Smallest, most low profile AC for van to run off solar?

[chris84]

Here is my setup to run a window AC unit.

600 amp hour lithium batteries (7200 watt hours)
400 watts of solar panels
30 amp battery to battery charger
Also my unit is fairly well insulated.

I can easily run the AC for 10 hours or so if I am willing to fully discharge the batteries, but I never really have the need. I am mostly in the northeast and use the AC for 2-3 hours a day or less. In the northeast in the summer the solar panels generate over 200 amp hours a day. The AC draws about 40 per running hour (it usually doesn't run continuously after the first 30-45 minutes). The fridge uses about 40 amp hours a day, everything else uses 20-30 amp hours in the summer, a little more in the winter running the heater (webasto gasoline 2000) than in the summer running the fans. But in the winter I am lucky to get 100 amp hours a day, often less due to the angle and shorter days, and weather.

A system to run a rooftop AC would need to be much larger, I am running an efficient 5000 BTU unit, most roof ACs are 8000+ btu with lower EER. My system (inverter, batteries, solar, charger, charge controller) was over $8000 and I would not be able to support a roof top AC for very long. My van is also fairly large, but insulated to R10 or better in the passenger compartment (the cab is a giant oven if you don't get the windows covered, which I use to my advantage in the winter, but have to be careful of in the summer).

I don't have the AC on the roof, but have it in a partition wall about 14 inches in front of the rear doors that separates the rear storage (and AC venting) from the rest of the vehicle. I have a roof vent (powered) directly over the AC that runs to vent the AC heat, and a window on the rear doors that allows fresh air in. This system allows me to use a small window AC, not cool the areas that don't need to be cooled, and doesn't make the vehicle look too obvious (to some). I didn't want a window AC sticking out my doors in the rear.

 

[1shemp]

$8000? WOW!

 

[tx2sturgis]

On the Air Conditioners that they use on semi trucks, I used to install them. I worked on transport refrigeration units for 30 years. There is a 25 HP Diesel generator hanging off of the side of the truck to power it. They became popular when California restricted the time a truck could idle.

Ours were 120 volt so the driver could use common electrical appliances when they were not running the A/C. The generator had more capacity than the a/c needed, but not enough to run something heavy like the a/c and a microwave or hot plate.

Just FYI, that is one type of APU on CMVs, there are others like the Thermo-King (and others) that use the small putt-putt diesel motor to directly power the automotive style air conditioner compressor with a drive belt off the crankshaft of this little motor, along with an automotive alternator for keeping the truck batteries charged. In fact most of the APU's that you see hanging off the right side frame directly behind the fuel tank, are this type.

They generally have coolant lines that connect the cooling system of the APU motor to the cooling system for the main motor under the hood, with a coolant pump, to keep the big iron block around 50-100 degrees or so even on the coldest winter night. This helps during cranking the next morning since the 10 gallons of oil in the oil sump will be fairly warm. 

Our trucks had large inverters to run the microwave and other 'hotel' loads directly from the starter battery bank, which was being charged by the alternator on the APU.

It all worked very well...until it would quit for some reason at 3 am....I hated when that happened!

 

[chris84]

$8000? WOW!

600 amp hours of lithium batteries were a little over $5000

3000 VA Inverter  $1300
100/50 Charge controller $300
30 amp battery to battery charger $300
Control panel $500
Breakers, 2/0 wiring, 10 gauge wiring, terminals, fuses, etc. $?

But the vehicle is comfortable and saves me from spending 3 or more nights a week in a hotel (or paying at least $700 a month in rent)
and serves as my only vehicle when I am on location working. I figure it saves me much more than it cost me.

 

[DannyB1954]

Just FYI, that is one type of APU on CMVs, there are others like the Thermo-King (and others)

I worked at a Thermo-King dealership for over three years, then on sea going shipping containers for 20+ years and then at the end a Carrier Transicold dealership for another three years.
For small delivery vans they do have a compressor that is driven off of the vehicle engine. This is the only time refrigeration lines will come out of the reefer itself. The vehicle engine needs to be running. Sometimes these will also have a electric compressor up top so that the refrigeration can be used plugged in over night. With the larger units for box trucks, the engine and compressor are up in the reefer unit, not down below. The engine is only separate of the reefer if it is an electrical generator and it is powering a motor up top that drives the compressor. The Auxiliary Power Units are generators. Their engine cooling lines are plumbed into the truck engine not only to cool the APU but also to keep the truck engine warm for easy cold weather starts. There are no refrigeration lines attached to the APU. It is strictly an electrical generator, (Just FYI).

