I would look at buying a deep cycle battery vs a standard car battery. The main difference is:

A car's battery is designed to provide a very large amount of current for a short period of time

A deep cycle battery is designed to provide a steady amount of current over a long period of time.

A deep cycle battery can provide a surge when needed, but nothing like the surge a car battery can. A deep cycle battery is also designed to be deeply discharged over and over again (something that would ruin a car battery very quickly). To accomplish this, a deep cycle battery uses thicker plates.

Once you have decided what type of battery to purchase. You next need to pick the right sized battery. This will be mostly dictated by the location that holds the battery. Measure the width, length and height of the storage area and pick a battery that will fit into that area.

The third consideration of the battery is how long it is designed to last. You will see batteries with 36 month, 48 month, 60 month and even some 84 month guarantees. The long the life the more they cost.