Teardrops n Tiny Travel Trailers

The Air conditioning problem is one that has really been nagging me. I want my cake and to eat it too, and after some research I think I (we) can have it all for a reasonable price.

I was planning on a standard 5000 BTU AC, but these things take too much power to be supplied by any reasonable number of solar (PV) panels that can be carried on a small trailer (not to mention the cost), and I'm a big supporter of using PV.

My next option was using a swamp cooler. OK, but I want to be independent of 30 days at a time. That would take a lot of water to feed the cooler, then I would have to add my own needs to that demand. Just too impractical to have to haul around 150-200 gallons of water. And, when it's 120 degrees out, even with only 10% humidity, you are going to be hot even with a swamp cooler.

The key to economical (in money and energy) cooling is having very good insulation in the trailer. I'm planning in the area of R-25 in the walls, and 50% more in the roof. Most wont need that much, but I like to be different.

Assuming you have good insulation, a tiny AC will do the job I think. The only problem, is finding small air conditioning units that are cheap enough to afford, and DC powered would be nice (avoiding the need and cost of a big inverter.) Well, I think I have found exactly what we have been after, along with some other alternative units that almost fit the bill .

Check out http://www.alibaba.com/catalog/121296/12V_DC_Air_Conditioner.html
It's a 12 or 24V DC-powered air conditioner, that I am sure i using efficient heat pump technology. What's really cool about the unit, is it's split. Meaing you get to mount all the noisy stuff (condenser unit) outside the trailer, and only have the quite (cooler) part inside with you.

It's cooling capacity is rated at 300 Watt/1020 BTU and it only uses 100 watts while running! This thing will run off of a couple of solar panels! It's almost too good to be true. Only problem is finding a supplier. You may have to order a "sample" directly from the manufacture for the listed sample price of $750, but I think we can get them at the price of $474, as this is also listed as the price on another page.

Assuming there is a flaw with the above unit that I failed to see, or you need more cooling capacity, there is also small wine cellar coolers that will probably work, but use much more power! Instead, buy two of the 1020 BTU units above.

Here are a couple of picture of the unit:

Wine cellar coolers:
http://www.wineenthusiast.com/Shopping/ ... &subcat=CU (several brands)
http://www.wines.buy-and-get.com/detail/Odyssey-3100-BTU-Cooling-System--Max-Room-Size---900-cu-ft.html
http://www.wines.buy-and-get.com/detail/Odyssey-2300-BTU-Cooling-System--Max-Room-Size---600-cu-ft.html
http://www.wines.buy-and-get.com/detail/Odyssey-2000-Slim-Cooling-System--2000-BTU-.html
http://www.wines.buy-and-get.com/detail/Odyssey-1500-BTU-Cooling-System--Max-Room-Size---300-cu-ft.html
http://www.wines.buy-and-get.com/detail/2200-BTU-Grand-Cru-Cooling-System.html
http://www.edifyingspectacle.org/thanks/type_browse/mode_3741581/ (search through the list for many models)

So, what do you guys think?[/img]

Two or three at $750 plus shipping from Malaysia? Plus the extra weight at 40lbs a piece, the 5,000 BTU window unit is still the most economical option for now.

There are other alternatives, but they are not easy to implement for a DIY'er and most involve ammonia which is considered a hazardous material.

Doing some more searching on the small 12VDC air conditioner and the company the builds them, reveals some more info.

Some highlights:
They are using high quality Danfross compressors, and German control electronics.

I found two different prices listed-- $750 and $474! $474 is a great deal for one of these! Maybe a group buy of these things can get it down even more, or at least save shipping costs?

Warranty is 1 year, and they have a 30 day money-back. The company seems to be a small cottage-industry type business.


