I have a weird audio problem! Anyone ever have this happen?
 

I just had my alpine/polk audio system installed the other day. 4 new speakers, 3 8"s in a custom box in the rear with an alpine 300 watt amp, alpine MP3/CD head unit. Now I had a Clarion system before that was ripped out and stolen, but almost all the wiring was left in tact except for the antenna wire. We get everything hooked up, sounds great! The next day, my PFC commander reads 12.5 volts instead of the usual 13.8-14.1. I thought that was odd, then it started dropping a little more and all the check engine lights come on. But my temps were fine, I was loosing power from the battery. The next morning I drive to work, about 28 miles, and it goes all the way down to 10.7. I get to work and pull the positive wire off the battery for the sub/amp and the battery recharges, it's not the alternator. When I play jazz, i.e. no sub, the car stays around 13.5. So why is the sub killing the link between my alternator and battery when it gets a signal??? I'm dumbfounded! Or just plain dumb...any advice would be great!

What kind of Alpine amp do you have? And only 300W? :confused: Hmmm, off the top of my head it sounds like you have a big current draw from the amp that's not allowing the battery to be charged, or it may be a bad alternator too. Do your lights dim w/ heavy bass hits? Are you running a full-size battery or one of those mini kits? You could try running a cap, or using a thicker power/ground.

check the cable to the altenator, and every link from it along the way.

IMO, it's the altenaor

The car was running fine before I put the subs in. I have an underdrive pulley on the alternator. Today, the volts decreased slowly like the other day, even though I had the stereo off for a while. This afternoon, started the car, still only about 11.5 volts, then shut it off, took off the positive lead completely, started the car, same voltage. Then, I drove a little bit, turned the stereo ON, and it jumped to 13.4 volts. So, I'm kinda confused. Maybe it's how the pos. cable is connected at the battery, underdrive pulley, or I do need a short c. Thanks for your advice.

was the battery fully charged before install???

are u running capacitors??

Try this......

Unhook the amp power wire at the battery......Measure the voltage at the battery, then start the car and measure the voltage again.......let the car idle and turn on all the accessories, air on high, headlights on high, fog lights on, interior lights on........then monitor the voltage for a few min.......If the voltage drops like it has before its not likely the stereo.......Have the alternator checked....

I'm not running capacitors, but that was suggested to me by an audio engineer. This shitty problem is forever changing. I started the car, air on, radar detector, but no stereo. 13.9-14.1 volts for about 5 minutes. Then, turned on the stereo, instant jump down to about 12.7 stayed there for a bit then slowly decreased. So I shut off the stereo, after about 5 minutes it was back up to 13.8.
Maybe I should try a small capacitor or what Keith suggested. It's a great sounding system, too bad it's draining my battery! Thanks for all your suggestions, I do appreciate it.

is it the stock batter???

try ungrading to a yellow top optima batt

thATs wut i have and i have a big system also

no battery drainage either

mike

When you're turning the stereo on......are you turning it up real loud or just letting it idle?

It sounds like the stereo is pulling enough current to knock the alternator output down to the float voltage of the battery. I can see that happening with a big system, but not with 300 watts.

I had this problem before. The alternator can't support the load, making it work harder. This doesn't allow the battery to fully charge making it worst with time. You will end up replacing both. You should find an alternator shop that will rebuilt your and upgrade it as well, then get a optima battery.

:werd:

on a side note, the reason it may jump after driving for a little is because when the rpm's go up, the alternator's spinning faster and making a little more voltage i guess, so while you're giving it gas/driving it will stay a little higher than at idle

my S4 is the same way, with headlights on, and stereo full, and with brake applied i get like 12.5v on my voltmeter, with everything off i get around 14

good luck

Its a stock battery, from Sears, not a dry cell or anything. Fairly new, in the last year. I didn't turn the stereo on loud with pounding bass, just a normal level, and it did jump down. But now, I find that if I run the car for a bit, then turn on the stereo, it minimizes, or lengthens the time I have until it starts diminishing.
Do you think a small capacitor would help, or is that just avoiding the main problem? If it fixes it, fine, I'll get it. But I don't want to get it and then have it just lengthen the time until my battery keeps discharging. Personally I think that underdrive pulley is affecting it a little.

A cap wont help your problem....it wont hurt either.

If you have been reading the the voltage off of the PFC.......you need to use a good volt meter and read the voltage at the alternator output and at the battery. Compare that to what the PFC says.......

Eliminate as many unknows as you can. Use the car for a whole day with the stereo UNHOOKED not just off. If you still have problems then its not the stereo.