UPDATE: Fixed the problem, turn out it was the kill switch alternator post (couldn't handle the current). Better switch ordered

I need some here. Last week my battery and brake light lit up as I give it gas pass 1500 rpm and goes away when I push the clutch in. My voltmeter gauge (hooked to the radio unit power) only showing 12V while running and drop slowly to 8. The car wouldn't start then.
Took it to a shop and it showing the alternator is not charging. We changed the alt to a 90 Amp (biggest one they have without ordering an aftermarket) and put in a Optima RedTop.
Now when I turn on the car (without starting) the meter show 12V, start the car and the meter drop to 11V (I drove it around for 5 miles and it stays there, but somehow jump to 13V momentarily). So it looks like it holding charges but the battery and brake light still lit up and flickering when I'm on the gas.
If anyone had this problem and had it fixed, please share your story and solution. Thanks.
Our next step is gonna be replacing the pulley with a different one so it will jump the alt Amp up to ~120. If that don't work, I might have to order an aftermarket one. If so, how many Amp should I get?
Also, would this be an electrical problem? I have the car for 3 months now, put in ign, acc switches and push start button (with proper relays and fuses as I'm slowly turning the car into a track car) for a month and it only start this last week.

 

Is the alternator remanufactured? If it is, its possible that its going out again. I would also double check all your connections that you added just incase something is loose. Sounds like it could be a ground thats loose. Check all the connections on the battery/alternator too.

 

Thanks. I'll check all the wiring and see.

 

In a previous car I had the brake light come on and flicker from the alternator overvolting to 15-16V or something. Someone correct me if I'm wrong, but I thought 12-14V was normal though, so 13V shouldn't have been a problem? Try hooking your multimeter up directly to the battery maybe and see if you get a more radical reading? There might be a decent amount of voltage drop to the radio wiring.

 

Weird thing is when they hook up the voltmeter to the battery terminals, the needle doesn't go into the charging zone at all. Do you think 90Amp is not strong enough to keep the system charge? My car is just an RS with ~370 hp, stock stereo system with a Alpine head unit, 3 gauges and push start button, that's all.

 

Is the alternator new or remanufactured?

 

remanufactured. 1st one didn't charge so I replaced the stock battery (liquid is black) with a Optima RedTop then put in another alternator. So 2 has been put in.

 

Bump

 

it is most likely the alt fuse on the positive terminal of the battery cable. that is the connection between alt and battery. the brake and battery light signals a charging system error. if u got new alt then its the fuse.

 

I checked the fuse, it's still in 1 piece but the middle looks burnt (ti burnt color) and I don't remember what it looks like when I put it in so I thought the fuse is fine. I'll replace it with a better one anyway just to be sure. Thanks

 

more amps you can get the better. Im sure later on down the road, you might add things that might suck that up ex. stereo, gauges, boost controller, 50w hid's, electric fans.

 

In my experience, remanufactured alternators are crap. They are not built to the same specs as OEM. They rely on the lifetime warranty to cover this. Either rebuild the original one or buy a new one.

If you are getting the battery light on, then the rectifier circuit is probably going bad on the alternator. Basically, the alternator is failing. You should get 13.8 volts while the car is running.

 

How many amp does the OEM alternator have?

 

i am in the same position you are in lol i switched my batteries and got the light shortly after, i can't remember how it looked prior either so i am just replacing it.

 

Did you get it fix?