12 Volt and Tiny ACs for Nomads

[andi]

Bob recently posted a video about someone with a window air conditioner in the window of their van or RV. I was like, "So 2015."

I saw a van conversion video where a conversion company installs these: KingtecUSA Air Conditioner KTF-1 https://kingtecusa.com/product/ktf-1
Looks like it's typically used for cooling truck cabs.

This appears to be a similar product:  https://www.cruisencomfortusa.com/ 
- HDs/L-12 and HDs/L-24 DC Air Conditioners for your truck or RV (ducting unit optional)

Also this: https://www.amazon.com/dp/B07QSFMQJZ/ - 12V Compact Refrigeration Cooling Systems Air Conditioning Systems with Miniature Rotary Compressor - for Electric Vehicle Chiller Water Dispenser Freezer Electronics Cooling Module DIY (12V,1.9cc)  by CAMPELIFY

Then there are evaporative coolers like https://www.amazon.com/dp/B07CQRPR9Y/

Someone mentioned this in another thread (the portable AC thread) but it's not 12V:  https://www.kickstarter.com/projects/1253665084/zero-breeze-the-worlds-coolest-portable-air-condit - Zero Breeze - The World’s Coolest Portable Air Conditioner - but it's tiny!

I want someone to persuade Bob to do a comparison of AC units that are appropriate to nomad vans and RVs (using only solar, not generators).

 

[abnorm]

""..............This appears to be a similar product: https://www.cruisencomfortusa.com/
- HDs/L-12 and HDs/L-24 DC Air Conditioners for your truck or RV (ducting unit optional)""

WOW !....$4,000 for a small 12 volt electric A/C unit

 

[wayne49]

Buy an RV fridge for $1,200 and leave the door open.

 

[Trebor English]

According to the Kingtec web page the unit uses 47 amps.  By my quick mental math that means 2 hours will require a pair of 100 amp hour AGM batteries (50%) or one 100 amp hour LiFePo4 battery.  By the old rule of thumb, 100 Ah, 100 watt, you will need about 200 watts of solar panel.  

Since 2015 the math hasn't changed.  It still takes a lot of battery and a lot of solar panel and a lot of engineering to put together a mobile off grid air conditioner that works.  It has been and still is possible.  If your climate is such that you only need the cooling while the sun is shining the battery requirement drops substantially.  If you have a large amount of moisture you need to condense out of the air the energy requirement goes up. 

Having a comparison of off grid air conditioning systems is a great idea.  Bob has typically been focused on the low cost end if the spectrum.  I think it might be hard to get him interested in this.  You could get in touch with other people who have air conditioning and come up with a test plan to try one of these truck systems.  By collaborating you could be sure to avoid duplicating what others have already tested.

 

[jacqueg]

Youtuber Hobotech has several videos regarding how he runs an A/C. He spends more money than I would on A/C, btt considerably less than $4K.

 

[jimindenver]

Don't let the fact that something is 12 volt blind you to what you are really getting. Anything that beats the low consumption of the efficient 120 Vac unit I use cost 10 times as much. Specialty 12 volt options like those intended for trucks use more power, produce less BTU's and still cost a lot more.

Yes there are inverter loses to be considered but honestly if you have to worry about inverter loses, you probably should not be trying to run a air conditioner off of solar/batteries. Add to it that all of the people that I have worked with that wanted to be able to run a A/C also wanted to run other things when they were not running it. You will still need a inverter to run things like a microwave, instant pot, cook top, coffee maker, etc. You can do some of those things off of 12 volt but the 120 Vac versions are so much better and less expensive.

Last thing is I recently helped researched the concept of replacing the compressor in inexpensive 5000 BTU window units with a Danfoss compressor. What we found was that a Danfoss compressor was not any more efficient than the high efficiency compressor in the energy star unit that I use. For the time, effort and expense all you would save was inverter losses.

 

[Trebor English]

Air conditioner compressors and refrigerator compressors are sealed units containing the electric motor and the compressor.  A car air conditioner driven by a belt powered by the engine has a shaft seal to keep the refrigerant from leaking out around the rotating shaft.  The sealed unit eliminates the need for the exposed shaft seal.  The sealed unit also makes motor brush maintenance impossible.  That means that all electric, 240, 120, 24 and 12 volt, refrigerators and air conditioners contain a brushless motor.  That means it's an AC induction motor just like Nikola Tesla invented.  An AC induction motor powered by DC means there is an inverter.  It isn't a separate box bought separately but the inverter is embedded in the 12 volt fridge or 12 volt air conditioner.  Unlike the typical inverter used for a Mr Coffee the fridge inverters are 3 phase and variable frequency.  Three phase makes the motor more efficient and easier to start compared to a single phase motor.  The variable frequency makes the gas compression and expansion heat pumping more efficient.  The inverter loss is still in there, not eliminated. 