---------------------------
Product Description:
Model: DC1
Compressor: 12V or 24V compressor
Cooling capacity: 300 watts (1020 Btu)
Cooling space: 6 ft x 4 ft x 6 ft (144 ft3)
Electricity: DC 12V @ 8.0A & DC 24V @ 4.0A
Refrigerant: HFC-134a
Ambient air temperature: 24 deg C to 33 deg C
Off-coil (breeze) temperature: 18 deg C to 21 deg C
Wireless Remote Control: Microprocessor (temperature, thermostat)
Temperature control: IC thermostat
Dimensions:: (L x B x H)
Cooling unit (7.5 kg): 31.75inx5.75inx10.5in (805mmx145mx265mm)
Condenser unit (11kg): 14.5inx10.0inx9.0in (368mmx254mmx229mm)
Casing: Plastic and painted steel
Weight (approximately): 18.5kg
Unit Price: USD$750
Origin: Malaysia
Supply Ability: 4 weeks for delivery


12/24V AIR CONDITIONER
PRODUCT FEATURES:
~ Very quiet in operation
~ The compressor is used together with an electronic unit which provides overload protection and destructive battery discharge
SPECIFICATIONS:
~ Operates on 12 OR 24 volts direct current system from battery or DC generator
~ Uses R134a refrigerant which is CFC free
~ Current consumption for 12V system is 7.5 amperes and for 24V system is 3.75 amperes at evaporating temperature of +10 degrees Celcius.
~ Cooling capacity is about 300 watts
~ A typical operating conditions in a room of 6ft by 4ft by 6ft (144 cubic feet) is shown below:
The whole system's current consumption: 6.5 to 8 amperes
Ambient temperature: 25 to 33 degrees Celsius
Condensing temperature: 40 to 45 degrees Celsius (135 to 152 psig )
Evaporating temperature: 8 to 12 degrees Celsius (42 to 53 psig)
Room temperature: 23 to 25 deg C
Off-coil (breeze blowing from the evaporator): 18 to 21 deg C
~Weighs about 15 kg
~Color bond and fibre glass panels
NOTE: The cooling capacity of the air conditioner is about 300 watts, so temperature drop inside the room is limited. But due to lower humidity and between 5 to 10 degrees Celsius lower than outside air ambient temperature, it will provide a reasonable comfort zone.
USES
~ small room, approximately 6ft by 4ft by 6ft or approximately 140 cubic feet
MODELS
1.Model DC1
Dimension: LENGTH (IN) x BREATH (IN) x HEIGHT (IN)
Evaporator (cooling unit): 14.5 x 6.5 x 9.0
Condenser assembly (with compressor): 14.5 x 10.0 x 9.0
NOTE: The design may be slightly different from the photo shown because of technical development, and design improvement and evolution.
WARRANTY
~ One year warranty
~ Your money back guarantee if you are not satisfied within 1 month
PRICE
~ Air conditioner @USD474.00 each ex-Miri, Sarawak, Malaysia


Product Description
* Operates on 12 OR 24 volts direct current system from battery or DC generator
* Uses R134a refrigerant which is CFC free
* Current comsumption for 12V system is 7.5 amperes and for 24V system is 3.75 amperes at evaporating temperature of +10 degrees Celcius
* Cooling capacity is about 300 watts
* A typical operating conditions in a room of 6ft by 4ft by 6ft (144 cubic feet) is shown below :
a) The whole system's current consumption : 6.5 to 8 amperes
b) Ambient temperature : 25 to 33 degrees Celcius
c) 40 to 45 degrees Celsius (135 to 152 psig)
d) Evaporating temperature : 8 to 12 degrees Celsius (42 to 53 psig)
e) Room temperature : 23 to 25 deg C
f) Off-coil (breeze blowing from the evaporator) : 18 to 21 deg C
*Dimension : Length (in) x Breath (in) x Height (in)
*Evaporator (cooling unit) : 14.5 x 6.5 x 9.0
*Condenser assembly (with compressor) : 14.5 x 10.0 x 9.0


---------------------------
Dongfar Machinery & Parts Sdn Bhd [Malaysia]
Business Type: Manufacturer
Industry Focus: Air-conditioner , Refrigerator & Freezer
Number of Employees: Less than 5 People
Annual Turnover: Below US$1 Million
Main Market: Worldwide

Company Overview
We are manufacturer of portable 12V DC freezer, refrigerator and air conditioner. The compressor is madeby a renowned compressor manufacturer in Germany. Hence the quality is assured.

