12 volt air conditioner
in 2011 I built a Tear drop trailer (TD) similar to this http://www.instructables.com/id/Teardrop-Travel-Trailer/ , most TD campers carry some sort of air conditioner to deal with the hot weather. In dry areas of the country a swamp cooler works fine as blowing a fan over a block of ice will cool the air and any moisture picked up from the ice will feel nice.
In humid areas of the country a swamp cooler just adds to the misery, I remember spending a few weeks in Mena, AR at a paint shop. At 97 F and 90% humidity the sanding crew was dying from the heat in the shade, so the boss went out and borrowed or rented a swamp cooler. As I was just observing our aircraft being painted I could sit right in front of the swamp cooler all day, from walking around I discovered that the cooler feeling air only lasted about 4-6 feet from the cooler, after that the breeze felt ok and more than 10 feet away all you got was the noise of the huge fan.
The swamp cooler was about 6 feet square, it had a 5 foot tall fan blowing through some sort of paper strips that were being saturated with water being pumped over them from a large tank in the base. the base tank needed to be hooked to a garden hose to keep it from going dry. For all the water being evaporated I think the swamp cooler just made it worse inside the paint shop, and it made the paint jobs have problems.
the main reason air conditioning feels so nice in humid areas is that the air conditioner removes quite a bit of water vapor, dry air allows you to sweat, which is the way your skin gets rid of extra heat. Just look underneath your car or air conditioner and you will see a puddle on a hot humid day. In fact modern cars run the air conditioner on low when you select "defrost" to remove the excess moisture.
For those of us who don't want to lug an air conditioner in our trailers (or tents), and where a swamp cooler won't work, or where you would need a 50 mile extension cord or deal with a generator, I took a few different ideas from Instructables.com and put them together in my car.
Being from Maine, I bought a new car without air conditioning, since we only need AC for a week or two up here almost 25% of cars are sold without AC, saving about $800. Since then I got a job in central NH where the weather is much hotter than coastal Maine. I decided I needed some AC.
I bought a used heater core off of fleabay for $25, a cooler that would fit between my kids booster seats in the back seat $35, two computer cooling fans for $15 fleabay, and a 12 volt live bait well pump $30 wallyworld boating isle. When assembled as shown the heater core blew cold air on the back of my head, but was not enough to cool off my car with it's untinted windows and blazing sun shinning in. I also thought my heater core was garbage as water streamed from it while it was running, after pressure checking it I found it was still good, I had been condensing tons of water out of the humid air.
While this was a failure, I learned a few things, that if applied to a well insulated area (inside my TD which if you made it a cube would only be 160 cubic feet (5' W X 8' L X 4' H)) will work as long as enough ice is used.
I modified my "air conditioner" into a "body cooler" and now it works great, and the ice lasts forever.
In humid areas of the country a swamp cooler just adds to the misery, I remember spending a few weeks in Mena, AR at a paint shop. At 97 F and 90% humidity the sanding crew was dying from the heat in the shade, so the boss went out and borrowed or rented a swamp cooler. As I was just observing our aircraft being painted I could sit right in front of the swamp cooler all day, from walking around I discovered that the cooler feeling air only lasted about 4-6 feet from the cooler, after that the breeze felt ok and more than 10 feet away all you got was the noise of the huge fan.
The swamp cooler was about 6 feet square, it had a 5 foot tall fan blowing through some sort of paper strips that were being saturated with water being pumped over them from a large tank in the base. the base tank needed to be hooked to a garden hose to keep it from going dry. For all the water being evaporated I think the swamp cooler just made it worse inside the paint shop, and it made the paint jobs have problems.
the main reason air conditioning feels so nice in humid areas is that the air conditioner removes quite a bit of water vapor, dry air allows you to sweat, which is the way your skin gets rid of extra heat. Just look underneath your car or air conditioner and you will see a puddle on a hot humid day. In fact modern cars run the air conditioner on low when you select "defrost" to remove the excess moisture.
For those of us who don't want to lug an air conditioner in our trailers (or tents), and where a swamp cooler won't work, or where you would need a 50 mile extension cord or deal with a generator, I took a few different ideas from Instructables.com and put them together in my car.
Being from Maine, I bought a new car without air conditioning, since we only need AC for a week or two up here almost 25% of cars are sold without AC, saving about $800. Since then I got a job in central NH where the weather is much hotter than coastal Maine. I decided I needed some AC.
I bought a used heater core off of fleabay for $25, a cooler that would fit between my kids booster seats in the back seat $35, two computer cooling fans for $15 fleabay, and a 12 volt live bait well pump $30 wallyworld boating isle. When assembled as shown the heater core blew cold air on the back of my head, but was not enough to cool off my car with it's untinted windows and blazing sun shinning in. I also thought my heater core was garbage as water streamed from it while it was running, after pressure checking it I found it was still good, I had been condensing tons of water out of the humid air.
While this was a failure, I learned a few things, that if applied to a well insulated area (inside my TD which if you made it a cube would only be 160 cubic feet (5' W X 8' L X 4' H)) will work as long as enough ice is used.
I modified my "air conditioner" into a "body cooler" and now it works great, and the ice lasts forever.