Bottom line, don't fret over the inverter.

 

[tx2sturgis]

Inverters sometimes get a bad rap here...because of inverter losses....but sometimes the overall solution with an inverter is much more cost-efficient and sometimes it is more energy efficient, and sometimes, it is BOTH. 

Obviously using an inverter is not the best solution in every scenario, but many times it is.

I am often amused when certain devices or appliances are referred to as 'native 12 volt unit'....

Well when it comes to electronics, such as 12v fridges, 12v LED TVs, 12v laptop car chargers, there is no such thing (simple 12 volt heating appliances are NOT electronic, they are electric, and they ARE native 12 volt) 

Sure, 12 volts go in to the 12 volt electronic device,  but internally the voltages are bucked or boosted (lowered or raised) to whatever the internal components need. They do this with some form of internal DC converter/inverter, for lack of a better, longer explanation.

And I have mentioned this a few times, but many times the argument over minute details is irrelevant when trying to answer some basic questions about 12v electronics compared to using inverters with 120v appliances. 

At any rate, using off-the-shelf consumer grade components makes good financial sense most of the time when it comes to cooling and heating a parked vehicle or RV.

 

[Pleasant Travels]

I was gifted one of those portable evap coolers for a car. Perhaps it's because I'm in Arizona, but those things are useless. They simply do not put out enough CFM.

 

[Rabbit]

For me personally, the big problem with a window unit isn't the efficiency, which I find to be excellent, but the fact that it's meant to be mounted in a home-style window. I like to pull over at midnight, be asleep fifteen minutes later, and then hit the road again by 9AM, which doesn't allow for a ton of setup and take-down time of the sort required by a window unit. (Yes. Where I live and most frequently travel, you do in fact need an air-conditioner at midnight much of the year in order to sleep well. It really and truly is that bad. Especially if you have heart trouble like I do.) I've owned two cargo trailers now with no appropriate windows. On the first I cut an appropriately-sized hole and was never entirely pleased with the result, and with the second I'm still making up my mind what to do. My current trailer came with a 13,500 BTU roof air, and I've successfully added a soft-start that allows it to run just fine off a 2200 watt propane "suitcase" generator. If I can find a way to secure the generator adequately to survive night after night in high-crime areas, that's probably what I'll go with for all my usage instead of trying to add a more efficient second unit meant solely for offgridding. It's not an ideal solution (I prefer something I can run overnight off batteries, as my window unit used to in the first trailer) but better than cutting a window-unit hole or paying through the nose for a "boutique" cooling system.

To give an idea of how efficient window units can be, I'm currently using one (plus a dual-hose portable that I bought some time back for another purpose and was just sitting around gathering dust) to replace the perfectly functional (almost brand new when I bought the place) Frigidaire central unit at my home base on all but the hottest days. This (plus the flexibility to only cool one room at a time) has reduced my electric bill notably, which was especially surprising given that the dual-hose portable (often thought to be inefficient but much, much better than a single-hose) is by far the larger of the two. If they made a dual-hose portable small enough, after this very positive experience, it would likely become my converted-trailer solution of choice. But the smallest I've been able to find is 10,000 BTU, and that's just too darned big for what I want to do. Might as well stick with the not-much-larger roof unit and save a lot money, cutting, and aggravation.

 

[Malamute]

I set up my window AC unit in my 4runner in the spring and take it out in the fall when days dont get above the mid 60s. Setup involves removing the large trash bag I put between the door/ac and inside of the vehicle to keep rain intrusion minimal, and removing the small boards I often put on the outside to reduce wind noise. The last part is opening the cargo box, starting the gen, closing the box.

The hard start capacitor reduces the amount of gen power required to start it and allows quieter and longer running by using economy mode on the Honda gen.

So far its been OK over 2 summers I believe. If shopping when sedentary it also allows the dog to go and not worry about her being in the truck when its hot out (to a reasonable degree).

 

[andi]

Thank you for all the great discussion! I'll have an inverter (with 1000 Watt Goal Zero), so I guess my question is which unit uses the lowest amount of energy? I am not a person who needs a lot of cooling. I live in Florida using minimal AC. My issue is keeping my dogs cool when I leave the vehicle.

