how to wire two batteries and a cap

Cap goes directly before the amplifier you're using for the sub.  If both batteries were the same type and age you could wire them in parallel without an isolator between.  But when using one new and the other older you should isolate them for longest-lasting battery life.  Lowest cost solution is to use two new batteries that are identical and use the older battery for another car.  Battery - battery - cap - amplifier.  Ground everything to chassis for negative return and upgrade the front battery-to-chassis cable to at least the gauge of the power wire.  Fuses go at the front battery and just before the rear battery, then fuse after the rear battery as well.  Fuse size is determined by wire gauge. Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

It won't matter, as your batteries are different types of batteries. To be done correctly, they need to be THE SAME battery, not just the same CCAs. It CAN be done with different battery types, but you MUST use an isolator, and I am VERY STRONGLY AGAINST isolators. Get rid of the old battery, wire all three in parallel, and be done with it.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."

ok wat if i use the ol batterie for just temporary and the cap must be before the amp  right i was thinkin to put the cap before the secon batterie cuz the batterie is going to discharge andcharge again wit the amp so the cap have the abillity to discharge faster than a batterie and i think that will make my second batterie run wit out a problemslilrob

Just a thought....the caps and batteries will do you no good but to kill your alternator faster if it is not properly upgraded.    What size alternator do you have? 2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR

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