The AH or amp hour rating should be a minimum of 105-120AH. Some battery manufacturers also rate their battery in CCA or Cold Cranking Amps while others will simply rate them in amps. While this can all get pretty confusing, I would also recommend a minimum 60-75 amps or 600-700 CCA base on how your battery is rated. Also, please note that you should use a 12V Deep Cycle Battery and NOT an automotive battery. Deep Cycle batteries are designed to run your pumps for a certain time frame based on your pump's amp draw, your total head and the discharge diameter whereas automotive batteries are designed more for the starting or surge power for engines and pumps and NOT for the sustained running of an engine or pump. While they will work, they will NOT run your pump nearly as long as a deep cycle battery will.