I don't like window ACs because I believe they are a security risk - someone can quickly push it in and gain entry. Besides, they're not very stealth.

My problem with the roof ACs is that they take up a lot of roof space that I need for solar panels. I'm planning 600 Watts of panels. Also, my van is high roof. Maybe I can get the low profile Coleman and put a rack with panels over the top? Just don't want to build up too high.

I don't think the evaporative coolers are what I want.

So which units use lowest amount of energy? Do all units with the same BTUs use about the same amount of energy?

 

[andi]

Buy an RV fridge for $1,200 and leave the door open.

... or separate the condenser coils and put them under the van. Otherwise you're heating and cooling the van at the same time. Although if it's really hot out there the system won't work very well.

I'll have a freezer (115 Volt 1 amp); I guess I could make ice cubes and leave them in bowls around the van, but I don't think that effect would last long.

 

[tx2sturgis]

I don't like window ACs because I believe they are a security risk... Besides, they're not very stealth.

My problem with the roof ACs is that they take up a lot of roof space that I need for solar panels. 

I don't think the evaporative coolers are what I want.

You dont want roof air, you dont want window air, and you dont want evaporative air....

Pretty much leaves you with a fan hanging from a hook.

 

[Malamute]

I don't like window ACs because I believe they are a security risk - someone can quickly push it in and gain entry. Besides, they're not very stealth.

 Then youre not doing it right. Mine is mounted with aluminum angle metal, screwed to the AC body and 4 pinch bolts to the door/window opening and clamped around the AC body. The bolts are button head allens. If someone happened to have a correct allen wrench, the nuts are nylon lock nuts, they would just spin and not loosen. It would be easier to get in another window. Ive never worried about anyone being able to get in the AC window.

 I painted the AC the same basic color of my 4runner, it blends in to casual observation, but still gets people laughing and taking pics, many asking about it and how it works.

 If youre interested in seeing pics of the mounts I posted them elsewhere and can provide a link. Seriously.

 I use mine regularly even around town so i can take the dog and not worry about her.

 

[andi]

...
Pretty much leaves you with a fan hanging from a hook.

https://i1.wp.com/images.cheaprvliv...p-nlRF00tQ6gKbe2nF0qfZai9ViYsC58bdlcOM7bnWfa4

 

[andi]

 Then youre not doing it right. Mine is mounted with aluminum angle metal, screwed to the AC body and 4 pinch bolts to the door/window opening and clamped around the AC body. The bolts are button head allens. If someone happened to have a correct allen wrench, the nuts are nylon lock nuts, they would just spin and not loosen. It would be easier to get in another window. Ive never worried about anyone being able to get in the AC window.

 I painted the AC the same basic color of my 4runner, it blends in to casual observation, but still gets people laughing and taking pics, many asking about it and how it works.

 If youre interested in seeing pics of the mounts I posted them elsewhere and can provide a link. Seriously.

 I use mine regularly even around town so i can take the dog and not worry about her.

I think I lost the fight to a window AC. I guess a 5000 BTU is the lowest energy I can expend.

 

[Malamute]

I absolutely love mine. I set it on 61 deg and come back and the dog is sleeping, not even panting, everything in the truck feels cold...just about perfect. I also park so the sun intrusion is minimal, and use the reflective window things in the windshield.

Heres some pics and info on what I did, if youd like to see any more detailed pics let me know, Ill see what i have or take some more.

https://bushcraftusa.com/forum/threads/full-hillbilly-window-ac-in-a-vehicle.228995/

With the gen on eco mode it will run 6-7 or so hrs. The hard start capacitor helps this work ($12), otherwise its about 3 or so hrs on normal mode and is noisier and uses much more fuel of course.

 

[Hoot]

Thanks for very helpful text and photos Malamute, and the ".......nobody cares when they are on a mission to save the world and the dog." 
Have unfortunately met them as well, at least I'm more aware of what a fine cover it is for anyone who wants to break and steal your pup.

 

[JohnnyM]

Love your generator setup, Malamute. It has both excellent stealth and security. Well done!

Thanks for sharing this. I've often wondered if the Honda could stand living in an enclosure. Do you feel that it's getting all the air it needs to stay cool inside that enclosure? Looks like you've totally taken care of the engine exhaust and the hot air exhaust. Do you have any other air intake other than that oval cutout on the floor of the box?

Love to see more pics pf the generator if you have them.

Johnny