I have what I consider to be a pretty large audio system for my car.

Here are the specs:
(2) Rockford Fosgate P6002 amps
[rated at 600w RMS x 1 @4ohm - 1800w max]

(1) Rockford Fosgate P4004 amp
[rated at 50w RMS x 4 @4ohm - 1200w max]

(2) Power Acoustik FUBR12 subs - Dual 2ohm voice coils
[rated at 700w RMS up to 1800w]

(1) Rockford Fosgate 1Farad cap

My question is, would it be a wise investment to add a second battery with an isolator and an upgraded alternator or just an upgraded alternator and the stock battery or will my stock setup handle all that power with just the cap?

Thanks for your help in advance

 

i dont know what an isolator is.

If you add a second battery, use a marine battery. I think thats what they are called. Anyway, the regular batteries has chemicals or something that is not good for the interior of the car. Bad thing is these batteries aren't that powerful, but better than a cap. If you have a second battery, you won't need a cap.

I think it would be a good idea for a second battery and at least a 140A alternator for your setup. I'd try it with the 1F cap first though.

And dont go deaf. I used to have (2) 150W RMS subs and i could feel my eardrums ripping. Seems like you have a very powerful setup, just be careful and take it easy with it on your ears.

 

You shouldn't need a second battery for your set up. The RMS is what the amps will generally be pushing. Although they do have a high peek power, they won't be running like that all the time, and your cap should take care of those peek power needs. A bigger alternator if anything would be of use. Besides another battery will add extra pounds. One simple way of checking is turn all electronics on (brights, hazards, Fan, Dome light, Defrosters, anything else i'm forgetting) and thump the stereo as loud as you think you ever would. Then see if the lights dim very much. This will put the max possible load on the alternator/battery, and you can see how it holds up.

By the way I like the set up

 

You should be OK with the right alternator. If you don't already have the 140A alt. the next time yours dies I'd up grade to the 140A. Don't bother with a cap, if you electrical system is up to the challenge you wouldn't need one. Dual batteries wouldn't heart anything. Look at solenoid isolation. But you shouldn't need it.