Our products, 12V DC freezer, refrigerator and air conditioner, have been exported to Korea, Turkey, UAE, Australia, UK, Canada and the USA.

Currently we are negotiating distributorship in the USA and other parts of the world to provide better after sales service.


We are manufacturer of :
1. 12 and 24 volts dc REFRIGERATOR : DcFRIDGE
2. 12 and 24 volts dc FREEZER : DcFREEZER
3. 12 and 24 volts dc AIR CONDITIONER : DcAIRCON

Using compressor with German technology as the main component. Our compressor with German technology means that you are assured of the quality and trouble-free performance. We hope it gives you years of happy, fault-free and reliable service. We have all the confidence that it will. We have put in hours of patience and skills that go into producing every product that leaves our plant. We back up our product with YOUR MONEY BACK GUARANTEE and ONE YEAR WARRANTY.


Dongfar Machinery & Parts Sdn Bhd is in the business of manufacturing 12 and 24 volt direct current portable freezers and air conditioners. Our products are made locally using the Danfoss compressor and electronic control unit from Germany.

We back all our products with a money back guarantee and a one-year guarantee. With that, you are assured of extreme top quality.


---------------------------
Contact Name: Mr Lee Heng Soon
[email protected]
Tel: 006-03-90747913/90753888
Fax: 006-03-90751688
Address: Lot 19, Lorong 3A, Kawasan Perusahaan Cheras Jaya, Jalan Cheras , 43200 Cheras, Selangor, Malaysia

Contact: Mr Lee Heng Soon
Address: 895, Jalan Krokop 10
City: Miri
Zip/Post Code: 98000
State: Sarawak
Country: Malaysia
Telephone No: 60-85-436433
Fax No: 60-85-436433

Dongfar Machinery And Parts Sdn Bhd
895, Jalan Krokop 10,
Miri, Sarawak
Malaysia 98000
Tel: 6-085-436-433
Fax: 6-085-436-433
Contact: Lee Heng Soon - Managing Director

Company Email: [email protected]
Contact Person: Mr Lee Heng Soon
Contact Person Email: [email protected]
Address: 895 Jalan Krokop 10
Postcode: 98000
City: Miri
State: Sarawak
Country: Malaysia
Telephone No: 60 85 436433
Fax No: 60 85 436433


---------------------------
They also build some very cool looking 12VDC frig and coolers for cheap!

The following sites were culled for the above info:
http://www.mybiz.net/member/dongfar/
http://www.alibaba.com/catalog/121296/12V_DC_Air_Conditioner.html
http://my.ecplaza.net/dongfar/
http://www.ibeli.com/showroom/default.asp?memberid=256
(This next URL is cut in half!- cut and paste them together)
http://www.pickandpost.com.my/dsp_posti ... 6&type=235
&subcat=Common%20Supplies&sec=Electrical/Electronics&pageval=1&searchval=&listval=&location=All&review=0

BoilermakerFan wrote:Two or three at $750 plus shipping from Malaysia? Plus the extra weight at 40lbs a piece, the 5,000 BTU window unit is still the most economical option for now.

Insulate the TD and it won't need three of them. One unit should be enough, for a single person, in a very well insulated TD. Two units would be nice if you have two people in there, or if you have poor insulation. If a TD needs more than 2040 BTUs, there is somthing really wrong with the insualtion!

Also, the unit price listed on another page is only $474. The $750 price is probably the full "retail" "sample unit" price , and the $474 price is probably the real wholesale price we could get them for. Shipping is not that costly, as long as you don't mind a slow boat from China. I'd guess under $50/each.

