sidewayz_FC

well here my problem, i just put a replacement alternator and battery in s4, thinking it would fix the problem with my stereo. when im at a stop light, no accessories on other then my stereo, the battery will drain. im running a mono 1000 watt amp with a 1200 american pro 12 (with a gigantic magnet.) it will drain the battery and shut off at stop lights. my question is what should i do to make it stop doing this, its ran with 8 guage wire straight to the battery. help me get back to bumpin the gangsta musiz y0


i had the same setup in my accord last year and it didnt do any of this stuff.

RotaMan99

Well, considering the S4 electrical system is already stressed, especially when you put on the brakes, you have about 10amps worth of lighting at the rear at. At idle, the alternator does not charge at its full potensial.

You may want to upgrade to a FD 100amp alternator, or bring your alternator to a specialty shop that can rebuilt it for more amp output.

For a temp solution, you could try raising your idle a bit to spin the alt faster and see if that works.

FYI. A 1000watt amp is about 76amps at 13v at full power. Thats not including the ineficiency of the amplifier. S4 alternators are 70amps. So you have no way of winning with a stock S4 alt at idle and barely while driving. You would have to go 100amp or above.

sidewayz_FC

yeah i figured, even just listening to the stereo loud (without amp) will make it cut out and all that garbage. Ill hafta search around about the fd alternator, is a bolt up deal?

RotaMan99

Its almost a direct bolt in. You will need to get a dual belt pulley for the FD alt shaft, I think banziracing makes them. You will as need to get a diff bolt and nut for the adjustment arm portion and run one new wire form the battery to one of the terminals.

Before getting one and installing one, search the forum for FD alternator or something similar and you will find some threads with good information in them.

Only at stops? Is the amp ON and just turned down or is it completly off. Either way it shouldn't take that much power. I have bad luck with Reman alts, they either work, or they don't.

I bought my FD alt for about $230 at Advance Auto parts and got the lifetime warrenty .