Step 1What are you hacking together?
to build a 12 volt air conditioner or body cooler you will need mostly the same items..
-flexible hose and clamps
-12 volt bait well pump (I bought the 500 gph model, way over kill on the flow rate but cheap)
-wiring
-cigar lighter plug
-largest cooler you can fit in the area it will sit. (air conditioners are rated in BTU's, the smallest ones for sale cheap are the 5,000 BTU ones, house and larger ones are rated in tons, this air conditioner will depend on how much ice you can put in it) I found the "marine" coolers the best for what I needed as they tend to be all white (less solar heat gain) and much more rectangular with less bulk (takes up space) mine also has large easy to hold handles (easy to strap into the seat belt in the car, and easy to carry full of ice and water) it also has an external hinge, most hinged lid designs have a air leak around the hinge, the external hinge type have a lid that will lock in place even if you remove the hinges.
-zip ties
for a 12 volt air conditioner you will also need:
-a car heater core (mine was from a jeep Cherokee, I figured one from an SUV or van would have a larger heat exchanging area than one for a small car)
-as many 12 volt fans as it will take to cover the grid section of the heater core.
-12 volt switches or a house thermostat (if you want the fan to go on and off at a certain temp)
-a drip pan that is larger than the heater core and some sort of drain line to carry condensation back to the cooler
for a body cooler:
-small diameter PEX plumbing and fittings (I used 3/8" but now I see 1/4" in some hardware stores)
Tools:
drill and hole drills
screw drivers
wire crimpers
pex ring crimpers (if you use pex) (my crimper is a two part C shaped set of jaws that you squeeze using vice grips, it has spots in it to crimp 3/8", 1/2", 3/4", and 1" pex copper crimp rings.
-flexible hose and clamps
-12 volt bait well pump (I bought the 500 gph model, way over kill on the flow rate but cheap)
-wiring
-cigar lighter plug
-largest cooler you can fit in the area it will sit. (air conditioners are rated in BTU's, the smallest ones for sale cheap are the 5,000 BTU ones, house and larger ones are rated in tons, this air conditioner will depend on how much ice you can put in it) I found the "marine" coolers the best for what I needed as they tend to be all white (less solar heat gain) and much more rectangular with less bulk (takes up space) mine also has large easy to hold handles (easy to strap into the seat belt in the car, and easy to carry full of ice and water) it also has an external hinge, most hinged lid designs have a air leak around the hinge, the external hinge type have a lid that will lock in place even if you remove the hinges.
-zip ties
for a 12 volt air conditioner you will also need:
-a car heater core (mine was from a jeep Cherokee, I figured one from an SUV or van would have a larger heat exchanging area than one for a small car)
-as many 12 volt fans as it will take to cover the grid section of the heater core.
-12 volt switches or a house thermostat (if you want the fan to go on and off at a certain temp)
-a drip pan that is larger than the heater core and some sort of drain line to carry condensation back to the cooler
for a body cooler:
-small diameter PEX plumbing and fittings (I used 3/8" but now I see 1/4" in some hardware stores)
Tools:
drill and hole drills
screw drivers
wire crimpers
pex ring crimpers (if you use pex) (my crimper is a two part C shaped set of jaws that you squeeze using vice grips, it has spots in it to crimp 3/8", 1/2", 3/4", and 1" pex copper crimp rings.
12 volt air conditioner
Step 2Making your heatsink
just like dark is the absence of light, cold is the absence of heat.
- Remove the hinges from the cooler lid, mine came off with screws so it was easy. You want the pump, wiring, and return tube, all connected to the lid so it can be left in place while you go fill the cooler with ice and water.
-Put the 12 volt pump in one corner of the cooler, if the cooler will be sitting on a seat or other tilted area put the pump at the lowest end.
-connect the flexible tubing to the outlet nipple of the pump and secure it as needed (the pump I have has the nipple coming out the side, I used clear plastic tubing to connect on to the nipple, and then a plastic pex 90 degree elbow to run my tubing vertically up to the cooler lid.
-mark the lid of the cooler where you want to run your tubing through it.
-drill the smallest hole you can get the tubing through to minimize air leaks.
-drill another hole in the lid, right next to the first one, or at the opposite end, it is more convenient for me to have both hoses next to each other, however to make sure the water is going through all of the ice I added a 90 degree elbow to the hose to shoot the water at the opposite end of the cooler from the pump.
-seal the holes in the cooler lid with RTV
- Remove the hinges from the cooler lid, mine came off with screws so it was easy. You want the pump, wiring, and return tube, all connected to the lid so it can be left in place while you go fill the cooler with ice and water.
-Put the 12 volt pump in one corner of the cooler, if the cooler will be sitting on a seat or other tilted area put the pump at the lowest end.
-connect the flexible tubing to the outlet nipple of the pump and secure it as needed (the pump I have has the nipple coming out the side, I used clear plastic tubing to connect on to the nipple, and then a plastic pex 90 degree elbow to run my tubing vertically up to the cooler lid.
-mark the lid of the cooler where you want to run your tubing through it.
-drill the smallest hole you can get the tubing through to minimize air leaks.
-drill another hole in the lid, right next to the first one, or at the opposite end, it is more convenient for me to have both hoses next to each other, however to make sure the water is going through all of the ice I added a 90 degree elbow to the hose to shoot the water at the opposite end of the cooler from the pump.
