NO CAPS!!!! just upgrade to a good dry cell or gel cell battery. Bigger then usual. The JL Slash amps, 1000/1, has a regulated circuitry that no matter if you are running at 12 volts or 14.4 volts, It will put out the same power. But if you are just running a lead/acid battery, you may put more strain on it over time. Especially if it is weak already. I would recommend a Kinetik 1800.
Here is a calculator the will help you out. >>>http://www.kinetikaudio.com/calc.asp
Just play with it and it will help you. If you click that you are replacing the starting battery then it will say to install to batteries. One in under the hood and one near the amp. But if you click that you arent replacing the starting battery then it will say which one to put near the amp.
The reason I say to use the 1800 is to compensate for not using one in the back.
Here is the specs on the 1800>>> http://www.kinetikaudio.com/hc1800.asp
Yes it is a lil pricey but it is worth it. I had 2 of them in my caprice as well as an upgraded high output alternator. Not a single light dim or voltage drop.