? If so you either have something seriously hooked up wrong or the alternator is no good.

 

Is there a way they can check the alternator?

Another thing I noticed at night is at idle, the lights are normal, and when I give the throttle a little tap to like 1000rpm the lights get brighter....I havent checked the voltage yet with car moving yet...

Isn't there a way to have the alternator spin faster??? How would a UO alternator pully affect the way the alternator works?

 

the voltage at idle will always be low. The alternator isn't spinning fast enough to put out the 13.8-14.4 it should be.

 

Even thought it is supposed to put out 70amps at idle???

Well I just got back from Autozone and they checked the alternator, it wasn't charging the battery at idle, but if they gave it a [I]little [I] gas then it would go all the way to 14.4, so now I'm kinda confused as to what it could be....

Do you thing the alternator that I just got is bad? Does belt tightness have anything to do with it (mine is a little loose) ??

 

Bump your idle closer to 1k. Many alternators will cut off below a certain rpm. Maybe your car's idle is a little too low.

 

At 1000 rpm the amp goes from 11.5 volts to 13.0 volts and stays that way for the most part even at 4500 rpm.

As the car idles the voltage drops on both of my amps...I am gonna call up the alternator place on monday.

 

Is that an alterstart alternator? Maybe you can get a smaller pulley.

 

Yeah it is, I bought it from http://www.4alterstart.com

I was looking for a smaller pulley but didnt know where to look.

 

Any luck yet?

 

No not yet, I am pretty sure that there is a ground problem with the big amp though, as it is always lower than the small amp...

I did call up alterstart and they told me that with their alternators you usually give up a little bit of low end voltage and make it all back and then some when you start moving around. But I still think a smaller pulley would be extremely beneficial, as I like to play the stereo with the car running at idle (like when I play basketball and whatnot at my house)

 

11.5 Volts is not a little it's a lot.

 

Yeah but the other amp is 14.3 volts so 11.5 is a little...I'm postitive now that it is simply a grounding problem, and that the voltage charging thing will be fixed with a slightly smaller pulley

 

uh... my car NEVER sees 14.4... should I be worried? i wanna know more on this... ur using a stock battery right? check the water level?

krazy