-seal the holes in the cooler lid with RTV
Step 3Cooling off a tear drop trailer
-install the heater core where you want it, I plan on having mine installed near the top of the galley wall in the galley, with a vent into the TD sleeping compartment.
-mount your 12 volt fans so they blow through the heater core. I plan on one fan bringing in outside air all the time, and the other recirculating air from inside the TD.
-mount a drip pan underneath the heater core with a drain line back to the cooler.
-run the wires from your 12 volt power source to a switch or two. I plan on having my TD have two fans both running continuously, one bringing in fresh air the other recirculating TD bedroom air, and a wall thermostat switching the 12 volt pump on and off. This may exceed the amps rating for a normal wall thermostat but they also sell 120/220 V wall thermostats that will work.
-run the plumbing from the heater core to the cooler and clamp the ends if needed.
-zip tie everything in place as needed.
-fill the cooler with ice or ice packs, I use juice bottles full of water (fill 3/4 full, dump in salt and shake until the water won't absorb any more, put the lid on and freeze with the bottle on its side) leave a space for the pump (I plan on making some sort of baffle to keep ice away from the pump )
-put in enough water to cover the top of the pump.
-put the the cooler back together, turn it on, check for leaks.
-enjoy hours of cool air in your TD.
since a TD is mostly used inside for sleeping, a cooler full of ice should last the night, however you will probably have to refill the ice and dump out most of the water from the night before. Since most campgrounds, and gas stations have ice for sale this shouldn't be too hard.
I have posted this idea on tnttt.com and one guy has tried it, http://www.tnttt.com/viewtopic.php?f=29&t=18104&hilit=rowerwet&start=15 the guy who tried it is near the bottom of page 2 of the thread
his quote " I used 10lbs of ice and it lasted about 5 hours at 88 degree's outside, my Tear maintained 76 degrees." He goes on to give ideas on how he wants to improve the design using a copper coil inside the cooler instead of a large bath of water, to do that though would require some sort of reservoir for expansion of the water, not hard, just a little more details, is all.
just like my other I'ble on how to heat a TD or tent off the grid, this gives a way to cool a TD off the grid. In fact ice was around a long time before refrigerators, my parents house is built in the area that an ice house once stood hundreds of years ago. During the New England winter ice was cut out of the pond behind their house and packed in straw and saw dust in double walled ice barns, the ice was even shipped all around the world in old sailing ships packed in straw and sawdust to be sold.
-mount your 12 volt fans so they blow through the heater core. I plan on one fan bringing in outside air all the time, and the other recirculating air from inside the TD.
-mount a drip pan underneath the heater core with a drain line back to the cooler.
-run the wires from your 12 volt power source to a switch or two. I plan on having my TD have two fans both running continuously, one bringing in fresh air the other recirculating TD bedroom air, and a wall thermostat switching the 12 volt pump on and off. This may exceed the amps rating for a normal wall thermostat but they also sell 120/220 V wall thermostats that will work.
-run the plumbing from the heater core to the cooler and clamp the ends if needed.
-zip tie everything in place as needed.
-fill the cooler with ice or ice packs, I use juice bottles full of water (fill 3/4 full, dump in salt and shake until the water won't absorb any more, put the lid on and freeze with the bottle on its side) leave a space for the pump (I plan on making some sort of baffle to keep ice away from the pump )
-put in enough water to cover the top of the pump.
-put the the cooler back together, turn it on, check for leaks.
-enjoy hours of cool air in your TD.
since a TD is mostly used inside for sleeping, a cooler full of ice should last the night, however you will probably have to refill the ice and dump out most of the water from the night before. Since most campgrounds, and gas stations have ice for sale this shouldn't be too hard.
I have posted this idea on tnttt.com and one guy has tried it, http://www.tnttt.com/viewtopic.php?f=29&t=18104&hilit=rowerwet&start=15 the guy who tried it is near the bottom of page 2 of the thread
his quote " I used 10lbs of ice and it lasted about 5 hours at 88 degree's outside, my Tear maintained 76 degrees." He goes on to give ideas on how he wants to improve the design using a copper coil inside the cooler instead of a large bath of water, to do that though would require some sort of reservoir for expansion of the water, not hard, just a little more details, is all.
just like my other I'ble on how to heat a TD or tent off the grid, this gives a way to cool a TD off the grid. In fact ice was around a long time before refrigerators, my parents house is built in the area that an ice house once stood hundreds of years ago. During the New England winter ice was cut out of the pond behind their house and packed in straw and saw dust in double walled ice barns, the ice was even shipped all around the world in old sailing ships packed in straw and sawdust to be sold.
Step 4The body cooler
this is my current design instead of air conditioning in my car, it is a direct copy of this I'ble http://www.instructables.com/id/Too-Hot-Remove-heat-from-your-body-with-the-Back-/ only mine uses pex as the heat exchanger, this works very well, almost too well, I have had to unplug it more than once while driving on very hot days, as I found I wasn't sweating anymore and was starting to feel a little sick to the stomach. a timer circuit or some sort of clip on body thermostat might be a good idea.
