Capacitor drain battery?

[SamE30e]

Hey,

I installed a 12" MTX sub and 900watt MTX Thunder Amp along with a Capacitor. Before all this my car would start fine, no problems, since I put the stereo in the battery voltage drops to about 10.8 volts after a day or two and will crank slowly and not start.

After putting a charger on the battery for about 10 minutes it starts right up.

Could the Capacitor be draining the battery?

Also I know the amp is not doing it because when the car is off it is off.

Thanks

Sam

[AndrewBird]

A capacitor wouldn't drain the battery. Once it's fully charged, it acts like an open circuit and would pull any amperage unless it was shorting and draining on something. More likely you have a short or ground issue that is draining it. Check all the connections. If you can't find anything wrong, start unhooking components until the drain stops.

[TwoJ's]

Yeah, exactly what he said. It's likely that you've got a short somewhere with something you did while hooking everything up. Is the amp new? It's unlikely, but there's a small possibility that there's an open circuit internally causing this to happen.

Have you tried disconnecting the amp and seeing if that changes anything? Have you metered the battery while the car is running to see if you're getting sufficient charge? I guess there's a possibility that you killed the alternator with the new install (not likely though).

If all else fails, do what Nitro suggested and start disconnecting things until the draw dissapears.

[SamE30e]

While it is running the car is making between 14.3 and 14.7 volts. I'll try disconnecting the amp.

[AndrewBird]

Those are good numbers for a working alternator. Start disconnecting stuff.

And a little note. Be careful about driving the car with a very dead battery. A battery that is super dead will put extra load on the alternator and can fry it. You should always re-charge a dead battery out of the car with a charger before putting it back in the car.

[SamE30e]

I'll try that. I think my battery is toast though, it's a Optima Redtop that I got out of the returns pile at wal-mart for free, it worked fine in the warm, but I noticed in the cold it didn't have as much energy. I'll try a different battery. Man why am I so cheap.

[abepark]

I had an old audi that bugged the shit out of me as well after I installed only some boxed 6x9's I swear is had to be the stero cause before I touched anything it worked fine. now I did a battery test like yours and the numbers were fine....thats where the trick was

you know how to test for a draw? well start pulling fuses, I did that and found no draw...that really confused me until an older tech told me your alternator can actually make a draw on the battery.


now tests for draws and see which circuit is pulling the power gives you a good sense of where to start digging

[europeanplates]

Most likely your battery was getting tired and this extra load has put it to it end.

Tyler

[SamE30e]

Fixed... Just needed a good charge.