The PondMAX Backup Battery is perfect for running in overcast conditions or at night.Timing function decreases the energy consumption on cloudy days or winter months. The pump works 15 minutes every hour if the timing function is enabled by placing the timer switch to "Timer On" position. The "Timer on/Timer off" switch switches the pump running mode between "intermittent mode" and "continuous mode". In the "intermittent mode" (i.e., "Timer On"), a built-in timer is enabled to run the pump 15 minutes per hour to save the energy. In the "continuous mode" mode, the built-in timer is disabled, and the pump runs continuously.