Battery selection is key for any electric car conversion, in order to get the most efficiency. You can't use just ordinary starter batteries, like what's in your gas powered car right now. They are not designed for long high current discharges. Deep cycle batteries are the type you will need to use, as they can put out high current for an extended amount of time. The most used battery for an electric car is the lead acid battery, which breaks down into three major types.

1. Flooded battery

2. Gel batteries

3. AGM batteries

The Flooded or "wet" cell is by far the most available lead acid battery. If they are the type with removable caps, then you have to periodically check and refill the cells. All batteries will produce hydrogen and oxygen when recharging, and you will lose a certain amount of water during this process unless the battery is of the sealed type ( maintenance free) The benefits of using this type of battery is usually the cost, they are the least expensive. They are also less sensitive to overcharging as compared to the other types of cells. However they can also be prone to collecting deposits on the plates if they are left in a discharged state for extended periods. This is called sulphanation, due to the sulphate crystal deposits that can form on the plates. There are devices known as"desulphators" which as their name implies can eliminate the deposits and basically rejuvenate an old battery back to usable condition. The flooded battery must also be kept charged up. A deep discharge without a quick recharge will cause the battery to lose its capacity. Flooded cells will perform best if the discharge is kept to only about 50 saturation. Since the acid is contained in the mat,leakage is not a factor. This is also a sealed battery, so you don't have to periodically check the level of the cells. The hydrogen and oxygen produced when charging, get recombined back into water during the charge, so this battery is very efficient. Any conventional lead acid battery charger will work with this battery, and the AGM batteries have a real low self-discharge rate, so they can sustain a charge even with no charging for a long period of time. Really the only dis-advantage to this battery is the price. A typical GEl battery is 2-3 times expensive than a flooded battery.

Your choice of the electric car conversion whether it is DC or AC, is going to be the deciding factor in your battery choice. If you choose to do a DC conversion you will want to use the 6 volt battery to make up your battery pack, simply because they provide the most amps for the size and weight. If you go with an AC conversion, you will want to use the 12 volt battery, as you need the extra voltage to make up the higher voltage requirement of the controller. Which ever voltage type you choose, the flooded lead acid is the best choice from a cost/power ratio. As battery technology continues to progress however, you could soon see the day when AGM batteries becomes as cost effective as the traditional flooded lead acid battery.