 

[tx2sturgis]

Yes, on how the sleeper cab climate control APUs are configured and how they work....I was adding to your information, not challenging it. 

I was not referring to refer units for perishable products in the cargo compartment or trailer, nor was I referring to refrigeration lines exiting the unit.

They do have short refrigeration lines that run to the under-bunk evaporator unit, obviously. 

When I said the coolant lines are plumbed into the main engine coolant lines, that is correct because I am referring to the engine coolant, in other words, antifreeze and water, not freon style liquid/gas refrigerant of any R-number.

Our Thermoking Tri-Pac APU units (not cargo temperature control units) did have an integrated radiator (for coolant) within the APU cabinet, with a fan, so the main propulsion engine coolant or cooling system was not used for cooling the small APU motor. There is a refrigerant condensor with an electric fan mounted on the back (or sometimes the side) of the cab, for extracting heat from the refrigeration system.

The reason I even brought up the subject of commercial APUs is that I can see a need for compact, light duty units that could be built by a company like Honda or Generac or similar, they have the know-how to build one of these in a small, compact, lightweight size for RVs and vans....if only they would make them, I'm sure they would sell, as long as the price was reasonable.

 

[DannyB1954]

Mounting on vehicles is a problem. All Semi trucks have a frame that is easy to get to. All frames are very similar. Those APU's were not light in weight. You can buy diesel generators but would have to figure out where to put it. Trailer hitch mount would be the most universal, but then why not put on a cargo basket and bolt it to that?

 

[tx2sturgis]

It's OK, we'll get thru this. Yes, the typical commercial APU is about 400 pounds, more or less, and we had a federal weight exemption for it. 

But my idea for small consumer-level APU is that they (the manufacturer) might design and build a small, lightweight, quiet, APU in about the same form factor as, let's say, a 2500 watt Honda inverter generator.

Easy to carry, store, and transport. 

The primary difference is that like an APU, the small air conditioner compressor is driven directly off the crankshaft of the diesel (or gas) engine. There is no conversion to electricity, then back to mechanical motion, as with a genset running an electrically powered A/C unit.

There could also be a shaft driven 12v generator, to keep the house batteries charged.

Think of the weight and size of the typical Onan genset in the typical motorhome. My idea for a small compact RV APU would easily fit in that same space.

Efficiencies would be higher, complexity and reliability should be improved, and cost, well....who knows. 

But if I build one in my spare time, you will be the first to know!

 

[highdesertranger]

thanks guys this is like a lesson on APU's. I assume APU stands for "Auxiliary Power Unit" or something to that effect. highdesertranger

 

[tx2sturgis]

Yes, most states and/or populated counties and/or major cities in the USA have enacted anti-idling laws over the last 20-30 years that apply to commercial trucks primarily, so the APU (auxiliary power unit) has been the answer to those laws, since they can provide cooling, heating, and/or electrical power for 'hotel' loads as they are called in trucking lingo, and might be called 'coach' or 'house' loads in RV language.  

Typical hotel loads in a commercial sleeper cab are 12v AND 120v loads, things like a microwave, small frying pan or maybe a toaster or induction cooktop, refrigerator, charging a laptop, powering a TV, maybe a C-PAP...(night time breathing assistance machine) interior lighting, maybe even a gaming computer... or in my case, powering ham radios and charging my drones!

A truck driver really needs to get his or her sleep in a climate controlled environment, no matter how extreme the outdoor temperatures are.

So all I'm saying is, that the technology, if downsized and cost effective, could be used to provide those same benefits to the typical RVer, if it was available.

 

[DannyB1954]

So what you are looking for is a gas/diesel/propane powered air conditioner for rv's? No electricity involved for the compressor.
They would need to make it like a window air conditioner. Otherwise with the engine being on the outside, and the evaporator on the inside, refrigeration lines would need to be run inside of the vehicle. This would not be very portable. The engine would also need to be self starting so that when the inside temp came down, it could shut off.
You could fabricate something like this with a lawn mower type engine and a Compressor off of a car, but it would be a lot of work to solve a small problem. Every external driven compressor has a leak, maybe very small, but they all eventually need service.
Money is the reason for most things. That type of system to make and install, (if you are paying for labor), would greatly exceed the cost of an inverter generator and a sealed A/C unit.

