WaterSecure Battery Audit

The WaterSecure system uses a battery bank to power AC well pumps and other appliances. Using the following calculations, we can estimate the overall size of potential battery power on a full charge. Taking the battery voltage and multiplying it by amp hours (Ah) equals watt hours (Wh). Once we have Wh, the next step is to reduce that number by 50%. This is non-usable energy that is lost in the inverting process. It also helps roughly account for other external factors such as temperature and battery age. Our final value of Wh can then be used and divided by the total wattage of all the combined loads. 

Calculating Wh example:

A WS6k-800 comes with 8 batteries that are 12V and 55ah. On a full charge we can estimate 

12V x 55ah x 8 batteries = 5280Wh

5280Wh 2 = 2640Wh

Next, we can roughly estimate the cost of wattage per hour on our appliances and well pumps. On appliances they will come with a sticker that states the wattage. 

When it comes to calculating the wattage of a single phase AC well pump, use the following estimation:

Horsepower x 750w x 1.5 Power Factor = Pump wattage

For example, a 1.5HP AC motor would take

1.5 x 750w x 1.5 Power Factor = 1687.2w 

Finally each of our appliances and well pumps have a starting wattage that is much higher than the running wattage. Usually, the necessary starting wattage will be around 2 times the running wattage but will only apply briefly in the initial start up. It is difficult to plug in starting wattage into our equations for runtime but it is important to take account for the momentary increased wattage. In order to avoid an overload fault on the WaterSecure 3k/6k/12k, make sure the total starting watts and running watts do not exceed the rated power output for the water secure. The 3k maxes out at 3000kw, 6k maxes out at 6000kw, and the 12k maxes out at 12000kw.

Putting it all together, we can go back to the example of using a WS6k-800 with a well pump and an appliance: 

1.5HP Well pump only with running watts of 1687.2w per hour

Battery bank charged comes to 2640wh

2640wh 1687.2w = 1.56 hours of runtime approximately 

This does not take into account the power coming in from the solar panels but it gives us a rough estimate of runtime. 

Makita appliance only with running watts of 460w per hour

Battery bank charged comes to 2640wh

2640wh 460w = 5.73 hours of runtime approximately  

Same as before, with the well pump this does not take into account any power coming from the solar panels. Also note that neither of these loads, separate or combined,  have a total starting wattage that goes over 6k. Combining the two we get the following calculation: 

Makita appliance and 1.5HP well pump with a combined running watts of 2167.2w

Battery bank charged comes to 2640wh

2640hw 2167.2w = 1.21 hour of runtime approximately 

Using these calculations you can gain a rough estimate of battery only runtimes with your Watersecure unit.