2nd Battery

I am planning on getting an optima yellow top as a 2nd battery and I need to know how should I go about installing it. I already have a dry cell battery under my hood running through a 300 amp fuse to my 2.4 farad capacitor, to my distribution block (which also has 2 150 amp fuses), and to both of my amps. Can I just take the main power wire off from the battery to the capacitor and put the battery in there and then run it from the new battery to the capacitor? Should I put in another fuse in between the new battery and the one under the hood? Or do I even need another fuse?

Short and simple answer is... buy an isolator and a sealed battery. Two of the most popular types of sealed batteries are Gel Cell and Coil. Optima makes good sealed batteries. The reason for a sealed battery vs. a regular battery is that most people install the second battery inside the vehicle. Non-sealed batteries can emit hazardous fumes if they develope a leak or tip over (not to mention the battery acid that can get into your vehicle).

The isolator is installed between the alternator and the 2 batteries. It acts as a brain, and determines which battery needs the charge, and routes the power accordingly. Isolators come with installation instructions for the wiring to the batteries, but you will need to know which wire to disconnect from the alternator to the stock battery and then reroute it to the isolator.

never wire them (batteries) in parallel, unless they are the EXACT same make and model, and installed at the same time. Even then, you still shoudn'd do it. If one battery is weaker, or older older than the second one you put in, it will drain current from it. They equal out eventually, but still, it isn't a good idea. The Isolator, and sealed battery is the best way.