IF YOU HAVE CIRCULATION PROBLEMS THIS IS NOT A GOOD IDEA FOR YOU! IT WORKS TOO WELL AND COULD KILL OR BADLY HURT YOU.
After my heater core Air conditioner idea failed due to the heat coming in through the window glass, I took the heater core off of the cooler and made a back heat exchanger this way:
-measure the length of the nipples on the T fittings with the tips touching,
-cut a short piece of PEX to cover that length and install it on the nipples with a PEX lock ring.
-crimp the ring in place with the pex crimper.
-continue the string of T fittings with all of the T lower legs pointing up until you reach the width of the seat back it will be installed on.
-for the last pipe you need a 90 degree fitting instead of a T fitting.
-count the number of T's and put another string together that matches the first string you made
-measure the height of the seat back and cut the small diameter PEX tubing to length
-install the PEX tubing to the T legs to connect the upper and lower runs, with the exit for the water at the top opposite the in for the water at the bottom.
-I used two 90 degree PEX fittings at the top to turn the water return 180 degrees behind the headrest of the car seat to lock it in place.
-connect the lower and upper supply/return lines to the flexible tubing coming from the cooler
-run the wires from the cigar lighter plug to the pump. an inline switch might be nice as it would save plugging and unplugging the cigar lighter every time. my cigar lighter plug has an LED in it to let me know it is getting power. The first time I used it I bumped the cord and the fuse inside the plug blew, since I knew my cell phone charger still worked that meant the plug had the open, which turned out to be the fuse.
-fill the cooler with ice and just enough water to cover the pump
-put the pump in the cooler so it is at the back in most cars, as the seat slopes toward the back.
-this design is so efficient that you could easily us a very small cooler, or do all of the seats in the car, and since the pump is rated for 500 gph it would handle all four, just install a simple in line ball valve for each seat back to regulate flow if no one is sitting there.
this set up works great and you really don't notice the pipes as the seat back lets them sink in.
-I like having clear plastic supply lines also as they let me see that water is flowing, however they are not rigid enough to keep from being collapsed by my weight against the seat back, PEX is very rigid, I could probably stand on a PEX pipe, and even if it did collapse it would just snap back.
running the water from the bottom of the seat back to the top ensures that it is always full, if it ran from the top down the water could drain through the first few tubes and leave the last few empty.
IF YOU HAVE CIRCULATION PROBLEMS THIS IS NOT A GOOD IDEA FOR YOU! IT WORKS TOO WELL AND COULD KILL OR BADLY HURT YOU.
After my heater core Air conditioner idea failed due to the heat coming in through the window glass, I took the heater core off of the cooler and made a back heat exchanger this way:
-measure the length of the nipples on the T fittings with the tips touching,
-cut a short piece of PEX to cover that length and install it on the nipples with a PEX lock ring.
-crimp the ring in place with the pex crimper.
-continue the string of T fittings with all of the T lower legs pointing up until you reach the width of the seat back it will be installed on.
-for the last pipe you need a 90 degree fitting instead of a T fitting.
-count the number of T's and put another string together that matches the first string you made
-measure the height of the seat back and cut the small diameter PEX tubing to length
-install the PEX tubing to the T legs to connect the upper and lower runs, with the exit for the water at the top opposite the in for the water at the bottom.
-I used two 90 degree PEX fittings at the top to turn the water return 180 degrees behind the headrest of the car seat to lock it in place.
-connect the lower and upper supply/return lines to the flexible tubing coming from the cooler
-run the wires from the cigar lighter plug to the pump. an inline switch might be nice as it would save plugging and unplugging the cigar lighter every time. my cigar lighter plug has an LED in it to let me know it is getting power. The first time I used it I bumped the cord and the fuse inside the plug blew, since I knew my cell phone charger still worked that meant the plug had the open, which turned out to be the fuse.
-fill the cooler with ice and just enough water to cover the pump
-put the pump in the cooler so it is at the back in most cars, as the seat slopes toward the back.
-this design is so efficient that you could easily us a very small cooler, or do all of the seats in the car, and since the pump is rated for 500 gph it would handle all four, just install a simple in line ball valve for each seat back to regulate flow if no one is sitting there.
this set up works great and you really don't notice the pipes as the seat back lets them sink in.
-I like having clear plastic supply lines also as they let me see that water is flowing, however they are not rigid enough to keep from being collapsed by my weight against the seat back, PEX is very rigid, I could probably stand on a PEX pipe, and even if it did collapse it would just snap back.
running the water from the bottom of the seat back to the top ensures that it is always full, if it ran from the top down the water could drain through the first few tubes and leave the last few empty.
Portable 12V Air Conditioner --Cheap and easy!
This project is my dad's $10 solution to a $500 solution to a $25,000 problem. As I have previously mentioned around the site, my Dad owns an electric 1979 Ford Courier pickup, and is cool enough to let me drive it around. We absolutely love it, and wouldn't trade it for a Tesla Roadster, but one of the few problems with electric cars is heating and cooling. In a gas car, heat is provided by the 80% of the gas that is wasted as heat, and air conditioning is provided by a crankshaft-driven compressor system. Many EVs use hair dryer elements and fans for heat, and some, ours included, feature a powerful gasoline-burning heater.
