I really don't think you need a 2nd battery unless you are playing for extended periods of time with the car off (car shows). I'm pretty sure I remember hearing that adding a second battery is worse because the alternator is trying to charge both batteries and not one. An "Optima" battery is a deep cycle battery that can handle high amperage much better than a regular car battery can. If you live in a cold weather climate the yellow tops also do not suffer from low temperature ailments like regular old car batteries do.

 

i'm going to run the ground from the batt terminal and get the install looked at on monday.

 

I also think your ground should be 3 feet long or less, the less resistance the better.

 

it is now although it's only like 4 or 8 guage wire. I had an idea to run it from the neg terminal on the battery with 0 guage. i'm just pretty unhappy with my system right now.

 

I have one in the trunk to one side and a 20 farad capacitor on the other side. You wouldn't need a big battery like the one under your hood. Stinger (and other companies) make smaller batteries that can fit in tight places. http://www.stingerelectronics.com/we.../batteries.asp

 

If your system is set up on an independant loop with your other battery, how do you go abouts charging it? Do you have to take the battery out each time and charge it? Because if your alternator is charging it, then its not independant of the main electrical system, and you haven't done anything other than add to the time you can play your system with the car off. The cap may have helped slightly, but most likely your system didn't need the second battery in the first place

 

Upgrade your ground wire to 0 awg, and do the BIG 3 before purchasing a new alternator. That may solve your problem, but I suspect that there won't be any way around your problem other than getting a new alt or downgrading your equipment

 

should i ground it to the batt terminal or to my current ground point?

 

It's a mgic battery in a magic car. No, really, I think it has isolaters to keep the rest of the system from using the charge from the dedicated battery. I will ask my stereo guy what they did next time I talk to him because I don't know exactly what they did but I can't argue with the results. I don't want to turn this guy's thread into a technical battle of which way is better. I'm just offering an alternative solution. It works for my setup and thought it might be an answer for his problems. The setup I have now is the only big setup I have ever had that didn't bow to dimming lights & a fluctuating idle.

 

Add a second battery! Trust me you need it. It doesn't have to be isolated from the main battery. Whether you isolate it or not NEVER play your system at moderate volumes for any extended period of time with the car off. When the voltage falls your class-d amp can fail. Believe me I know quite a bit about this subject.

 

Did you have problems before you installed the second battery or did you have everything installed at the same time. I've been into car audio for a long time, and the consensus within the community is that extra batteries are for extended play only, doesn't help when the car is on because the alternator supplies a higher voltage than the battery and is thus the limiting factor neglecting resistance. I think you misunderstood what they meant when they were talking to you about isolating the extra battery. An isolator's purpose is to prevent your system from running down both batteries when the car is off so it won't start. The isolator only allows you to run down your extra battery when the car is off, but when the car is on has no affect since the alternator is powering your system

 

I had the whole setup installed at once. I think I'm clear on the isolator's position and I am aware of what the community has to say about additional batterys. How can I argue with what I actually have and have had in other cars? I have heard all the replies from "the community" telling me it's, theoretically, not the right way but this is the way it was setup and it works.

 

It works but you may have never had a problem in the first place. The capacitor could be doing most of the work in stabilizing your voltage since you stated you had a 20 farad cap. Even that would only make a slight difference. Try removing the extra battery and seeing if you have any problems. I'd bet nothing would happen, because it isn't possible to defy the laws of physics.

 

I'm not claiming to defy physics, just claiming it works the way it's setup. In fact works better than any other setup I have ever had. I hae a very similar setup in my Armada, (2) JL 12w6's, MB Quartz comps, Zapco, 20 farad cap, 1000/1 amp & a 300/4 amp. It fluctuates in rpm's and has dimming lights too. They only real difference is 1 less battery. Now how do I argue with that?

 

There are more variables than just an extra battery, its a whole different car which means different electrical load on the system, different grounds, different alt etc. Take out your second battery and report back. I'll bet you won't have any light dimming etc. Shouldn't take more than 5 mins to disconnect your bat and then drive around for 20 mins testing and report back.