fhukingviet

Recently, i got a stereo setup, jl 500/1 and a 10inch jl w6 subwoofer, lately when i come back to my car, the starter would crank slow as hell but would eventually fireup, is my amp staying on when my car is off or whats going on? would a capacitor or a bettery battery fix this?

nsxxtreme

Start the car remove the battery cable if the car dies your alternator is toast. If it stays running then your battery is probably shot.

The only other way to test is it take is somewhere and have it load tested. Or go buy a load tester from harbor frieght they aren't very expensive.

mrdeadman

Check to make sure your amp isn't staying on.
You can get your battery and alt tested for free at most auto parts stores.
Or if you want to do it yourself, you can also put a charger on the battery. If it takes a charge and holds it your battery is fine and your alternator is shot (unless you have significant parasitic drain).
How old is the battery?
They usually last about 5 or 6 years.

ken9

Might be some wire's connected that draining your battery. I didn't think that small stereo would drain you stock electrical so eazy unless some where in the install wasn't correct. Did you install this?

pegasus75

I agree with Ken9, the current system load that you have right now is not that big, and shouldn't cause any problem, unless there is something wrong with the installation. My next guess will be your alternator.

suspendedHatch

DO NOT do this. Very bad for your car. Your battery is like a filter for the mess that is produced by the alternator.

$20 multimeter from Sears. Check the battery voltage. It should be around 11 volts. Start the car and check the battery voltage. It should be 14 volts. If it's not, then your alternator isn't charging your battery. If it is, then pull your battery and take it for a free load test at the parts store.

nsxxtreme

It wont hurt anything its been done thousands of times before me. A volt meter wont show much of anything unless you alternator is 100% dead. An alternator that produces 10 amps will still put out 14 volts. And if your battery is even half good it will supply the rest of the current. Even a battery that is measured shortly after turning the car off will read higher then 13V. By disconnecting the battery you are placing the load 100% on the alternator. If its weak it will fail.

Its not the best test but its something that can easily be done at home. The better solution as I mentioned was to go get the entire system load tested not just your battery.