For example, a battery with 120 minute RC will have approximately 72 Ampere Hours. This means that the battery should produce one amp for 72 hours of continuos use. More RC is better in every case. To increase RC, connect two six volt batteries in series or more 12 volt batteries of the same type in parallel. To increase the voltage connect two or more in series.
Sealed batteries require less preventative maintenance.
Deep cycle and marine batteries are designed for prolonged discharges at lower amperage. A deep cycle battery will typically outlast two to four car batteries used in deep cycle applications. A car battery is used to start the engine and deep cycle battery is to supply power to the accessories. When purchasing a isolator, be sure that it matches your alternator or charging system. There are many other types of batteries.