There are many variables that determine how long battery backup can be maintained. An inverter-powered battery backup will provide AC power to a conventional submersible sump pump during a power outage. For an inverter-powered battery backup which will maintain the operation of your main sump pump there are 3 main factors to consider:

  • The power consumption (or more importantly the current consumption of the sump pump.
  • The capacity (in amp-hours) of the battery or battery bank.
  • The duty cycle of operation, i.e. the ratio of the on time to the off time in the pumping cycle.
  • For example, if the pump works for 10 seconds and is then of for 100 seconds, the duty cycle is 10/100 or 10%.

Let’s use the Run-Time Calculator to illustrate and example of a battery with 100 amp hours of operation. with a pump with 6 running amps that comes on for 10 seconds every 5 minutes. By inputting in those values we see that this situation will yield approximately 51 hours of run time.

In order to obtain a quantitative estimate of the battery backup time of an inverter powered system: Click here for a runtime calculator

As far as the pump is concerned, for a given water pumping capacity, the less electrical current the pump draws, the less power will be drawn from the battery bank and the longer the system will function. Therefore, the user should strive to implement an efficient pump.

The greater the battery bank capacity, the longer will be the backup time during which the system will function.

The greater the pumping duty cycle, the less time the system will function.