M4 Sealed Lead Acid Battery (12 VOLT 8 AH AGM) For M4 $24.99 + Shipping
This workhorse battery provides enough power to pump up to 200 gallons per charge. Four hours continuous use. Does not need to be charged during the average working day. No memory effect - 300% more energy per dollar than lithium or NIMH batteries. Changing batteries only takes a few seconds via M4 battery door.