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Evaluation of Battery Pump Performance

When examining pump performance it is first important to understand that while a manufacturer may claim that a pump can pump 100 gallons per minute (gpm) it doesn't mean that it will pump that much water when installed. How much water is pumped depends not only on the pump, but also on the installation in your particular sump.  How high the water must be lifted to get out of your house (static head), and how much resistance there is in the discharge line (dynamic head) control how much water you can pump.  Adding the static and dynamic head together gives the total head, measured in feet of water.  Typically for a residential sump pump the total head will be in the range of 10 - 15 feet.  When looking at pump manufacturers stated flow, you should look at the values for 10 to 15 feet of head to determine how much water will be pumped by the installed pump.

Pump curves are used to determine more precisely how much water an installed pump will move.  The following figure illustrates this for a typical installation where the water must be lifted 8 ft and pumped through a 1-1/2 inch diameter discharge line.  The green line represents the total head as a function of flow.  The yellow and brown lines represent two different pumps.  Where the pump lines cross the green line is where that particular pump would operate.  This shows the yellow pump, a typical 1/2 horsepower primary pump, would pump about 50 gpm.  The brown pump, a battery operated backup pump, would pump only about 35 gpm.  This illustrates the performance gap between a typical primary pump and a battery backup pump.

 Figure 1: Primary and Battery Pump Performance Comparison

Conclusion: Battery pump does not pump as much as your primary AC powered pump, when you need it most.

To address the performance gap between the primary and battery backup pump, we install a high capacity 3/4 horsepower AC backup pump powered from a voltage inverter, the Deluge Pump.  The voltage inverter takes DC power from 12V batteries and turns it into AC power, like you would get from any electric outlet in your home.  Figure 2 illustrates the substantial improvement in performance with the Deluge Pump, which pumps approximately 72 gpm.

 Figure 2: Deluge Pump Performance

Conclusion: Inverter powered deluge pump gives backup capacity significantly greater than that of the primary pump.

Last modified: 05/22/08