(Update from 4-22-08: I'd forgotten that I mentioned the gas heater on here. Last fall the gas tank and heater were removed, and a ceramic heater was built in. It works great, although not quite as fast, and doesn't use gas.)
However, air conditioning is trickier because the shaft of an electric motor doesn't always spin. Some have used a compressor driven by the motor shaft anyway, while others have turned a compressor using a separate motor. Finally, my dad came up with part of the concept for this system. It pumps ice water through an evaporator core, which has fans that blow air through it. It is very simple, but we found what we were looking for at Sporty's Pilot Shop. They sell air conditioners built into ice chests for prices ranging from $475 for a basic model to $625 for a 24V, dual fan model.There is also an ArcticAir unit for $4750 with a full compressor unit. However, we like our $10 version better. I saw the ArcticAir display at EAA AirVenture Oshkosh this summer, and our unit is more compact and puts out cooler air. All you need is materials, basic construction/assembly and wiring skills, and a bag of ice. Let's go!
(Update from 4-22-08: I'd forgotten that I mentioned the gas heater on here. Last fall the gas tank and heater were removed, and a ceramic heater was built in. It works great, although not quite as fast, and doesn't use gas.)
However, air conditioning is trickier because the shaft of an electric motor doesn't always spin. Some have used a compressor driven by the motor shaft anyway, while others have turned a compressor using a separate motor. Finally, my dad came up with part of the concept for this system. It pumps ice water through an evaporator core, which has fans that blow air through it. It is very simple, but we found what we were looking for at Sporty's Pilot Shop. They sell air conditioners built into ice chests for prices ranging from $475 for a basic model to $625 for a 24V, dual fan model.There is also an ArcticAir unit for $4750 with a full compressor unit. However, we like our $10 version better. I saw the ArcticAir display at EAA AirVenture Oshkosh this summer, and our unit is more compact and puts out cooler air. All you need is materials, basic construction/assembly and wiring skills, and a bag of ice. Let's go!
Step 1Background and How it Works
This project is very similar to the ArcticAir Package Unit. In fact, I attached two pictures of it I took at AirVenture this past summer. It looks almost identical to ours, and we built this without ever seeing a picture of the inside! The basic concept is to use a boating bilge pump to circulate iced water through a heater core, then use 12V fans to blow air through that core, which cools the air and pulls out water through condensation.
Advantages: Very compact and portable, lightweight without the ice, no environmentally not-so-friendly chlorofluorocarbons, hydrogenated chlorofluorocarbons, or hydrofluorocarbons, very quiet, and operates off 12VDC, AKA a cigarette lighter. The only disadvantage is that it the ice will melt after 30-60 minutes of operation, depending on the size of your cooler. However, it was built for an EV, so we are only ever out for an hour or two maximum, and the ice lasts longer when it's not running. The third image on this step shows the operation. Have I convinced you to build one yet?
Advantages: Very compact and portable, lightweight without the ice, no environmentally not-so-friendly chlorofluorocarbons, hydrogenated chlorofluorocarbons, or hydrofluorocarbons, very quiet, and operates off 12VDC, AKA a cigarette lighter. The only disadvantage is that it the ice will melt after 30-60 minutes of operation, depending on the size of your cooler. However, it was built for an EV, so we are only ever out for an hour or two maximum, and the ice lasts longer when it's not running. The third image on this step shows the operation. Have I convinced you to build one yet?
You can't very well build this without materials to build it with, can you? I have included the prices we paid for them in italics, as well as prices you might pay and places to get them.
Materials:
Ice Chest-free, had it on hand If at all possible, get one with a hinged lid. Free from a storage shed or a dumpster. Or, the Igloo Ice Cube 14 looks like it would work,well, as do the Cool 16 and the MaxCold 24. We used an old 12 quart cooler, and it fit a 7 pound bag of ice.
Heater Core-free, salvaged from a '77 VW Rabbit we're parting out You can find these on eBay for 99 cents to $20, or from an auto store for around 20 bucks, or at an auto salvage yard. Also, I haven't tried it, but Ufixitautoparts sells heater cores for under 5 bucks apiece.
Box Fans and Blade Guards-free, from stock in basement They're sold out of $5 120mm 12VDC fans at All Electronics, but Jameco carries these for $12.95 each. Newegg has a nice assortment, too. Under $10 on eBay.
Bilge Pump-$10.44 for a 500GPH unit at Wal-Mart The Attwood V500 was at our Wal-Mart for $10.44-you can get a similar pump for under $10 on eBay.
Hose-free, had it in stock Ours came from an auto-parts store, but it can be found at hardware and auto-parts stores for a dollar or so for a few feet.
12V plug-free, chopped off a car accessory Cut one off an old phone charger or other device, or $5 at Radio Shack, or $3.75 at All Electronics.
Caulking-free, from the stock in the shop Can be found near the bilge pump, or from a hardware store. A couple bucks.
Piano hinge (depending on cooler)-free, in stock Only necessary if your cooler isn't hinged. A couple bucks at the hardware store.
Inner tube piece (optional)-free, blown tube You may or may not need this-see step 7. If you do, use a blown one, or another piece of rubber, or come up with a substitute. You did save the last blown tube for future projects, didn't you? A couple bucks, tops.
