Damn, Alternator Not Enough?
 

I think Im loading my alternator too much. I have a Fiero GT Electric fan, a walbro reired fuel pump and a massive 2000watt stereo system with pre-amp and all. My battery slowly but surely dies out, even if my car is still on. My voltometer shows that when the stereo cranks and the a/c is on, it never goes past 11v on idle and while driving at around 12, If I really turn up my system it will reach almost 9v and shut off the radio by itself. Basically I have to have my foot on the gas pedal accelerating it to about 1.5k in order for it to not shut off. Its my alternator isnt it?

Sounds like you need more AMPs than the alternator can supply. Had that problem too. 100 AMP FD alternator solved that problem for me.

I was getting only 11.4V at idle and maybe 12.5V at cruise...not nearly enough to charge the battery. You should be seeing 13.8-14.4V or so, AFAIK.

Turn all your loads off (including the fan) and check your voltage at the battery posts with the car running at idle (750 rpm's at least)...What do you get? Should be at least 14.4v...

I feel sorry for that poor little alternator...And your eardrums, lol :)

Note poor grounds could also cause your problems...

A regrounding and an FD alt upgrade is in order. I have not done the regrounding, but I have the FD alt with a perma cool 16" fan, 400W power inverter running my laptop and a wideband, and I see 14.4 at idle with the fan and the inverter running. At night, I see about 14.1 with the lights, defrost, radio, fan, and power inverter all going.

yea it definitly just sounds like your draining more power then what the alt can put back in the battery just get a fd alt and reground and that will solve it for sure

thanks everyone, Thats what Ill do. Any grounding writeups as to the key spots?

https://www.rx7club.com/2nd-gen-archive-72/grounding-how-thorough-discriptive-199558/


That's the one in the archive, I pretty much followed it the way it shows to.

The stock piece of shit alternator cannot handle the load.
Grounding will not fix your problem.
These cars don't need to stinkin' 2000W stereo in them. :D
I get my audio fix revving the engine.

Get an FD alternator.
This is probably your easiest and quickest fix.


-Ted

!Amen to that!

My stereo includes and mp3 cd player and 2 rear stock speakers, no fronts :D

You may also want to get the fd alt. rewound for better performance since you have a big system in that 7.

Thats quite a strain you've got on your electrical system.

Yeah, these FD Alternator Alternators kick ass. :D

West TX RX-7 purchased an FD Alternator Kit from me. He couldn't have been more pleased. He needed it because he was running 2k watts rms on his stereo.

sounds great, how much are your alternator kits?