There are many types of batteries available, of course – which one is right for you? For audio installations, experience has shown that the best results will be obtained using deep-cycle marine batteries. These batteries can be obtained from almost any dealer for approximately $60. Lead-acid batteries are preferred over calcium-based (maintenance-free) batteries because of their superior internal characteristics. Maintenance-free batteries are usually designed to provide a large amount of current for a short period of time. This is great for starting your car, but not so great for running a high-powered system. Deep-cycle marine batteries, on the other hand, are designed to provide a moderate-to-large amount of current over a long period of time. The plates in each cell are thicker, and they are made for deep, cyclic use. This is important because you can severely drain this type of battery without damaging it, which is ideal for car audio installations. There are three ratings you should check out when selecting a battery. The first is the CCA (cold-cranking amps) rating. This indicates a batterys ability to provide a large amount of current for a short period of time at cold temperatures. (If youre looking for a battery that will be used just to start your car, this is the rating you would be most interested in.) The second rating, and the one that is most important in terms of your system, is the AH (amp/hour) rating. This rating simply states how much current the battery is capable of delivering for a period of time. The larger the rating, the better. Typical deep-cycle marine batteries have AH ratings of 85 to 105. The third rating you should look at is reserve time. Deep-cycle marine batteries really shine here. Reserve time represents the batterys ability to recover and produce electrical energy after a discharge cycle – without re-charging. The longer the reserve time, the better. Installing the extra battery or batteries in parallel will result in the most efficient use of its (their) power. When using this method of connection, your total AH rating is the sum of the AH ratings of all of your batteries. Note that batteries installed in this manner should be identical (the same make and model). If theyre not the same, their internal impedances will differ and, eventually, one battery will discharge the other. When wiring the electrical system, dont skimp on large-gauge wire. Welding cable is preferable because of its tough outer jacket, fine wire strands, and good flexibility. The bottom line is that you should never use less than No. 4 wire. Also, dont forget to install 150-amp circuit breakers at each end of the power cable running from the front to the rear of the car. The circuit breakers will protect the vehicle in case of a short somewhere along the length of the cable. Its important to take the time to plan out your electrical system. A properly designed and installed system will provide a good foundation for your auto sound components while maintaining reliability and safety. The audibly superior performance will be well worth the added time and expense.