It contains two universal #1290 9AH batteries with F2 connectors. The batteries are taped together side by side with the terminals in a vertical straight line so that the positive terminal of one is at the bottom left position, the - to + shunt connects the two middle terminals, and the negative terminal is at the top position. Be sure and write down the names of the connectors that the battery cables connect to on the board before you remove the batteries. There are two possibilities for both the positive and negative terminals.