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Old 08-26-2016, 06:38 PM   #1
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12 Volt Air Conditioning?

So, in my search for air conditioning options I've come across a couple sites selling battery-powered units for trucks: Arctic Breeze and Cruise N Comfort. They are marketed as a solution for idle-free zones to keep things cool without running an engine. They run on 12 or 24 volt DC power. They are smaller units, running 7,000-12,000 BTUs depending on what you get, but I imagine with proper insulation one or two of these would do the trick, and that being DC they would be much more efficient.

The other thing that I like is they function like the mini split systems that have been discussed here but they are specifically designed for vehicular applications, so I imagine they may be a bit more robust.

Just yesterday I noticed a Semi truck with one of these condensers mounted on the back of the cab, so I know they're out there, but I can't seem to find a lot of reviews or opinions on them. Anybody here have any knowledge, experience or opinions in this area?
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Old 08-26-2016, 07:57 PM   #2
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DC Air Conditioners 12 24 48 volt

Don and Mary
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Old 08-26-2016, 08:20 PM   #3
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I checked it out. Arctic Breeze makes a 12 volt model with the following specs:

Technical Specifications
Our 12V system draws 45 amps and provides 8000 BTU/hr of cooling and heating. Based on a duty cycle rate of 50-60%, this unit consumes only 350 watts/hr on average. (cooling)

The condenser/compressor box is made out of 1/8 aluminum and can be mounted directly behind the cab or hung off the frame rails with the brackets. It features a removable lid for easy access to all the components.

The evaporator can be mounted on a shelf, directly on the back wall of the cab, or in a storage compartment (for sleeper applications)





Power usage (max)

600 watts/hr

Power usage (avg.)

350 watts/hr

Minimum Alternator

180 amp

Dimensions Cond

25W x 14.5H x 13D

Dimensions Evap

9.5H x 9.5W x 11D

Air Flow

230 CFM

Cooling output

8000 BTU/hr


194 lbs (88 kg)

Sure starts! Each system comes complete with an integrated low voltage cut out switch to prevent draining the starting batteries.

That would require quite a battery array to sustain its electrical needs. Other brands may be more efficient--I don't know.

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Old 08-27-2016, 01:11 AM   #4
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4k for one 8000BTU unit ?

What is a lot of money, hence the lack of review.

I did a lot of research on this and I bought a Coleman Match 3 P.S

Coleman Mach - Mach 3 P.S. Power Saving RV AC | Airxcel

1300W max(desert) 10A AC, I can run it with my solar power ( 5 panels at 1300W) and it cost me $1200 with all attachment and control unit included New.

I look at the 12/24v system but the prices are way to high and because of that impossible to find in wrecking yards.
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Old 08-27-2016, 07:35 AM   #5
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if ytou are inclined to build your own you can buy a DC 9,000 BTU compressor from jegs (they make their own)
and then source the rest of your pieces elsewhere.. junkyard automotive parts... new parts, whatever you choose,,.

the reason for the high cost of these DC systems is in many cases DC compressors require a controller to always provide constant voltage or to vary the speed of the compressor based on load.. these systems are marketed to professional trucks where they want to conserve battery and have long run-times for their A/C units..

these same type units are used with tri-pak;s and other APU's..

regular 120 Volt minisplits will run from inverters and batteries.. since they are soft-start they dont surge the 1230 volt line when the comopressors start..

HOWEVER a minisplit running at its Peak outpiut is inefficient.. a mini split running at 80% or less of its capacity is VERY efficient.. Ive done a lot of studies on power usage vs BTU output on the 3 splits i have running in my house... Oversized evaporators got me up to about 90% compressor run and srtill be efficient..

a 12,000 BTU minisplit (120 volt) running at full power will use 1100-1300 watts if the heat-load outside is High (requiring the outdoor fan to run at max speed and also higher head-pressures to over-come..

at 1200 watts your batteries dont last real long! depending ion the type of pack you have. theres some Loss in the inverter as well..

so its basically a toss up... spend the big money for true 12 volt stuff or buy more batteries and insulate real good...then use 120 volt A/C.. to me i'd opt for good insulation and more batteries...

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Old 08-27-2016, 08:05 AM   #6
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Coleman Airxcel 13500 BTU 1320 watt desert mode

Arctic Breeze 8000 BTU 600 watt continues

It seems that the arctic breeze is a lot more efficient.

My solectria electric car ( geo metro) uses a 500 watt DC motor with a tooth belt to drive I assume the original airco compressor .

I see not reason why you could not do that with any other vehicle. Especially with the big buses that have plenty of space under the hood.

It sure would be a great experiment to see how efficient or not the design of the automotive airco components are.

later J
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Old 08-27-2016, 09:39 AM   #7
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the older and cheaper electric cars used a belt and motor with a regular automotive compressor... it turned out to be inefficient and somewehat unreliable as finding a constant-duty motor sized big enough to spin an A/C (and keep the motor cool) was tough..

so the later electrics and the hybrids went to variable speed DC motor compressors.. all hybrids built in the last 10-12 years (more for prius) have DC variable speed compressors.. some like the Nissan LEAF even have a heatpump option.

you dont have to locate all of it under the hood if running a DC motor.. it can be anywhere...

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Old 08-27-2016, 12:17 PM   #8
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I might be inclined to consider one of these 12V A/C systems ... if I consider 800W of solar, and ~600 of A/C that would, in theory, still keep charging the batteries. Would that be enough to keep 30' of bus cool(er)?
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Old 08-27-2016, 12:50 PM   #9
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I do not know about the pumping efficiency of the automotive compressor?
The Dc motor and tooth belt should be pretty efficient. I would think a least better then the normal AC motors in compressors in normal airco and heat pumps. I am sure that Nissan Leaf and so have a very high efficiency but they also run on higher battery voltages. So ultimately there might be not any gain if you first have to convert 12 VDC to 300 VDC.

Yes I agree it does not have to be under the hood but if you use the belt driven compressor then that would be the easiest and cheapest solution. With attaching an extra pulley to the compressor you can keep the airco running of the engine when you are on the road and of a 12 volt motor when you are boon docking.

I will attempt that with my E350. Probably have to relocate some stuff to make space for the DC motor.

Even if I have to make an adapter so that I can hang a DC motor in there and have to take it out while I am driving then that would be still beneficial from a simplicity standpoint.

I doubt that I could find an AC shop wanting to work on a system that has a Nissan Leaf compressor in a bus. or may be I should say that I would not trust them

Later J
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Old 08-27-2016, 05:05 PM   #10
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im not one to ring stuff up, though I am one to definitely build stuff... double pulleys and hanging motors sound like stuff to break and fall apart..

an electric motor that is run by a bus that has a big enough alternator to power it sounds like the way to go if you are going to run DC for the air conditioner...

Bosch 200 amp low RPM alrternators (SB-200) are easy to come by and will run a lot of stuff..

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