The real point of interest for me, is this is a possibility to get AC that can be powered by as little as 130 watts of solar panels (about $455 of panels). I think that's amazing. Try to generate the 1100 watts of solar you need for a 5000 BTU model ($3850 of panels, plus a big inverter.) For that matter, just try and find room for that many panels!

Regarding the weight, 40 (or 80) lbs for one (or two) unit(s) isn't that bad, when you think that the 5000 BTU models run about 50 lbs (and the required big inverter runs at least 20 lbs or add the weight of a generator). One of these units is very light in comparison, and two of these units is still not much higher in weight when all things are considered.

If you don't boondock much, plugging in a 5000BTU model is a cheap idea, but I don't plan on ever having access to external power, and I don't like the noise or expense of generators.

I completely agree with your desire to have ac while boondocking. The 5,0000BTU unit is a trade off, having ac requires camping with hook-ups.

I'm engineering a system that would use less than 100 watts/hr. Insulation does not have as large an impact on the TD as it would in a house. I think most people use 1 1/2" foam in the roof and that is the critical area. The difference in heat loss/retention in a 3/4" wall to a 1 1/2" wall along with the additional building challenges it would represent is not high enough for the small area and volume of a TD. The area of the door relative to the volume of air that can escape is very high on a TD.

I think that the small unit you found would work so long as the TD wasn't located in direct sun and the stove wasn't located next to the TD. I think everyone tries to keep their trailer out of the sun in the summer anyways so that might be stating the obvious. The catch is the solar panels would have to be detachable from the trailer so you could position them in the sun at the ideal angle. Keep the TD closed during the day to allow the ac unit to cool it down to your prefered temp. At night it should be able to keep up since the ambient load is reduced.

Interesting concept, the wine cellar coolers I always thought would work however, atleast the ones I had looked at were Peltier cooler systems. They by nature are power hungary (high amp) devices for DC cooling applications. The site did not mention if they were or not. Even split systems are more technical than most people are willing to handle on the installation alone. If I read your post correctly even the DC cooling systems still pull 7 - 8 amps at 12 vdc. does that include the initial surge on compressor start. My 5200 btu A/C unit runs at 4.5 -5 amps with a surge on compressor start of 10 -11 amps. I am not seeing the difference on the actual load on the battery, besides the additional power consumption of invertors to convert to run 120 vac unit which is nominal (about 10% of load). I guess the main question is the money vs. btu's worth the difference vs. 120vac to 12vdc. I think either way battery maintaining is going to be a difficult endeavor, solar or otherwise. The only other way for affordable cooling at 12 vdc is swamp cooling which is efficent at low humidity enviroments. Where did I go wrong, let me know. BTW Amazing effort on the research

Rambling.....

What about one of those walmart 12v travel coolers... pull out the guts, bang a hole in the side of the tear, and have a low draw cooler that should help some.. all for about $60.00...... has this been discussed before?

or better yet, cut off one end of the cooler (the mechanical end) and screw it to the side of the tear, inside or out... (I'm getting desperate, here)....

Yes, it would require a deep cycle marine battery, but would it work...?

Arne we have had a few tv coolers. They suck back the juice in no time and don't cool very well... at least for food.

It would be interesting though to see if it helped at all. I'd consider trying this IF I had electricity. By my calculations last year, our Koolatron would drain the battery in 17.5 hours. The Koolatron draws about 3A. Needless to say we kicked the thing out of the tear...

So questions is... How many CU feet is your tears cabin vs the space in a cooler. How about buy a dozen on sale? Then there is the problem of setting them all up to vent the hot (maybe use warm) air..

One solution is to simply head north, works for us!

