RVIA Show, New Product Introduction
One subject that will always create a lot of conversation on the various RV forums is when someone asks about running their air conditioner via an invertor, powered by batteries. The educated consensus is typically that you can probably do it, but the energy storage capacity of a battery bank will not power the A/C unit for any significant amount of time, thus rendering the system practically useless. I worked a little math on this and, assuming my math is correct, a typical 13000 BTU coleman A/C unit will consume about 3800 watts per hour and a set of Trojan T-105 6 volt batteries, fully charged, has about 5400 watt hours available, or less than 2 hours of operation until the batteries are fully discharged. Since we don’t want to discharge our batteries more than about 50%, or about 2700 watt hours, or in terms of a cold RV, about 42 minutes of operation. In other words, not a very practical arrangement.
Enter the Topleader Group Limited our of Dongguan China who were showing their line of DC operated roof top A/C units. The photo below shows their DL-1200 unit.
According to their literature, the AC unit operates on 24 volts DC, at 600 watts, and produces from 6200 BTU cooling. I am going to assume that in the air conditioner has an internal inverter which converts the battery DC voltage to AC in order to run the compressor, either that or it actually operates with a DC motor. Either of these schemes would be different from the typical US made A/C unit which operates from 120 volts AC. In addition, the lower power requirement for this unit brings it closer to being useful for the boondocking RVer.
Consider this, a set of 4 Trojan T-105 batteries connected in series to provide 24 volts DC would provide 5400 watt hours at 100 %, or 2700 at 50% discharge. If the DL-1200 requires 600 watts/hour, this arrangement would provide over 4 hours of operation, or if the A/C is not operated continuously, a fairly good portion of the day.
Unfortunately, the 24 volt series connection for the four batteries is not typical of what we do in the US, and would require a new battery charger, but at least this would be a system that would provide a reasonable solution for boondocking.
Oh, before we all run off and install this system, and hope that we can recharge the batteries with a solar system mounted on the roof of the RV, a rough estimate is that we would need about 500 square feet of solar panels to accomplish this. Maybe just use the old Honda generator?
If you are interested in getting more information on the DC air conditioner, here is there website:
At this time, I don’t know of anyone in the US who is actively importing this product, so maybe this represents a new business opportunity.
P.S. if anyone finds errors in my math, please let me know, or leave comments. It’s been a long time since I did these types of conversions.