 

[tatajer]

not sure how well these are, one youtuber said he shook it apart off roading.
24v 2k BTU https://www.rigidhvac.com/store/products/151800
12v 1.5k BTU https://www.rigidhvac.com/store/products/393758-rigidhvac-micro-air-conditioner-dv1910e-ac-12v-pro

based on ~20BTU/sq ft. these should be adequate for a VAN

 

[Dakotalee]

I forget exactly what they are called but I'm going to say splitter units. They are popular in other countries because they don't use AS MUCH electricity. They are heater|ACs in one unit. If I was going to do AC thats where I would start.

 

[LoveCareThinkDo]

I have seen air conditioners made for dog houses for as little as $200. They are very low BTU units, but also don't use as much electricity. Instead of being a single box that you stuck through a hole in a wall. They are an external unit with vents leading to and from the cooled area.

I have never tried one. But they might be worth a look.

 

[chris84]

not sure how well these are, one youtuber said he shook it apart off roading.
24v 2k BTU https://www.rigidhvac.com/store/products/151800
12v 1.5k BTU https://www.rigidhvac.com/store/products/393758-rigidhvac-micro-air-conditioner-dv1910e-ac-12v-pro

based on ~20BTU/sq ft. these should be adequate for a VAN

Expensive and not much more efficient than a window unit.

1500 BTU and draws up to 8 amps according to the specs.

 

[debit.servus]

TX2sturgis, I want to see this made too. A Minimum Viable Product would be a 1 / 2KW inverter generator with a self-contained mechanically driven A/C system (attach your flexible ducts and done), AC output with full-amperage 12v output(s). With the additive manufacturing revolution establishing itself here in the USA, you can very likely avoid working with the chinese directly.

If anybody wants to execute on a market-disrupter in this space, develop a standardized module system with each module no more than 2x2x2' in size. Each module should be mechanically driven, in a standardized way so any to-spec module can be driven. Each module would do a unique function, and all fluid & electrical lines should be fail-safe quick connects. You could use 1 inch impact drive socket for the mechanical connection to each module, driving home the simplistic standardization in the subcounscious mind.

A great prosumer-grade modular system would capture the attention (and sales) of many different niches, including the general camping, tailgating, jobsite, boating, sailing, overlanding, basecamp, off-grid and RVer markets.

The heat of the system is a 4-stroke engine module (with fully automated remote start).
The first 3 modules you should have on day 1 are:
1: A self-contained water-loop chiller module using a standard size hose fitting.
2: An inverter AC power module (2KW) with a faceplate like the portable Honda / Generac (no need to reinvent the wheel here).
3: An air compressor module, that entices the trades (Business to Business).

Later on, come out with more niche modules like:
4: a DC power module (generate 12-48v upto 1000 watt output)
5: a Fuel tank module, to extend the runtime of the engine module.
6: a water pump module.
7: an electric drive motor module, if you don't want to drive the system with a gas engine.

If you're want to know how to sucessfully bring this to market; you need to read The Millionaire Fastlane, by MJ Demarco.

 

[debit.servus]

This is the smallest window A/C unit I've found.
https://www.homedepot.com/p/LG-Elec...dow-Air-Conditioner-in-White-LW5016/206520593

For non-electronic A/C unit like this, you don't have to settle for a conventional installation. You could mount the whole unit outside, and duct the cold and return air through insulated ductwork. If I wanted a stealth installation, this is what I would do.

Take 1/2" & 1" rigid foam board, 3 or 4" semi-rigid ducts, construction adhesive, foam insulation tape, and duct the air conditoning inside. No needing to mount an A/C through your rigs walls or take out a window, when you can duct the cold side of a window unit.

 

[andi]

I'm so sorry I didn't find this thread before I just posted a new one! I think it's what you're looking for: "Tiny & 12 volt ACs" - asking for someone [Bob] to do product reviews in vans.

 

[VanFan]

You could get a Dometic under bench AC unit. They use them in the truckers bed cab area. That way you have the roof for solar

Maki,
I am interested in learning more about this.  Unfortunately, the installation manual at their website will not open in Adobe.  (The User's Manual does.)  I am assuming an opening to the outside of the van is required.  Are you familiar with how these are installed?  Thanks!

 

[Pusher]

This company did a kickstart a few years back for this purpose. To make a smaller unit. I think the rooftop unit became a no go for you if I read between the lines.

I've kept my eye on this startup company for a few years now. They got the crowd funding then couldn't meet the dimensional criteria they originally set. I think their prototype kept overheating with the small size they were originally trying to exchange with. They added an inch here and there, and finally just started shipping.... a little over a year after their projected completion date.

All that to say, their warranty might last longer than the product and company. It's a new shape to an existing design though and at 40 pounds is manageable. Maybe it'll tickle your fancy
https://www.kapsulair.com/