A lot of the calculations here are probably a bit pessimistic on the real-world energy consumption of an AC unit. Our Coleman Mach 10 (13.5k btu) draws 1200-1300 watts with the compressor and blower running, and around 200 watts with just the blower. In my experience, the compressor doesn't run anywhere near 100% of the time, so I've been able to get 18-24 hours of runtime on a charge without much difficulty.
It's certainly true that AC does use a lot of energy, but that doesn't mean it's not possible (or practical) to build a battery system to run it. Personally, I find the ability to run the AC on batteries very useful.
I ditto that, it’s even better than I thought it would be.
A helpful hint from Bob was to run it on low auto cool.
I am wondering if anyone here has a propane air conditioner. I didn’t know they made them until this post and looked them up. Don’t know the anything about them other than a quick search. Thanks
I am wondering if anyone here has a propane air conditioner. I didn’t know they made them until this post and looked them up. Don’t know the anything about them other than a quick search. Thanks
OK, curiosity piqued, but my search does not reveal any that are designed for or seem suitable for an RV installation?
Please post a link if you find any that would be candidates for a trailer installation, rooftop or otherwise.
I have the Escape 21NE with the Coleman 13,5k Mach 10 without easy start, a 2400W inverter, 2x lithium batteries wired in series for 170Ah at 24 volts. I do have more than typical solar but one panel or another is shaded by the A/C depending on location of the sun. There are 4x 160 watt 12 volt panels in series and 2x 210W 24v panels in series. I wired them in series so when one panel is shaded the others keep working.
I am in Tacoma, WA. Yesterday I decided to run the A/C and document the power usage and report it here. When I started, the outside temperature was 81°, the roof was 104°f, the trailer side in the sun was 90° - 98°f depending on its angle to the sun, the trailer side in the shade was 86°. The inside temperature of the trailer when I started was about 90°. I set the A/C to 72° and selected Cool-Low-Auto. This selection reduces the fan speed and turns the fan off when the compressor turns off. The fan uses a lot of watts. I have never used the high setting except to see what happens. I have run the the A/C all night when in the high 90°s. The batteries were down to 7% SOC in the morning. They recovered 100% the next day. That was somewhere in Arizona in April or May so the solar was good.
Yesterday I ran the A/C from 1:40pm to 3:25pm. I ran the 700 or 750watt microwave twice, once while the A/C was on and once when it was off. I did this to show that the microwave uses as many watts as the A/C. Initially the A/C ran about 18 minutes to lower the temperature to 72°. Once the temperature was stabilized the A/C ran 4 to 6 minutes and was off longer than 20 minutes before it cycled on. I was going in and out of the trailer throughout the run and had the max fan open for the first part of the run. The sky was clear.
I include a few pictures the energy situation. One at the beginning when I first started the A/C, one with the A/C and microwave on, one later with microwave on and A/C off, and then at the end. You will note from the pdf file that the solar had pretty much recovered the batteries after the A/C had stabilized the temperature inside the trailer at 72°. Remember, I was running the microwave too.
The first picture is when I first started the A/C, the second picture is when I turned the microwave on while the A/C was on, The 3rd picture is when the battery was lowest SOC, the 4th picture is when the battery recovered to 99% and the microwave is on. I did not change the picture file names. The file name is the date and time of the picture. I used regular time in the pdf.
Conclusion: I can not run the A/C all day and night when it is hot but I can easily run it to take the edge off and at bed time. Maybe the attached pdf can help people decide whether they want to run A/C from the battery or not.
As you can calculate from the information, the A/C is drawing 9 amps at 120 volts (it is running on LOW setting). The high setting would be higher.
I just measured the sound level with a phone sitting on the dinette table. A/C off 30dB. With A/C on 55dB. That isn't loud. I know it doesn't bother me and I wear hearing aids which makes it difficult to understand conversation when there is background noise. The other day I was in a van with Dometic A/C and when it was on I couldn't participate in conversations. I know I don't have any trouble sleeping with it on but that is without my hearing aids so others might find it annoying.
Here's some more information on 12v AC units. The Marbu 12v DC air conditioner draws about 55 amps on high (about 660watts), and provides 11,000 btu. The coleman mach 13500btu draws 1500 watts, over twice what the Marbu draws. In addition eliminates the "hard start" issue and the noisy clunking off and on of a traditional AC unit because it has a variable speed compressor.
Once you have changed out the old AC for this more efficient DC-powered unit, you would no longer need to upgrade your inverter, and you could just run the air conditioner like any other DC load in the trailer. With say, 400 amp hours of lithium batteries, you could easily run your air conditioner for 6-8 hours. You would also need a lot less solar because you wouldn't be wasting so much on an inefficient air conditioner.
