Idea for alternative 12v AC?

[dperry324]

Hi guys!

It's getting closer and closer to when I expect to start my build. I think I've decided on minimum size and body style. One thing that I keep coming back to is the A/C system.

Now, I know that many people just wire up a 5,000 BTU Frigidaire wall unit and call it good. That's sounds like the easiest way to go for me, but I keep having thoughts about power usage. My intended purpose may not allow me to plug in and hook up the TD to AC power. Using an inverter off of batter power seems like it would drain the battery all too quickly.

So I'm thinking about some purely 12v cooling alternatives. I've seen many portable swamp coolers that use coleman or igloo style coolers combined with DC fans to create the cool, but that's only good for a few hours too, up until when the ice needs to be replaced.

I have an idea for creating a closed-system cooler, using condenser and evaporation coils, 12v fans and 12v submersible fountain pumps. I will have to do some extensive testing on that last option, so I was thinking if something similar has already been done.

What I've found is that there are numerous electric, portable coolers on the market. They typically plug into the car's cigarette lighter for power.

http://www.walmart.com/ip/Coleman-40-Qu ... r/21156022

I'm wondering if one of the coolers can be modified like the other swap coolers and be used in a similar fashion. Has anybody tried such a thing? Is the cooling power good enough? Is the battery drain low enough that it could keep the cooler going all night?

Thoughts?

[KennethW]

A battery does not have the power to run any AC that would be big enough to do any good. The bucket of ice with a fan is not a swamp cooler. A swamp(evaporation)cooler is wet mat with air puller thru it. I build one but did not get to test it (no hot weather) It is just a box mounted in the window with a mat with a small water pump wetting the mat. The water that runs out the mat is returner to the bucket. The ceiling fan draws the air thru the mat in to the teardrop and out the top. here is a picture.
click to enlarge

Here is the swamp cooler I based mine on.

http://www.builditsolar.com/Projects/Co ... Cooler.htm

Any Questions?

[MtnDon]

The cooler that was linked to is a thermoelectric type. A heavy power user.

[Shadow Catcher]

Kennith is correct AC demands much more power than you have with out a generator. I have played around with the idea of powering an automotive AC compressor with a small gas engine which you could do but the level of complication was daunting.

[dperry324]

A battery does not have the power to run any AC that would be big enough to do any good. The bucket of ice with a fan is not a swamp cooler. A swamp(evaporation)cooler is wet mat with air puller thru it. I build one but did not get to test it (no hot weather) It is just a box mounted in the window with a mat with a small water pump wetting the mat. The water that runs out the mat is returner to the bucket. The ceiling fan draws the air thru the mat in to the teardrop and out the top. here is a picture.
click to enlarge

Here is the swamp cooler I based mine on.

http://www.builditsolar.com/Projects/Co ... Cooler.htm

Any Questions?

That is a very good design. I'll take that into consideration.

[mrwall1]

That looks pretty interesting! We just used the fantastic fan and had no problem being cool all night.. Now we do not get the extreme heat up here in Western Washington like the rest of the Country, but it was in the high 90's one of the weekends... and had no issues... we keep the windows open on the doors... and keep the fan exhausting all day and night.
mike

[MtnDon]

Note that there are 12 and 24 VDC A/C's made for the trucking industry. They use the same Danfoss type compressors as the 12/24 VDC refrigerators like Truckfridge, Novacool, ARB, Engel. Pricey but about as efficient as you can get running on 12/24 VDC.

[noseoil]

I've looked into it, thought about alternatives and on my build I've decided to use the 5000 BTU AC unit & either shore power or a small portable generator. A 12v storage battery just doesn't have the capacity to run an AC unit on 115v power for any length of time. 20% of the power is lost when converting from DC to AC power to begin with. A small AC unit needs about 5 amps at 115v just to run, that's over 500 watts! Convert that to 12v through an inverter and you would be sucking a battery dry before the trailer is even cooled off (with the inverter it would be about a 600 watt load).

I figure an AC unit is great to have, but it needs an extension cord or a minimum of 1000 watts from the generator to be safe. I'm planning on getting a 2000 watt Honda and figuring it's done at that point. A battery & solar panel is great for LED lights, phone charging & entertainment, but going much past that is asking for trouble, or adding huge amounts of weight in storage capacity for enough battery power. Just my 2 cents worth.....

[Vedette]

Everyone seems to be trying to find the "IDEAL" AC Unit for Teardrops!
And he who comes up with one may have enough clients to actually make some money off or such a solution???
Just saying!
We are all waiting!
Good Roads
Brian & Sandi

[mustangcats]

I always thought camping was about being out in nature and going without modern conveniences, especially those that run on electricity. But if you must have A/C, then a 120 volt air conditioner is the only way you will be able to cool a trailer and be happy. It takes a lot of constant, cold air to keep a space cool...and you aren't going to get that from a bucket of ice or any of those 12 volt coolers. Get the 120 volt air conditioner and count on having either shore power or a generator to run it. If you don't have either, then you'll just have to "rough it". The next best alternative is to have some good battery operated fans. I have an O2 fan that moves a lot of air and runs for many, many hours on D cell batteries.

[GuitarPhotog]

Remember also that an evaporative (swamp) cooler is effective only in low humidity (<40%) conditions. The are totally ineffective in high (>70%) humidity conditions.

Great for the desert but not so much for places like Florida.

<Chas>

[jstrubberg]

Question #1

What part of the country do you camp in?

A swamp cooler can do the job, but only in low humidity areas. Anywhere the humidity routinely runs over 50% or so during the day, you're not going to get much cooling from a swamp cooler.

[Engineer Guy]

This is 'just' a Fan, but impressed me the other day. We were Camping, and had to run the Pooch to a local Vet to have his Eye checked out. All is fine. The Exam Room was mighty hot. She clicked on this Fan, and it did an impressive job cooling the Room. If you've got a small 120 VAC Inverter going p/t anyway, this might work.

Lasko Fan

Sidenote: While Camping, we use this Lasko Heater w/built-in Thermostat if on 120 VAC Service. Intrinsically safe.

Lasko Heater From Wally World

$12/night [Off-Peak Season] w/30 or 50 Amp Electrical. Da Wife appreciates the spotless Water Flush Toilets, even though she's no Princess. Amazing Skies @ ~7,540'.

Elk Creek Campground

[tony.latham]

I'm not trying to hijack this thread, but it is reminding me why I'm glad I don't live in (and camp) in Texas or anywhere else that is hotter than a dutch oven. I can't imagine limiting my camping to someplace with a 120V hookup or having to run a generator.


That old photo is a bit tongue-in-cheek for this thread, but here in Idaho, I really like my Fantastic fan. It's all that's needed up here, even when it's hot.

But good luck with this challenge!

Tony

[wincrasher]

Any swamp type cooler is just a waste in the southern states. Far too humid for it to work.

Any AC unit on 110v power is just too many amps to run on DC. A 10 amp AC unit is going to be 100 ah roughly on DC to run. You just can't carry enough batteries or have room for a large enough inverter to run it.

There are some DC air conditioner units for marine service, but they are very costly and you still don't have enough battery capacity.

So your alternatives are a making a window air conditioner on 110v shore power or with generator, or an RV type air conditioner on 110v. That really is it.

The Fridgedair I believe is only 7-8 amps and can work on a small inverter generator like the honda or yamaha for not a lot of money. There are a bunch of ways to build this into a trailer, so I'd put my efforts on the best way to do that in your rig and not waste time chasing these other pipe dreams.