Amp is Draining my battery.

[kevinaw21892]

I have a sony xplod 1000 watt amp running a dual head unit and a 12" subwoofer. I just hooked it up the other day and I got all the wires right and I tested it and everything worked fine. I have the remote wire connected to the radio ignition fuse so it would turn off when I turn the car off. I look at the amp and the light goes off like its suppose to. About 6 hours later my car wont start. The amp had to drain the battery, but how cause it turned off. I dont know what could of happened that made it do that. Can someone help me with this problem. Thanks!!

[Perry Babin]

If you pull the fuses out of the amp, does the battery remain charged?

Did it kill the battery more than once?

Have you had the battery load tested to confirm that it's not past its prime?

[whiterabbit]

Don't trust those load tests. If it fails, your battery is REALLY dead. If it passes, the conclusions are inconclusive. I've had TWO batteries that would pass the load test but were at end of life.

Charge for hours, and I can crank the car once. Wait 15 minutes with the car off, the battery fails. Roll the window down once with the car off and the battery is dead in less than 5 minutes.

Here's what I would do. I'd start with a multimeter set to "amps" and measure the current load straight at the battery. I'm betting the load will read less than 1000 mA.

Assuming that's the case, really the big big big thing I would be looking at is the battery itself.

[TO-3]

I guess I could ask how old the battery is, for starts? I live in Phoenix, and because the heat is hard on the batteries, they usually only last about a year and a half to 2 years. The problem could also be related to the deck. Are they (deck and amp) both connected to the same point for the sense? Usually there is a separate output to control peripherals.

[Perry Babin]

If a load test is done properly, it should show if the battery is good or bad. There are several testers. One has a simple fixed resistive element. It's the most common tester but isn't accurate on all batteries. There's also a tester (link below) that uses a carbon pile (variable resistor) that you set for the battery you're testing. It draws more from larger batteries for more accurate results. The proper load test would have drawn more (1/2 cca rating for 15 seconds) than starting the car and rolling the windows down and would have shown that the battery was no longer up to capacity.


http://www.harborfreight.com/cpi/cta...emnumber=91129

[whiterabbit]

Easily possible that either the equipment was a poor product or the tech was not using proper equipment properly. I just took the battery into a Kragen and asked for a load test. passed twice.

But for me, that brings up a question. If either of those scenarios are possible, how can I trust any result generated from a random autoparts shop? The implication is ultimately the same as I originally suggested. A failure is a failure, and a pass is inconclusive.