I fail to see the Mabru marine AC as a viable option for our small trailers. First, where to mount it? Second, it's about 5 grand.
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I fail to see the Mabru marine AC as a viable option for our small trailers ....
Look to the RV model intended for rooftop installation, not marine models. Still not inexpensive at $2600, but a far cry from $5k in a common RV configuration.
Look to the RV model intended for rooftop installation, not marine models. Still not inexpensive at $2600, but a far cry from $5k in a common RV configuration.
I'm not suggesting it, just pointing out the likely most applicable model for our small trailers.
The specs on that Marbu unit are fiction. Read some of the reviews on the van life forums. There's not really any magic that can somehow half the amount of energy needed to compress refrigerant. Physics is physics...
The specs on that Marbu unit are fiction. Read some of the reviews on the van life forums. There's not really any magic that can somehow half the amount of energy needed to compress refrigerant. Physics is physics...
Good warning and info for some I'm sure; myself, I've no interest in the unit at all.
Look to the RV model intended for rooftop installation, not marine models. Still not inexpensive at $2600, but a far cry from $5k in a common RV configuration.
I can see how the DC unit will be more efficient, it's just a question of how much more efficient it will be. AC systems in general operate most efficiently when they run all the time and cycle as little as possible. Not only does this improve efficiency of the refrigerant cycle, it allows the whole unit to run more smoothly and quieter, without the periodic clunking of the compressor going on and off. DC units use a variable frequency inverter to vary the speed of the compressor to achieve this, whereas AC units cycle on and off.
As to cost, consider that many people already have a small inverter that runs everything except the AC, and you can avoid the cost of having to upgrade that to a large 3,000 Watt+ unit, which offsets some of the cost of the more expensive DC air conditioner unit. If it is more efficient, you might also be able to get away with less batteries and less solar as well, so in the end the total cost might not be that different.
One never knows how it will perform in real life, as most manufactures exaggerate their performance numbers to some extent. Someone will have to try it and do some testing to know for sure. Right now I just use a pair of generators running on propane and no solar at all, but I keep an eye on the technology.
To run it any length of time you'll need 4-6K amp hours of (preferably) lithium battery's.
At least a 3K watt inverter.
Ideally, 8-10K watts of solar (and nice sunny days) to recharge those battery's in a timely enough manner to make all this worthwhile.
The heavy duty wiring that will replace most of your existing 120V system.
I don't think you can get out for under $2K but possibly under $20K.
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Not exactly the same as the OP but maybe a useful data point. I have E19 with 11K BTU Domestic AC and if I switch off the battery disconnect switch (so battery will not charge) and plug the shore power cable into 30 amp port on Bluetti AC200MAX (2400w) It will run the AC. It won't run it forever but I think the use case is to stop at a rest area and cool the trailer down for a few minutes on a hot day. My main use case for the Bluetti is camping in the shade and parking my pickup with 400w solar in the sun to charge the Bluetti, which I then use to charge the trailer battery next morning.
I've posted this photo before, although I'm not sure it was here on the Escape forum. Anyhow, a couple of years ago I ran into a retired diesel generator (large 100K units) company owner that decided to run his Class A via solar. 4000 watts of panels (3 are missing waiting for mounting hardware) and 2K amp hours (20 batteries) of Battleborn batteries inside the trailer. He runs his AC, even charges his electric car.
On edit - I checked my notes - 20 Battleborn 100 amp hour batteries or 2K, not 10K...
We have a large system that can run 1 or both 13.5K roof top AC units at about 100Ah of batteries per hour per unit.
With our 3000W or solar panels we can run one with no drain on the batteries during full sun, if you do the math our 1000Ah battery bank can run for about 6-7 hours overnight with the rest of our devices and leave about 25-30% capacity remaining when the sun comes up.
When it's really hot the answer is you gotta find a plug...... if it's only hot for a few hours in the afternoon AC on solar can be a reality.
I have about $15K in equipment (Victron and Lion Energy + panels and a rack system) and I did all the installation myself....... you have to ask yourself how important it is to be able to run AC off-grid vs finding a plug when it gets real hot
Curious as to why you don’t use the solar to charge the trailer batteries and skip the blurting battery.
I have solar on the trailer, 190w on the roof and a 200w portable panel. If the trailer gets good sun, like at Quartzite, that's all that's needed. But if I'm camping in Yosemite valley in the shade then I can park the 400w on the pickup someplace else in the sun.
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