Those coolers use Peltier coolers I mention in my previous post. I have two of the (Igloo) coolers. When I read the power consumption(6 amps @ 12vdc) on the units it became clear that they are not a viable option when using battery power. Shore power would be needed,and besides they only cool down 40 - 45 degrees againist outside ambient air tempeture. So if it were 90 degrees outside the internal cooler tempeture would only be 45- 50 degrees againist the volume of the cooler. So it would appear that you would need several (many) to cool the volume of even a teardrop. And the power consumption would huge and kill the battery(ies) pretty darn quick. If that is case, it would be cheaper in the long run to use product like Kooleraire which uses ice as the cooling medium in conjunction with muffin fans in ther setup. I built a bigger unit and it seems to work well in tents and the teardrop. The only problem is using ice, you need a supply. In a pinch the power consumption is minimal (.85 watts)

Goes it get that hot down there? Usually at night here, even if its hot its simply a matter of turning on the ventilator fan for a few minutes and voila, inside temp = outside temp.

I had a digital thermometer in the tear last year that just happened to record min/max temp. it read something like 118F once sitting out on a very hot summer day ! Since the tear was new we got a blast of burning hot air when we opened the door.. I guess it was fumes from the wood finishing.

Hot you say, like the line from that movie "Soldier Story" Hot, this isn't hot, it's Africa hot. If it wasn't the breeze off the oceans on three sides, Florida would be a desert.

HOT !!! well Dave if 3am temps are under 80 degrees we lucky and if the humidity is under 85% its a plus,,the very last thing you want to do is turn on the ventiltor fan,,it just might be only 78 inside,,
summr time camping in the lower 13 except for a few high elevation places is uncomfortable if ya dont have a/c or a huricane blowing,,but when we really suffer is in the winter,,maybe down to freezing and daytime highs only reaching the upper 40s or low 50s,,dang its cold,,time to air out the longjohns, pull out the parkas and get the woolies ready,,winter down here is brutal,,

by the way I dont appreciate the pictres of Fish Pond area,,it sure looks like a super place to visit,,lets see 1200 miles I might make it on a long weekend,,a bit far so I am jelous,,yall have a warm winter

chip

Why shucks partner, y'all don't know what hot is. It gets so hot here in the summer you can fry an egg on the back of your saddle blanket! Last summer it was so hot, I saw a horney toad carrying a canteen!

Bah. Gimme a couple bags of ice, a fan, and that's good enough for me!

http://www.bizstone.com/howto/airconditioner.html

Woody wrote:If I read your post correctly even the DC cooling systems still pull 7 - 8 amps at 12 vdc. does that include the initial surge on compressor start. My 5200 btu A/C unit runs at 4.5 -5 amps with a surge on compressor start of 10 -11 amps

12.5 VDC x 8 Amps = 100 watts
120 VAC x 5 amps = 600 watts

I guess the main question is the money vs. btu's worth the difference vs. 120vac to 12vdc. I think either way battery maintaining is going to be a difficult endeavor, solar or otherwise.

Generating 100 watts is much easier than generating 600 watts, on solar. On generator, I guess it's only a mater of the difference in operating costs of charging up a larger battery bank and generating 6 times more electricity.

My main question will 300 watts/1020 BTUs be enough cooling capacity to hold the temp through a 120 degree day, when I need it the most? It should be, given the appropriate insulation levels are added and adequate thermal mass in the trailer, but that's assuming the AC will still even work at 120 air temp? Other larger ACs would work in these conditions, but how much efficiency do they lose? With only 680 BTUs to play with (max, after my own body's heat load) I need to know if all of a sudden the cooling capacity is half at 120 degrees outside air temp!

An alternative might be having a second unit that is only employed when the single unit just can't keep up with the very hottest of days. Doubles the cost, but also give a backup in case the main unit breaks.

I need a good frig expert to look at the stats on this 12VDC AC unit, and the Danfross stats, and let me know what they think about the efficiency of these units are at different air temps and delta T's (differences in temp between indoor and outdoor air).

I would love the total independence these tiny AC could give me.

The only other way for affordable cooling at 12 vdc is swamp cooling which is efficient at low humidity environments. Where did I go wrong, let me know. BTW Amazing effort on the research

I like swamp coolers, but I don't like the amount of water they consume that I would have to haul around. It's an alternative though, in the dry desert areas I plan to hang around in.