As window cleaners, we depend on our equipment working so we can make money. It is important to know how we can care for our leisure batteries so they keep on working and let us keep on cleaning. We will discuss some of the most important questions in this article.
How much electricity do I use?
The answer depends on many things. How many of you are working from one battery? Do you have powered hose reels? What is your flow rate? How many hours do you work in a day? Do you do lots of small jobs or a few large jobs?
Calculations
We have tried to calculate the draw on our battery in a day. We mostly do very compact, residential work. Here are our calculations:
We run 2 x shurflo pumps at 80 on a v16 flow controller.
In 1 minute that uses 2.4 litres of water.
On average we use 550 litres of water in a day.
550/2.4 = 229 Therefore on an average day we can assume that we power the pumps for 229 minutes or just under 4 hours.
This is shocking when you consider that there are two of us working for 8 hours. So in 16 man-hours, the pump runs for less than 1/4 of that time!
The pump is rated at 8 amps, and because we run it at 80 on the v16 lets assume it draws 80% of maximum. Therefore the actual current draw is 6.4 amps.
To keep it simple we will say the pump runs for 4 hours at 6.4 amps. Thereby taking a total draw for two men for the day to 25.6 ah.
We also have two powered hose reels. On average we clean 15 houses a day, so the hose reels wind in 15 times each, a total of 30 times.
The time to reel in the full 100m of the hose is under 30 seconds. Even if we take the maximum time every time, it is still only a total of 15 minutes.
The hose reels draw under 40 amps. Therefore at the end of the day, they have taken a maximum of 10 ah from the battery.
Conclusion
We have tried to err on the side of caution and over-estimated where possible. Of course, we are not allowing for a split charger or a b2b charger in these sums. According to our calculations at the end of the day, we have taken a total of 35.6 ah from our leisure battery.
The less a leisure battery discharges the more cycles it can do, but to avoid damaging a lead-acid battery it should never go below 50% of full charge.
Also, note that the ah capacity on a battery is measured at 25 degrees. Battery capacity decreases as the temperature drops. In fact, at 0 degrees a battery loses 20% of its capacity.
In addition, batteries lose capacity as they age.
If we had a 70ah battery, every average day we worked would use 50.9% of the charge. If working at 0 degrees at the end of the day there would be just 20.4ah left in the 70ah capacity battery. This would obviously result in the battery failing ahead of time and costing more money to replace it.
Likewise, if we had a 110ah battery that we did not charge for 2 days, we would be 65% discharged by the end of the two days (even more in the winter).
Also worth remembering is that we have taken our average days. That means that there are days we use more electricity than we have assumed here.
Hopefully, this exercise shows the importance of taking care of our leisure batteries. Firstly buy a battery with a large enough capacity for the work you will be doing. Secondly, fully charge your battery regularly to keep it working optimally and lasting a long time.
We recommend Exide Dual batteries. They are perfect for a window cleaner’s needs. They are “dual” in the sense that they are both good as a leisure battery with a long and slow discharge, but they also have cranking amps, the ability to provide more power when needed.
This makes them optimum for running a low powered 12v water pump for long periods of time, but also for using a powered electric hose reel that will require a short burst of power.
They are readily available on Amazon. See the 115ah version below.
