The recommended battery is the
Wayne WSB1275 - Maintenance Free AGM Backup Sump Pump Battery (75 Amps) for the Wayne WSS30V - 1/2 HP Combination Primary and Backup Sump Pump System, however most any 12V, deep cycle, maintenance free AGM battery will work in the 75 amp or 100AH (amp hour) rating. The oversize battery case (included) will accommodate a 12-volt SLA battery (up to a 27-frame size).
Be certain that the area around the batteries is well ventilated. Before servicing the batteries, blow away gasses by waving a piece of cardboard near the batteries.
The control box has a DC charger designed to shorten the recharging time of your battery, and to prevent overcharging. In addition, the control box has
a time delay which keeps the pump from repeated, short cycles when it shuts off. The time delay feature will allow the pump to run 20-25 seconds after the switch reaches the off position.
The main pump suction on this pump is actually just above the base where the line of square holes surround that bottom section of the pump. This is what's known as a top-suction and will help prevent clogging of debris that might normally clog a bottom suction pump.
The backup pump is activated by a separate float switch that is set to activate a few inches higher than the main pump float switch.
Since most backup pumps are operating on DC 12V power, they do not have any HP rating. Rather, they are rated in GPH (gallons per hour). The backup pump in this system can pump a healthy 2300GPH at a 10 foot head which rivals many standard 1/3HP 120V operated primary or main sump pumps.
If the main pump should fail, it is recommended that you replace it with another
Wayne CDU800 - 1/2 HP Cast Iron Submersible Sump Pump w/ Vertical Float Switch since all the piping and included check valve is already setup for that pump.
Of course, if you should decide to go with another pump, you could always separate the two pumps at a later date and go with the pump of your preference.
I would also suggest reading the WSS30V
INSTALLATION MANUAL for more information on how this system operates and is installed.
If you have any other questions, please let me know.