Assorted wire, wire nuts, and screws-free, in stock Depends on what you have in stock and where you get it. It's all at the hardware store, too.
Ice-free, freezer's ice maker If you need me to tell you where to get ice, you shouldn't be doing this project.
Tools:
Screwdrivers
Drill
Cutting devices
Obligatory safety spiel: Cutting devices cut. Don't cut yourself on them. Drills drill. Don't drill a hole in yourself, my dad says it hurt when he did it once. Screwdrivers don't really do anything, but don't throw them into running jet turbine engines. 12V doesn't do much, but watch out. Oh, and wear safety glasses while you're at it.
Materials:
Ice Chest-free, had it on hand If at all possible, get one with a hinged lid. Free from a storage shed or a dumpster. Or, the Igloo Ice Cube 14 looks like it would work,well, as do the Cool 16 and the MaxCold 24. We used an old 12 quart cooler, and it fit a 7 pound bag of ice.
Heater Core-free, salvaged from a '77 VW Rabbit we're parting out You can find these on eBay for 99 cents to $20, or from an auto store for around 20 bucks, or at an auto salvage yard.
Box Fans and Blade Guards-free, from stock in basement They're sold out of $5 120mm 12VDC fans at All Electronics, but Jameco carries these for $12.95 each. Newegg has a nice assortment, too. Under $10 on eBay.
Bilge Pump-$10.44 for a 500GPH unit at Wal-Mart The Attwood V500 was at our Wal-Mart for $10.44-you can get a similar pump for under $10 on eBay.
Hose-free, had it in stock Ours came from an auto-parts store, but it can be found at hardware and auto-parts stores for a dollar or so for a few feet.
12V plug-free, chopped off a car accessory Cut one off an old phone charger or other device, or $5 at Radio Shack, or $3.75 at All Electronics.
Caulking-free, from the stock in the shop Can be found near the bilge pump, or from a hardware store. A couple bucks.
Piano hinge (depending on cooler)-free, in stock Only necessary if your cooler isn't hinged. A couple bucks at the hardware store.
Inner tube piece (optional)-free, blown tube You may or may not need this-see step 7. If you do, use a blown one, or another piece of rubber, or come up with a substitute. You did save the last blown tube for future projects, didn't you? A couple bucks, tops.
Assorted wire, wire nuts, and screws-free, in stock Depends on what you have in stock and where you get it. It's all at the hardware store, too.
Ice-free, freezer's ice maker If you need me to tell you where to get ice, you shouldn't be doing this project.
Tools:
Screwdrivers
Drill
Cutting devices
Obligatory safety spiel: Cutting devices cut. Don't cut yourself on them. Drills drill. Don't drill a hole in yourself, my dad says it hurt when he did it once. Screwdrivers don't really do anything, but don't throw them into running jet turbine engines. 12V doesn't do much, but watch out. Oh, and wear safety glasses while you're at it.
An ice chest/cooler has a double lid with a cavity. This is convenient because we can cut separate holes for the fan and heater core.
On the underside of the lid, mark the outline of the heater core, then go in about a quarter inch and cut out a rectangular hole through ONLY the first layer. This will allow airflow through the core, but still make it easy to attach.
Next, you will need to mark the inside of the fans and cut out two circular holes. We originally planned to use a hole saw to cut the holes, but found that we didn't have a bit that big, so we chucked a saw blade into the Dremel Rotary tool and zipped it out, of course wearing safety glasses (hint hint).
Tada! You now have a rectangle on the inside and two circles on the outside. Now that you cut out these lovely holes, lets fill them in.
On the underside of the lid, mark the outline of the heater core, then go in about a quarter inch and cut out a rectangular hole through ONLY the first layer. This will allow airflow through the core, but still make it easy to attach.
Next, you will need to mark the inside of the fans and cut out two circular holes. We originally planned to use a hole saw to cut the holes, but found that we didn't have a bit that big, so we chucked a saw blade into the Dremel Rotary tool and zipped it out, of course wearing safety glasses (hint hint).
Tada! You now have a rectangle on the inside and two circles on the outside. Now that you cut out these lovely holes, lets fill them in.
Step 4Attach Heater Core and Fans
The next step is to attach the fans. This is fairly straightforward--simply drill a small pilot hole at each corner of each fan, and put a small screw through the bottom hole into the plastic lid. Don't block the top hole if you want to add a fan guard later.
To attach the heater core, we used silicone caulk. A bead all the way around seals the lid and provides plenty of bonding force to hold the heater core in place. Make sure to get the core centered, straight, and with the nozzles pointing in. If your lid is hinged, you will want to do a test fit before attaching the core to ensure that the nozzles clear the edges. If your lid is not hinged, it may be easier to attach it first. We ended up cutting the output off to make it fit better.
To attach the heater core, we used silicone caulk. A bead all the way around seals the lid and provides plenty of bonding force to hold the heater core in place. Make sure to get the core centered, straight, and with the nozzles pointing in. If your lid is hinged, you will want to do a test fit before attaching the core to ensure that the nozzles clear the edges. If your lid is not hinged, it may be easier to attach it first. We ended up cutting the output off to make it fit better.
