battery light?

sn95 bullitt · Dec 6, 2012

My battery light came on and my auto meter gauge is reading at 12amps. The battery is only 3 months old. I let it sit in the driveway running and amps did not rise. What should i check?

joekd · Dec 6, 2012

I assume you mean 12 volts, not amps. Check your terminals and all connections but I think a new alt is in your future. That should jump to 14V as soon as the car is started.

CC'S95GT · Dec 6, 2012

does the volt guage move at all when you rev the engine?
do you have underdrive pullies?
Like stated above, volt output should always be over 14vdc reguardless of the RPM's

joekd · Dec 6, 2012

If you have a multimeter (which everyone should) check the volt + right at the alt connector, this will give you proof it's the alt or something else

97FloridaGT · Dec 6, 2012

What year is the car? I agree that most likely it's the alternator.

ttocs · Dec 6, 2012

could also be a bad battery that will no longer charge. Go to vatozone and get the alt/batt tested.

sn95 bullitt · Dec 6, 2012

Lol i know that about the amps. I drove 400 miles yesterday and 10 miles before i pull in my drive way the battery light came on.

So all night my car alarm was chirping funny but when i started it this morning battery read at almost 15 volts when its running. I put my alternator test on and it read 14.0v. Running. I didn't charge the battery are anything.

97FloridaGT · Dec 6, 2012

Bad voltage regulator in the alternator. Time for a new alternator.

MustangChris · Dec 7, 2012

^ good suggestion Junior.

I suggest finding a buddy with the same car and swap on the alternator. As long as its not a 03/04 cobra it shouldnt be too difficult. lol.

underdrive pullies, voltage regulator, alternator, slipping belt, bad battery, low water in battery, corroded connections, bad wiring, etc. etc. etc.

start with the battery.
Is it spewing junk from under the caps? (if it is, the alt is going out.)
is the water low? (if it is, replace it with *distilled water* only.)
are the terminals clean?
are both the cables clean, in tact, etc?

then move to the alternator. swap it out. that will give you an opportunity to inspect the belt. it also rules out the alternator, voltage regulator, and pulley.

(i wouldnt suggest buying a new alternator, just yet.)

sn95 bullitt · Dec 7, 2012

Everything looks good. New belt. I took the car over to the auto parts store where i got the battery and they ran there test and the alt was 14.5 volts. Battery was 14+ also. How would i go about checking the UD pulleys? Also this afternoon my abs light was coming on with the hids. Maybe there's a problem with the his relay.

ttocs · Dec 7, 2012

put the old ones back is the only way to test it, they are probably why your alt is failing. When they slow down the alt they make it work harder, which generates more heat while its ability to cool has been comprimised because its turning slower. You have probably developed some bad solder joint on the rectifier diodes in the voltage regulator so that when the heat/cooling cycle gets to the right point it no longer makes contact.

sn95 bullitt · Dec 30, 2012

So its happen a few more times now. I have figured out it something with the hids. The battery light comes and if i turn the headlights off then the battery light goes off and the volt gauge goes back up to 14. I never had this problem before i put the HID relays in. Could it be the relays?

BigBore96 · Dec 30, 2012

sn95 gt said:
So its happen a few more times now. I have figured out it something with the hids. The battery light comes and if i turn the headlights off then the battery light goes off and the volt gauge goes back up to 14. I never had this problem before i put the HID relays in. Could it be the relays?

If you've checked everything else and it all checked out and you didn't notice the problem until the HIDs I'd definitely look into that. It's more than possible to be causing your problem

CC'S95GT · Dec 30, 2012

make sure your ground connections are paint free and tight.

ttocs · Dec 30, 2012

HID's actually draw less current then the standard halogen lights but the amperage as the ballast charges will change which could be causing the problem. When you first turn on an hid it will draw 10-12 amps of current and then after a few secs it does down from 7-9 amps. A standard halogens current draw never changes so the ECU might be seeing the change in current draw as meaning the alt is not supplying as much current as it was. Another possibility is that the ballasts also tend to set off our abs lights dependind on where the ballasts are mounted. I am not sure if that is the change in curren draw or if its some kind of EMF getting emitted from the ballasts that the abs sensor is picking up or what but often by just moving the ballast that problem can be fixed. You might try to move you ballast and see if it changes things. I have heard that if you put them inside the engine bay, not infront of the header panel, that there is less problems with the abs light. I mounted my head/fog ballasts behind the battery and under the CAI.

sn95 bullitt · Dec 30, 2012

Ttocs

I was having that problem with the abs light. So after i posted a thread here i was told yo by hid relays. So i did and this is my problem now. Should i remove the relays?

http://sn95forums.com/showthread.php?52930-abs-light

sn95 bullitt · Jan 13, 2013

Well the alternator went out tonight.

chrisv_10 · Jan 13, 2013

I have a alternator for sale. A reman that is pretty new about a year old from autozone. I have no use for it since I'm 4v now so I'll let it go cheap. Just have to figure out shipping. You probably can't wait that long, but let me know if you decide to buy mine.