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Old 04-12-2016, 03:35 PM   #1
Mini-Skoolie
 
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Aircon from an inverter?

HI there,

I have had a quick look through the threads and haven't found anyone discussing this idea in detail. I hope i haven't missed it.

I have just bought a Ford e350 7.3 diesel based school bus Iím turning into an rv. There was no aircon installed in the bus and the wife says I have to get that resolved. So, I am thinking this:

Install a high output alternator (150-200A) feeding a 250Ah deep cycle battery bank, feeding a 3kW inverter and then a domestic aircon (maybe like this one - Haier 8,000 BTU 250 sq. ft. Cool Only Portable Air Conditioner with 70 Pint/Day Dehumidification Mode and LCD Remote Control-HPRB08XCM - The Home Depot).

Iím no electrician, but here are my sums. The aircon claims 6.3A required, but I am told that a domestic aircon could draw up to 5 x on start up, so I need to prepare for 31.5AC amps although this seems ridiculously high and well past the normal fuse range. Nevertheless, 31.5A x 110V = 3465W. 3465W/12V = 289DC amps on startup. Nominal running should be 6.3A x 110v = 693W / 12V = 57.75DC amps which is easily in the range of these alternators claimed output even at idle (600rpm).

I know there will be loss in the system, and the output/demand of these items will be overestimated/underestimated respectively, and i need to keep the DC wires short, and the alternator wont last more than a few years, but I have also heard people running 15,000 btu aircons on 2,000W inverters, so my solution seems reasonable for good aircon compared to other solutions.

Does this all make basic sense or am I missing something?

Thanks,

Gyronaut
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Old 04-12-2016, 05:25 PM   #2
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Howdy. Just to throw a wrench into your thinking, check out the mini split systems. It's a small household type heat pump.
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Old 04-12-2016, 05:38 PM   #3
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look into this if you are looking at a portable floor standair-conditioner.. I talked to the gentleman through email and he states it maxxes out at about 1000watts.. however since it is variable Inverter driven the compressor speeds up and slows down as needed and since it doesnt cycle much you wont constantly surge your batteries..

Climax Air | DC Inverter Portable Air Conditioner w/ Dual Hose | Worlds Most Efficient Portable AC

these are $899 plus shipping... lead time about 3 days....



it is an Inverter style SOFT-START unit and will not have a huge startup draw like a standard unit.. its 110 volt so you can run it on a 12 volt to 110 volt inverter or on shore-power if your bus is parked at a campground.. one unit wont cool a whole large bus but it will help...

minisplits as mentioned above are great except they have a Large outdoor condenser that needs to be Located somewhere.. you wont find a mini split that can fit under the skirt on a bus..

-Christopher
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Old 04-12-2016, 07:31 PM   #4
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I have inverter mini splits that can run off my inverter. I can run both on one 15 A circuit on cool. On start up one draws about 2A very slowly increasing to about 7A.
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Old 04-12-2016, 07:35 PM   #5
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Thanks. I don't mind a split unit and could probably mount it on the back wall above the door. I had one on my boat years ago and it worked very well. However, in this installation, power consumption is the key. Im hoping there are some DC guys here who might endorse or poo poo my math.
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Old 04-12-2016, 07:38 PM   #6
Mini-Skoolie
 
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Quote:
Originally Posted by cadillackid View Post
look into this if you are looking at a portable floor standair-conditioner.. I talked to the gentleman through email and he states it maxxes out at about 1000watts.. however since it is variable Inverter driven the compressor speeds up and slows down as needed and since it doesnt cycle much you wont constantly surge your batteries..

Climax Air | DC Inverter Portable Air Conditioner w/ Dual Hose | Worlds Most Efficient Portable AC

these are $899 plus shipping... lead time about 3 days....



it is an Inverter style SOFT-START unit and will not have a huge startup draw like a standard unit.. its 110 volt so you can run it on a 12 volt to 110 volt inverter or on shore-power if your bus is parked at a campground.. one unit wont cool a whole large bus but it will help...

minisplits as mentioned above are great except they have a Large outdoor condenser that needs to be Located somewhere.. you wont find a mini split that can fit under the skirt on a bus..

-Christopher
Thanks Christopher. I had not seen these before and will contact them for their thoughts on my plan.
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Old 04-12-2016, 08:44 PM   #7
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Quote:
Originally Posted by gyronaut View Post
Thanks. I don't mind a split unit and could probably mount it on the back wall above the door. I had one on my boat years ago and it worked very well. However, in this installation, power consumption is the key. Im hoping there are some DC guys here who might endorse or poo poo my math.
where would you mount the outdoor unit? the inside unit is easy.
-Christopher
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Old 04-12-2016, 09:04 PM   #8
Mini-Skoolie
 
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where would you mount the outdoor unit? the inside unit is easy.
-Christopher
Probably outside above the rear door, with the internal unit above the door inside. It'd be a little bulky for my small bus, but if it proved to be the best option, I'd make it work. That said, this one looks like a good option if it performs as promised - Climax Air | DC Inverter Portable Air Conditioner w/ Dual Hose | Worlds Most Efficient Portable AC
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Old 04-12-2016, 09:17 PM   #9
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I've seen people mount them as you described. Apparently that configuration works quite well and obviously would be relatively easy to hook up because of the proximity of the two units.

This is a rookie question about these mini split systems. They are actually heat pumps, and heat pumps not only make AC but also make heat in the winter?
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Old 04-12-2016, 09:18 PM   #10
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depending on your timeline for A/C I plan on ordering one of these for use while im working inside my bus on hot summer days.. I'll be able to measure its performance and power usage.. I wont be ready for a couple weeks though..
-Christopher
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