At this time, there are three popular battery technologies; these are lead acid (PbA), Nickel Metal Hydride (NiMH), and Lithium (Li) Batteries.  Each of these are discussed below.
 
Lead Acid

Lead Acid batteries are the most common type of battery; they have been used for the last hundred years.  The industry is mature.  Lead acid batteries are the most recycled commodity with about 97% of batteries being recycled.1  This compares to only 55% of aluminium cans.
 
Batteries for on-road EV use are made as 6V, 8V, and 12V batteries.  This allows one to choose different batteries for the same voltage.  For example, you can use 12-12V batteries, 18-8V batteries, or 24-6V batteries in order to have a 144V system.  The limitation is the space available and the payload capacity of the vehicle to be converted.     
 
The advantage of PbA batteries is:

The disadvantages are:
 

 
The good news is that this industry is developing Advanced Lead Acid Batteries.  For example, East Penn Manufacturing Co. (www.eastpenn-deka.com) recently announced an "Ultra-battery" which combined lead acid batteries with super-capacitors in a single unit.  They stated that this design quadruples battery life while improving power density by 50%. This pairing is 70% cheaper than NiMH batteries.

 
Nickel Metal Hydride (NiMH)

NiMH was the best new battery technology a few years ago; but recently have there has been little coverage in NiMH development.  We believe that NiMH batteries may be better than Lithium in the long term because of the availability and lower cost of the materials and the reactive nature of Lithium.  
 
 
Lithium Batteries

At this time, we do not recommend Lithium Batteries. They are light-weight, but they can be expensive ($20,000).  The major reasons, EVA does not recommend Lithium batteries are because:

Our objective is to protect the consumer.

     1Battery Council International