Step 5Attach the Bilge Pump
The ArcticAir unit just leaves their bilge pump just dangling from the hose, but we wanted it to be more secure. The pump has a twist-off base, so we twisted it off and Gorilla Glued it to the bottom of the cooler. Make sure that it is angled so that you can easily run a hose from the pump output to the heater core input. We attached the base directly to the bottom of the cooler, which works fine, but we probably should have put some spacers in to increase water flow underneath. Also, the picture just shows where it goes. We haven't attached that hose yet, so ignore it.
Step 6Attach the Lid (Optional)
If you used a cooler with a hinged lid, skip this step. Otherwise, read on.
By hinging the lid, it makes it easier to open for loading ice and letting air flow in during operation. It also prevents the lid from sliding off and dribbling water out of the heater core while driving. You can use whatever you want for a hinge-a rubber strip glued on, a couple of cabinet hinges, whatever. We used a piano-type hinge that we found in our stockpile of random stuff. It goes all the way across the back, and allows the lid to flip all the way back, but still close completely.
By hinging the lid, it makes it easier to open for loading ice and letting air flow in during operation. It also prevents the lid from sliding off and dribbling water out of the heater core while driving. You can use whatever you want for a hinge-a rubber strip glued on, a couple of cabinet hinges, whatever. We used a piano-type hinge that we found in our stockpile of random stuff. It goes all the way across the back, and allows the lid to flip all the way back, but still close completely.
Step 7Plumbing and Fan Guards
This is fairly straightforward. Connect a hose from the output of the bilge pump to the input of the heater core. In most cases, it doesn't matter which nozzle is used as the input. We just let the output dribble back in, but if the noise bothers you, you could attach a hose to the output. This would also be used as a drain hose.
We also attached a piece of bicycle inner tube rubber to catch water that drips from the output and that condensates on the core. It was cut to fit around the back edge and a couple inches up he sides, and secured with a mega-rubber band we found. This may be unnecessary if you attach a hose to the output, or if your heater core is configured differently.
This would also be a good time to attach wire fan guards to the fans. Just put some screws through the guards into the top holes.
We also attached a piece of bicycle inner tube rubber to catch water that drips from the output and that condensates on the core. It was cut to fit around the back edge and a couple inches up he sides, and secured with a mega-rubber band we found. This may be unnecessary if you attach a hose to the output, or if your heater core is configured differently.
This would also be a good time to attach wire fan guards to the fans. Just put some screws through the guards into the top holes.
Step 8Wiring
It would be difficult to make the make the wiring for a project easier than this. There should be a red and a black wire coming from each fan, the bilge pump, and the 12V plug. Use wire nuts to attach them all together, and make sure the pump and fans are going the right directions. The fans should be blowing out, and the pump should be pumping through the hose. After everything is moving correctly, you can solder the wires together, or put a switch in the power cord. We also used small zip ties to hold the wires together and to the fan.
Step 9Operation
Pretty easy, really. Dump in enough ice to fill the cooler about 3/4 of the way, pour in about a half-gallon of water (thats two liters for the smart people) so that the bilge pump can work, and plug it in! And flip the switch if you installed one. Make sure that you open the lid slightly for return airflow. We found that flipping the handle over to prop up the lid provides plenty of airflow without letting the ice get too warm.
If everything is hooked up right, the pump should be humming away, and the fans should be blowing. The water is chilled enough to cool the air within a few seconds. You can put this in your car with the dead A/C (note: this will cool pickups and small cars. Don't bother on your Ford Excursion), you can hook it up to a wall outlet through a 12V battery charger, or you can clip it onto a small 12V gel cell.
If everything is hooked up right, the pump should be humming away, and the fans should be blowing. The water is chilled enough to cool the air within a few seconds. You can put this in your car with the dead A/C (note: this will cool pickups and small cars. Don't bother on your Ford Excursion), you can hook it up to a wall outlet through a 12V battery charger, or you can clip it onto a small 12V gel cell.
Step 10Test 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.
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.
Notes.pdf151 KBStep 11Possible Modification and Other Notes
We have some ideas for further modification that we may or may not implement. For starters, we will probably connect a hose to the heater core output. This will eliminate the burbling, trickling sound that is hard on one's bladder, as well as make it easier to drain. The ArcticAir units have a valve inside that you turn to redirect the output to an external hose so that you can drain the cooler out the window onto the flight line without wrestling it through the door. Another option would be a drain plug on the bottom, which is already on many models of coolers. We also are considering a vent system, so that the lid could remain closed while still allowing air to circulate. The ArcticAir units have a louver vent on one side for this purpose. A third modification would be some way to redirect the airflow. ArcticAir units have adjustable flaps over the fans, which could work, or some have a duct hose assembly to redirect the airflow where it is needed. A fourth, and painfully obvious, step would be to enclose all the wiring inside the lid or in a project box to make it look neater. However, for the time being, the zip ties are plenty for us. Also, we may try using Blue Ice-type ice packs, so that it would be reusable and not waste water.
