Need help - electrical issue (long post)

I have a stereo system with the following equipment: - PPI Art Series A1200 powering 3 JL Audio 12W3v2-D6's - (2) PPI Art Series A600.2's powering Boston Acoustics    components front and rear - Phenix Gold MBS 100 Battery Separator (not isolator) - Phoenix Gold VB 200 Circuit Breaker near front battery - 2nd Battery in trunk ('regular' 900 CCA battery) - Power Acoustiks 1.2F capacitor (sometimes a Phoenix Gold XSC12 1.2F capacitor) - 2 gauge power cable from front to rear battery - 2 gauge ground from chassis to rear battery All amps are connected directly to the second battery or capacitor in the rear. The amps are only 2-3 feet away. Here's the issue: the second battery gets completely drained after about 3 weeks of listening to the stereo at moderate levels - I'll play it loud for maybe one or two songs at a time. The primary battery is never harmed. Looking at the volt meter on the capacitor, the voltage will fluctuate between 10.9 and 13.6 volts when the music is loud with lots of bass. After the second battery gets totally discharged and can longer hold a charge, the system will cut out as I bring the car to a stop. Then, the sound will return about 5 seconds after I leave from a stop (assumingly from the rise in RPMs). During the 'pause' in music, the volt meter will read about 6.9 volts, then it jumps up to about 13 volts or so after that 5 second period. Also, once I remove the totally drained battery, thus leaving no battery in the rear, the system behaves in the same 'pause' and 'resume' manner. As soon as I put in a new 'regular' battery the system plays normal again with no pauses. That lasts for another 3 weeks or so, and the cycle repeats. I know about the Big 3, but I definitely don't believe that the amps are starving for current based on the rate they completely discharge the second battery. I am going to replace the Power Acoustiks capacitor with a Phoenix Gold XSC-12 1.2F capacitor. I know caps have been debated many times and I do not want to get into a debate. I will definitely use a cap. I noticed a marked difference in sound quality and volume just by simply switching back and forth between the Power Acoustiks and Phoenix Gold caps - the system sounded much better with the Phoenix Gold. My lights never, ever dim, even on the deepest bass notes with all lights and accessories on - even if I remove the rear battery (and the car is moving). Here are my questions: 1.) Should I remove the battery separator and run the power and ground directly from the front battery to the rear (with a fuse or circuit breaker in-line)? 2.) It appears that the front battery and alternator have nothing to do with the stereo - is the battery separator saving my alternator and primary battery? 2.) I'm going to install 3 BatCap 800's plus the Phoenix Gold cap - should they help this issue? 3.) The Phoenix Gold capacitor has a 20/25V surge rating. Exactly what does that mean? 4.) Should I run the ground directly from the front battery to the rear? Any other suggestions are greatly appreciated. Thanks in advance for your assistance.

No, my alt is not upgraded - it's the stock 90 amp. I don't get any dimming; my primary battery never gets drained. I've reasearched the capacitor issue far too many times - I'm sticking with my real world results - I'm going to use a quality capacitor. Thanks for your help. Anyone else with suggestions.

What are your real world results?

aez-you posted your real world results....and the results are problems due to insufficient power production.  Alpine and dwarren are right, you need more power generation, not storage.  That first, then take the isolator/separator out of the way between the two batteries.  I would connect everything up sans caps, and get it all perfect.  Then, if you wish, add the batcap.

This is why I ALWAYS RECOMMEND AGAINST AN ISOLATOR!!! Get rid of that thing, upgrade your alternator, replace BOTH batteries with a pair of identical batteries, wire them in parallel, and go with it... The cap is neither here nor there. It, in and of itself, will NOT cause any of the problems you are describing. Leave it in the system, or take it out... but take the suggestions I have made above, and I can almost promise you that your problems will at a minimum, be alleviated. You COULD even fix it completely, IF you upgrade your alternator and underhood power cabling far enough.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

i agree with the above advice, and would like to chime in with one comment....please take a moment to check the ground resistance of the spot that you've used as the ground for the second battery. if the resistance shows up as more than 1ohm on the dmm, then you should consider finding a better ground point. actually, it should be far less than 1ohm. please take a moment to read this: forbidden's post on groundsall problems can be resolved with a hammer

Thanks for all the replies. In the past, several people have told me to eliminate the battery separator - they say it can consume upwards of 1 volt. Is that true? Has anyone had any real world, or actual (not theoretical), experience with the BatCaps? If so, which ones and what was your opinion on them? Thanks again.

I say get off the capacitor/ BatCap way of thinking (this piece of advice coming from somebody who used to think capacitors were the ticket I needed) Everybody else here is right. The solution is merely a new alternator. While voltage isn't necessarily the thing to be looking at (amps is what you need) 10.8 volts is LOW! Typically a car runs at 14.4 volts. In my case, with a new Mean-Green 200amp alternator, with my music running at full-power, the voltage INCREASES, along with a slight RPM incrase. When running, my voltage will rise up to 15 volts, with about 140 amps at a fast idle. So here is one reason an alternator is a problem. Second, there is no plausible reason for "Better Sound Quality" from changing capacitors. A capacitor is an energy bank, storing power on demand. If your amps need the power fast, they take it from the capacitor (since it takes the alternator a few seconds longer to react to the increased current draw). They don't have anything to do with sound quality, other than giving your amplifiers a little extra "sip" of energy. Thirdly, "I know about the Big 3, but I definitely don't believe that the amps are starving for current based on the rate they completely discharge the second battery." WHAT THE HECK DO YOU MEAN?!?!   Amplifiers need current. Just because they drain a battery, doesn't mean they're not starving. I don't know what you're trying to say here, but this is what I got out of it: 'My amplifiers are easily getting they power they need because I have a battery.' A battery is just another power storage unit. In the case of a car, it is used to store power to start the engine, or run lights when the engine is off. After the engine has started, power is supplied by the alternator. Fourth, I know you don't want to argue about capacitors, but when you get your alternator, you probably wont even need them. As a matter of fact, unless you're planning on listening to your music for a while with the engine off (at say a party), you don't even need that battery. It's just holding power, not producing it. BOTTOM LINE: DUMP THE CAPS AND SECOND BATTERY (DEPENDING ON APPLICATION) AND BUY A H/O ALTERNATOR> Mean-Green Industries (Who I use) or Motor City Reman or Mechman (as suggested prior)~wayland