Portable 12V Air Conditioner --Cheap and easy!

Step 10 Test Results

We took the unit out to the truck for a test run when it was well over 90 degrees Fahrenheit (mid to high 30s for Celsius people). My dad set it in the truck and plugged it in, then went back to the house to get a camera. By the time he returned to the truck, the air inside had already dropped below 80, and the air was much drier, making it also feel much cooler.

I attached a PDF of JPEG of a scan of a notecard that my dad took notes on. What it basically says is the following: When the unit was started, the air in the cab was 95 degrees, parked in the shade after a morning of sun,and the outside heat index was 108 degrees. Within five minutes the cab had cooled to 75 degrees, and the air output was 65 degrees. With two quarts of water that had been refrigerated and 8 pounds of ice cubes, the ice had melted after 40 minutes, leaving 50 degree water, with an output of 65 degree air.

In other words, it works! And it works great! On Sunday, August 12 we brought it to Kansas City for a monthly meeting of our electric auto group. WE met in a small meeting room of a library, and ran the air conditioner off a small 12V battery on a table. Many of the members were impressed that they could feel the room getting cooler, and many tried to buy it from us on the spot. We are also in correspondence with an EV owner from Alabama who is eagerly awaiting the publication of this Instructable (I hope). If you're reading this, you know who you are, and I hope you like it.

Comments

[showbizkid83]

Can dry ice be used as a cooling tool.

[jwall18158]

Could it be possible to put an insulated cooler with the pump and ice in it inside your original design and seal the top. Have the hoses coming out of the sealed cooler to the heater core which is still connected to the cover of your orignal design.. I am wondering if your ice would last longer in a sealed or closed cooler. In otherwords, build a cooler with ice, water, and the pump and instal it in another cooler. Also, if you add salt to the water, I think it would lower the temperature or your ice and water combination.(kind of like making homemade ice cream)

[jay_in_hsv]

Great! I spend an hour carefully crafting a reply only to have it eaten by some sort of software glitch. To summarize, changing the rate at which your ice melts simply changes the rate at which the device cools. Reducing GPM thru the heater core or slowing down the rpm of the fans to reduce airflow should also accomplish the same goal. On the other hand, the addition of an additive to the water which would lower its freezing point (antifreeze maybe?) would increase the cooling capacity of a given quantity of ice (assuming you were able to freeze the solution in the first place.)

[Danish M1Garand]

Both of your ideas would work. Land Speed Cars do this with the intercooler being cooled by a ton of ice in the back. Downforce through weight is used rather than aerodynamically as spoiler cause drag. The ton of ice is often boiling at the end of the run. They pump water from the back to the intercooler up front to cool the intake charge. The salt will make the ice melt faster and will allow the coolant liquid to be colder than 0 degrees c. His system is great for a standalone setup. His truck hasn't a heater core anymore and the Military HMMWV belongs to the commander and not the soldier so the troops are prohibited from modifying them. A permanent system would be nice if it were hot several months where you are and you would be allowed to install this.

[desertdog]

Nice instructable.  I have a 1978 MGB electric car.  Most fun I have had in years was building it.  I had pondered the thought of some type of cooling for the occupants but had not done anything yet.  This is just what I needed to get me going on this for next summer.

Are all of your batteries located in the bed of the truck?

[danzajax]

Why not feed the bilge back into your existing heater core? I assume since the vehicle is an EV it is not hooked up any longer. Even if it is, you could easily get a T with a couple valves from the hardware store to switch between heat and cool. Then you could run insulated lines to the cooler and mount it in the bed of your truck for that swank factory look. Nice instructable.

[CameronSS]

It wouldn't be very portable then, now would it? If you feel like poking down through 300 comments to find it, someone did just that in a Honda Civic (I think a Civic...) and put a large ice chest in the back. This truck doesn't have the heater core still in it, so that wasn't an option.

[Rocketmaker10000]

I love this idea. I am building an Electric Car and instead of ripping up the dash of the conversion car I wired up a heating element in the engine bay using a block heater. I am going to T off this system and put a Ice Chest Box with the bilge pump somewhere once I have the Battery Boxes constructed and in place. Then I can determine where it will fit. Great idea!!!

[butthead95]

this thing is sick but u should really make it so no air is running through the cooler ice will last longer

[ericleem]

Maybe hook up one of the fans backward so it blows into the cooler. Or just mount it upside down. Then you have air going into the cooler and then back out. That way you can close the lid, and the air would have to go thru the coil 2 times and cross the ice so it should make for colder air.

[David Cousins]

It doesn't matter that the lid to the cooler is open. The object of this Instructable is to cool the cabin air. So if you open the cooler, the cabin air rushes under the lid, across some ice, and then up through the cold coils. Its getting cold on that trip through the cooler. That's a good thing.

[butthead95]

put the heater core on the outside of cooler with fans on top with hoses thru the lid

[CameronSS]

As I mentioned multiple times in the Instructable and in the comments, the heater core was positioned where it is to allow the condensation to simply drip back into the ice water. If we make another one, we'll probably figure out a different drainage system and put the heater core on top.

[jay_in_hsv]

If you were to eliminate airflow into the water side of the heat exchanger, in effect creating a sealed system, any ideas on what to do with condensation on the air side of the system?

[CameronSS]

It's just water, dribble it into a jar. Hard to be any more specific without knowing the actual setup.

[butthead95]

true true didnt think about that. if you came up with this idea you can defiately figure something out like some sort of casing