When to Upgrade Alternator

[proto_mkiii]

So I finally decided to get rid of my AFM after going through several and unsolved mysteries involving them. I went ahead and and bought a vpc and intalled it and all seemed right with the world finally. Then night time rolled around and when I turn on my headlights the car starts sputtering when I try to give it gas. If I leave the car on for much longer the idle starts to bounce. The next day I try to drive again with no issue. I had my lady watch the voltage on my SAFCII to see what it looks like. 13.6v at idle and when I pick up it goes up to 13.8v and then drops again. Today I decided to turn on my ac to see how that changes things and voltage drops to something like 11.5v. and the idle goes nuts. So I'm trying to figure out what I should do for my voltage drop.

If it helps I'll list my electronics I have hooked up:
Boost Gauge (not sure if that drains much power)
SAFC II
Greddy Turbo Timer
Innovate MTX-L wideband
and now the VPC

I was going to install my PRofec Bspec 2 but I need to figure this out first. I was looking at the alternator on driftmotion but I'm not sure if thats what I need. Any ideas.

 

[Poodles]

None of those items should be pulling that much draw unless you have a power issue to start with (or you have more than that, say like e-fans?).

Check grounds and battery connections.

Could also be where you wired in those items.

 

[IBoughtASupra]

I second poodles on the ground issues. Check the body ground by the driver side fender by the battery and make sure it is clean. Do the same for the wire going to the engine block.

 

[Dan_Gyoba]

I'll third that.

It would probably be worth having your battery load tested. Most places that sell batteries will do that for free, a battery with a dead cell will drop voltage like that under load sometimes, but a bad ground is far more likely, if you ask me.

I'm running a stereo with a lot of draw, and can get by on the stock alternator just fine. I used to have an upgraded alternator when I was competing in IASCA, but I'm not doing that anymore, so I just replaced with stock when the upgraded one died.

I get a consistant 13.8V for my ECU and ignition system even with the stereo on at moderate-loud, the headlights on, fogs, and heater on high with the stock alternator, everywhere from idle to 5000+ RPM. (It will start to drop after about 3-5 minutes at a 600RPM idle with everything on, but it's a gradual drop, since the alternator is not able to provide all that current at idle speeds.)