Battery Discharge Rate

The diagram above is for illustration purposes. It shows how a leisure battery could discharge over a working period. Note that voltage and amps are steady for up to two hours. We see a fall off in the 2 - 4 hours range and after 6 hours the voltage fall off is dramatic.

1. Operating at maximum a 100psi 5.2 LPM pump is capable of drawing 9 amps an hour.

Most leisure battery manufacturers recommend that you should not use more than 50% of a battery's capacity on a regular basis. Continually draining a battery below 50% of its capacity then recharging will affect the cells' ability to hold a charge.

As the cells degrade, the less time it will take to use 50% of the capacity. By capacity, I refer to the current draw from the battery (amps): as the pump draws current the amps held in the battery fall as do the volts. The lower the volts the greater the drain of amps from the battery.

2. What does this mean in real terms? The following figures are based on running a single pump with no form of controller.

A 75 amp hour battery could be at 50% of capacity in 4.5 hours. Or a 120 AH battery in 7 hours (Red and Green)

3, Using a pump controller can reduce the current draw from the battery, extending the working time per charge.  For example, if we reduce the current draw to 3 amps ( the average draw with a controller flow rate between 60 - 70), a 75 AH battery could take up to 10 hours to be discharged by 50%; and A 120 AH battery could take up to 12 plus hours to be reduced to 50% capacity (Blue and Yellow)

Note: If two pumps are used the current drawn is doubled, eg up to 18 amps an hour if running without a controller, or 6 amps in point 3.

Some leisure batteries can be drained to 80% of  capacity occasionally. However continued use in this way will shorten the life of the battery. Follow the manufacturer's guidelines. Use of a pump controller could extend the use per charge of your WFP system when compared to a system with no controller. All our controllers are fitted with a voltmeter and battery management.

Note: The diagram above is for illustrative purposes, Actual discharge rates will vary system to system and are dependent on battery condition, water flow rates and other factors. While a controller will allow you to work longer per charge, the amount of time will vary.

Also see:

Battery Basics:

What is Volt drop

Bat Is displayed