This being a Go Green contest, I should put in a spiel about why you would bother with this. The main purpose is to make it more comfortable to drive a zero-emissions electric truck in Kansas in August. This runs off any 12V power source that can shove out 3 amps, so it can be used in other areas that need cooled, such as a hot workshop. Also, the ice lasts for hours when it's not running, and you can leave it on while you run into the store. The only disadvantage is that you could say it wastes water in the form of ice, but you can empty it out on your garden or lawn. It uses only ice water for cooling, which is about as non-toxic and environmentally friendly as you can get, and it kept a hose, a cooler, and a heater core out of a landfill. In other words, it uses environmentally friendly power to run environmentally friendly coolant through recycled parts in a zero-emissions vehicle. Can you get greener than that? I mean, this is #008000 at its best! Just make sure to recycle batteries.
This being a Go Green contest, I should put in a spiel about why you would bother with this. The main purpose is to make it more comfortable to drive a zero-emissions electric truck in Kansas in August. This runs off any 12V power source that can shove out 3 amps, so it can be used in other areas that need cooled, such as a hot workshop. Also, the ice lasts for hours when it's not running, and you can leave it on while you run into the store. The only disadvantage is that you could say it wastes water in the form of ice, but you can empty it out on your garden or lawn. It uses only ice water for cooling, which is about as non-toxic and environmentally friendly as you can get, and it kept a hose, a cooler, and a heater core out of a landfill. In other words, it uses environmentally friendly power to run environmentally friendly coolant through recycled parts in a zero-emissions vehicle. Can you get greener than that? I mean, this is #008000 at its best! Just make sure to recycle batteries.
Step 12Tales from the Comments
9 April 2010: I'm adding this step to address some of the comment subjects of the comments...with 384 comments and counting, it's not nearly as easy to just read through them.
1) Dry ice has a lower specific heat capacity than water ice, so while it is colder, it won't last as long.
2) Dry ice sublimates to CO2, which, in a confined space, will at best impair judgment, and at worst cause loss of consciousness. Driving a car requires being alert. I highly discourage using dry ice.
Seems like a good idea, I know--add 12V and that little plate gets frosty cold. But you have to consider the net movement of heat. All that a peltier does is create a heat differential...a difference in temperature between the two sides. It does this by moving the heat from one side to the other. If you put a peltier inside the car, it won't cool anything down, because the same amount of heat that is removed to make one side cool is released on the other side right back into the car. The only way this could possibly work is if it was mounted so that the heat was released outside the car.
Using salt water or alcohol to lower the freezing point, so it will be colder...not really. The temperature is determined by how cold your freezer is. Oh, and salt water is corrosive and will OM NOM NOM your heater core.
Let's take this
Remember the energy flow. If you freeze the ice in your own freezer, all the heat that is pulled out of the ice, and then some, is released into your house from the coils in the back of the freezer. You could use this to cool that hot bedroom, but the house as a whole will be warmed.
Dry ice instead of water ice
First, a clarification: water ice isn't 32°F, it's whatever the temperature of the freezer is, anything below 32degF...just like how the steel on your car can be 10°F on a cold day, or 100°F on a hot day. Dry ice can be any temperature below -109°F. Since it is much colder, id would theoretically put out colder air. The two main problems with this idea are:1) Dry ice has a lower specific heat capacity than water ice, so while it is colder, it won't last as long.
2) Dry ice sublimates to CO2, which, in a confined space, will at best impair judgment, and at worst cause loss of consciousness. Driving a car requires being alert. I highly discourage using dry ice.
Peltier Junctions
Seems like a good idea, I know--add 12V and that little plate gets frosty cold. But you have to consider the net movement of heat. All that a peltier does is create a heat differential...a difference in temperature between the two sides. It does this by moving the heat from one side to the other. If you put a peltier inside the car, it won't cool anything down, because the same amount of heat that is removed to make one side cool is released on the other side right back into the car. The only way this could possibly work is if it was mounted so that the heat was released outside the car.Isn't this just a swamp cooler?
Uhhhhhhhhhh....NO. A swamp cooler works by blowing air over wet stuff (straw, wool, air, you name it), which evaporates the water. Since evaporation is an endothermic process (splash alcohol on your hand and feel how much it cools as it evaporates), the air is cooled down---BUT is also wet and full of all the water that just evaporated, making it only suitable for places that are hot and dry. This air conditioner is simple heat transfer--heat is transferred out of the air into the ice water. Since the ice water is cold, vapor in the air condenses on the coils, so it actually pulls water out...making it much more suitable for humid Kansas summers.
Ye salty sea dog!
Using salt water or alcohol to lower the freezing point, so it will be colder...not really. The temperature is determined by how cold your freezer is. Oh, and salt water is corrosive and will OM NOM NOM your heater core.Liquid Nitrogen
Er...for the same cost, you could buy a new car...which has air conditioning...and doesn't involve frostbite...Let's take this Outinside
Remember the energy flow. If you freeze the ice in your own freezer, all the heat that is pulled out of the ice, and then some, is released into your house from the coils in the back of the freezer. You could use this to cool that hot bedroom, but the house as a whole will be warmed.OH NOEZ T3H POLAR BEARS
Yeah, yeah, it takes energy to freeze water, yada yada yada. If you can't handle your freezer running a bit extra, then quit whining and roll down the window.Using the existing core
Yes, you can hook it up to run cold water through the original heater core so it blows through the original ducts. The whole point of this was to be portable, though. If you want a more permanent installation, have at it.
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