Audio Electrical Trouble

I have an 88 IROC with the following audio setup: the audio system power cable feeds a Tsunami capacitor which in turn feeds a Kicker 650 watt amp. The amp feeds two 6 x 9s in the sail panels and two subs in a box on which the capacitor and amp are mounted.

I have had problems with my battery losing its juice. Initially, the battery would die overnight. It would go from 12 volts to almost no voltage in this time period. The battery is good according to Advance Auto Parts tester. I haven't really done anything to correct the problem except attempt to diagnose, but now something different happens. Over the past week or so, over 48 hours, the voltage will drop to about 11.75 V but the amps drop enough that I can't crank the car over to start it.

The readings with my multimeter have seemed to be quite random and haven't allowed me to pinpoint anything, but today I went to work and recorded some data. I arrived at the warehouse where my car is and measured the battery voltage. It was 11.67 V. However, the car did not have enough amps to start up. I jumped the car and got it running. I ran the car for a while. Immediately after turning the car off, I unhooked the positive battery cable and the audio power cable and hooked my multimeter between the positive battery terminal and the pos. battery cable and audio power cable. I read a little over 1 amp of draw. I removed the audio power cable from this system and the amp draw was now only 70 to 80 mA. I immediately hooked the audio power cable back in line and the amp draw went up but to much less than the 1 amp draw I had gotten less than a minute earlier on the initial reading with it hooked up. Of course, when the capacitor lights and voltage display shuts off a short while later, the amp draw decreases again but not to the 70/80 mA without the audio sys. hooked up.

So I ran the engine again for about 5 to 10 minutes. Immediately after running, I measured the amp draw(audio system included): 450 mA. I let the capacitor shut down and the amp draw was 190 mA. I unhooked the audio power line and the amp draw was 70 mA. I immediately hooked the audio power line back up and now the amp draw was only 330 mA (capacitor lit up) and 140 mA once the capacitor shut down.

I ran the engine again, probably a little longer than the previous trial. A little while later, I measured the amp draw(audio system included): 850 mA. I let the capacitor shut down and the amp draw was 350 mA. I unhooked the audio power line and the amp draw was 70 to 80 mA. I immediately hooked the audio power line back up and now the amp draw was only 400 mA (capacitor lit up) and 170 mA once the capacitor shut down.

I also at one point measured the amp draw shortly after running the engine. Then I immediately unhooked the audio power line (I didn't wait for the capacitor to shut down) and then less than 30 seconds later hooked the audio power line back in. The amp draw had decreased significantly, yet all i did was unhook the audio line and then hook it back up.

To me, it doesn't make sense that every time the amp draw of the audio system is different, even after the capacitor has shut off. It also doesn't make sense that if I unhook the audio power line and within 45 seconds hook it back up, the amp draw of the audio system changes significantly. I think this has to do with my battering dying, I'm just not sure how to proceed.

have the battery load tested..this determines how much current the Battery can output..should be over 500 amps but the tester will show this info and using the battery specs determine if it is good..the alternators get damaged with these hi powered audio amps..with the engine running at normal temp amplifier off,,, what is the voltage at the battery..?


leakage current should be around 10 - 80 MA...450 MA is to high...alternator diodes can do this also..the filter capacitor that the amp uses may have leakage..with the capactor removed from the amp circuit apply 12volts to the cap. it should not draw any current after it charges up to the 12 volts..if it does have a current flow the cap has leakage and is therefore n/g..

I had the battery load tested last week and it seems to be good. With the car running and the the audio off, the voltage at the battery is anywhere between 14.5 to 15 volts, so I think the alternator is working ok. Also, I doubt its an alternator diode because when I take the audio system out of the loop, the entire car only draws 70 mV at rest. I will disconnect the amp from the capacitor and check the amp draw of the capacitor tomorrow (that is what you mean right? just leave only the capacitor hooked up and test it?). Thanks for your help.

I had the battery load tested last week and it seems to be good. With the car running and the the audio off, the voltage at the battery is anywhere between 14.5 to 15 volts, so I think the alternator is working ok. Also, I doubt its an alternator diode because when I take the audio system out of the loop, the entire car only draws 70 mV at rest. I will disconnect the amp from the capacitor and check the amp draw of the capacitor tomorrow (that is what you mean right? just leave only the capacitor hooked up and test it?). Thanks for your help.

yes, remove the capacitor from the amp circuit...with the capacitor negative connected to the carbody ground see if the capacitor has current flow with the 12 volts applied..after the initial charge the cap should not continue to draw current..

when your vehicle is hot check the voltage at the battery ..it should be with 90 deg f temps at 13.75volts.........not 14.5-15 volts.

alternators can fail when the diodes get shorted from high loading with the amp power required..on engine shut down this then drains the battery...the alternator has many diodes so you can get some charging even if a diode is with leakage current ...., as it begins to completely short out.

Sorry, the 14.5 to 15 volts is when the car is running. I did some more testing today. First I removed the capacitor and the amp from the audio power line but left the line itself hooked to the battery to check for any shorts in it. The amp draw was only 70 to 80 mA, which is what it is when the audio power line is not hooked up. I then hooked up just the capacitor and there was additional amp draw above the 70 to 80 mA even after the capacitor seemed to have equalized with the battery voltage and the digital display and lights on it shut off. I then hooked the amp up along with the capacitor and this did not increase the amp draw over what it was when just the capacitor was hooked up. I checked the grounds and they seem to be good. This makes me think there is something wrong with the capacitor and that it has a leak somewhere.

test the caPACitor after it has been in operation with the amplifier for like a half hour with a good amount of audio power...this will get the capacitor warmed up..see what LEAKAGE current you get...

the voltage at the battery with ENGINE ON AND RUNNING AT NORMAL OPERATING TEMP SHOULD BE 13.75VOLTS DC ..........



the battery voltage with a good battery which has been at rest for an hour or longer , that the ENGINE HAS NOT BEEN RUNNING,,, should read about 12.85 volts dc..

If the battery reads 11.25volts then you have a bad cell in the battery..

THE ONLY TIME you will get 15volts at the battery is if your in 20 degf temps at first starting the engine at the battery...I assume your in palm beach where its 90 deg f now....

I may be wrong but from what I have read about GM CS130 alternators is that the voltage limit on them is set at 14.8 volts, so this led me to believe my readings in the 14.7 volt range are ok.

I may be wrong but from what I have read about GM CS130 alternators is that the voltage limit on them is set at 14.8 volts, so this led me to believe my readings in the 14.7 volt range are ok.



yes you are wrong .. the voltage output of an alternator is controlled by the built in regulator. when this is cold the voltage will be higher ..When hot the voltage will drop. the normal output on a heated alternator that has been operating for about an hour should be 13.5-14.25 volts...if the air temp is 90 deg f this will be 13.5-13.75 volts.


If the air temp is 20 deg f the voltage would be 14volts to 14.25 volts.


the maximum output voltage is 15volts but you live in antactica ?

because that is how you could normally see this high end of 15 volts..

if you now are getting 15 volts on the battery with the engine running get another meter to confirm then have the alternator tested.

remove alternator so it can be tested..autozone has a tester to check these out....