I don't know much about ACs, so I apologize if this sounds like a silly question. But has anyone taken an electric powered air conditioning system designed for a car and put it into their RV? I was thinking you could run it off a backup alternator. Seems like a much cheaper option than ACs that are available for aviation. Not the best example I'm sure, but here's an example kit: https://www.amazon.com/Universal-electric-conditioner-conditioner%EF%BC%8CCamper-Conditioner/dp/B09NW58X27/ref=asc_df_B09NW58X27/?tag=hyprod-20&linkCode=df0&hvadid=563823049430&hvpos=&hvnetw=g&hvrand=9255227476358563632&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9067609&hvtargid=pla-1617615080874&psc=1
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automotive air conditioners
- Thread starter bmellis11
- Start date
Electric AC
Average current for an RV is 10-25 A depending on the type of flight.
The proposed AC has a starting current of 75 A and 40 A running.
Most alternators we use have a max current of 60 A.
Loading the alternator more than 80 % is not recomended other than in an emergency.
A belt driven compressor will be better choise.
Good luck
Average current for an RV is 10-25 A depending on the type of flight.
The proposed AC has a starting current of 75 A and 40 A running.
Most alternators we use have a max current of 60 A.
Loading the alternator more than 80 % is not recomended other than in an emergency.
A belt driven compressor will be better choise.
Good luck
jneves
Well Known Member
In addition to the current draw which already makes this a no go in my mind, even with a second alternator, you'd be adding 50 lbs to the empty weight at minimum.
Again, I'm a newbie at electrical so I still have research to do and this may be a silly question, but don't starters take more amps than the 75A it takes to start the AC? Seems like a 60A backup alternator could feed the 40A draw of the AC after it started.
Let's say belt driven is better, has anyone used a belt driven automotive AC in their RV?
Dad's RV-10
Well Known Member
There are several RV's flying with Airflow Systems air conditioning, which uses an engine (belt) driven compressor.
Do you know if a belt driven automotive AC compressor would work on an RV? Automotive AC systems cost about $700 to $2000 whereas the Airflow Systems AC system is around $9000. I can't imagine the technology is much different.
BillL
Well Known Member
But . . but . . .
"This electric air conditioner doesn't affect the horsepower of the car itself"
Now - that makes me feel better.
This is an interesting design worthy of consideration. But, before these (any) specifications could be used in design, it would be reasonable to test an actual unit to validate the claims. Also, who makes this compressor?
An advantage would be full cooling due to compressor speed at low engine speeds, but the current output of the alternator(s) would still have to be available.
Certainly an AC is an individual tradeoff, but 50 lbs is only for this unit, not ducting, controls, and a larger alternator to operate it up to cool air altitudes. Some people possibly just can not sit in a 120F cockpit for taxi, and TO.
Ben, watch this video, a NASA engineer helps make a water cooling module for a cool suit. He talks about how many BTU's it takes to cool a human body. You will find it interesting.
"This electric air conditioner doesn't affect the horsepower of the car itself"
Now - that makes me feel better.
This is an interesting design worthy of consideration. But, before these (any) specifications could be used in design, it would be reasonable to test an actual unit to validate the claims. Also, who makes this compressor?
An advantage would be full cooling due to compressor speed at low engine speeds, but the current output of the alternator(s) would still have to be available.
Certainly an AC is an individual tradeoff, but 50 lbs is only for this unit, not ducting, controls, and a larger alternator to operate it up to cool air altitudes. Some people possibly just can not sit in a 120F cockpit for taxi, and TO.
Ben, watch this video, a NASA engineer helps make a water cooling module for a cool suit. He talks about how many BTU's it takes to cool a human body. You will find it interesting.
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There's a lot more to an A/C installation than just the compressor. You have to find a place to put the condenser (radiator that dumps the heat out - have you seen the size of that in your car?), the evaporator (radiator that absorbs heat from the cabin), get sufficient airflow to both of those, without causing excessive drag, and you have to get the water generated in the evaporator out of the airplane without letting it pool somewhere to cause corrosion. And do all that without requiring the entire plane to be disassembled to service any of those parts.
There are a couple of electric driven A/C for airplanes, I saw one at Sun n Fun. It was about the same price as the engine driven compressor systems.
Generally they need about 75A on a 12v system (less on 24v), have less cooling ability than an engine driven compressor system, and you still have to deal with getting the hot air from the condenser and water out of the cabin.
There are a couple of electric driven A/C for airplanes, I saw one at Sun n Fun. It was about the same price as the engine driven compressor systems.
Generally they need about 75A on a 12v system (less on 24v), have less cooling ability than an engine driven compressor system, and you still have to deal with getting the hot air from the condenser and water out of the cabin.
Typical BS that particular on-line retailer allows. If this company is gonna defy physics, why waste it on a thermal cycle? Did I miss where they advertise a hovercraft on Amazon?
Mike D
Well Known Member
it can be done
There are several all electric AC's and several belt driven AC's available for aircraft. Many have them in their RV-10's.
For the aircraft specific AC's, the expense is mainly due to the small runs of production.
For the electric versions it comes down to efficiency of the compressor. There have been many improvements as electric cars become more common. The issue with taking one out of a electric car is getting it to run. It is typically not a straight 12v and have computer controls to run them. (and their not cheap either)
There are the big box portable units that could be run off a battery for a very short time. But this will be some weight and they are not efficient. you will have to port the hot air overboard. This is a dead end for me, but maybe someone else can see the way to make them work.
I have looked at small pet AC's. These are for dog houses and can run off of 12v and a small(ish) battery. I have gotten these to work in my RV-6, but wont cool down a RV-10. It might be some relief on a RV-4 if put in the rear seat
There is the ice chest version of a cooler. It is cheap to buy or make. But I'm in Houston so these ice chest coolers won't work for me. Adding humidity is not good here.
Another option is the cooling seat covers. there are a lot of fan versions but a few liquid cooled versions as well.
So, to give you some idea of what an electric AC uses, my electric car shows a 1kw increase to run the AC. if my math is correct, this is 100amps at 12volts. (I'm not electrically talented)
But, it can be done! It will take a lot of tinkering to get it to work. Sometimes you got to either put in the work or put in the money.
Experiment!
There are several all electric AC's and several belt driven AC's available for aircraft. Many have them in their RV-10's.
For the aircraft specific AC's, the expense is mainly due to the small runs of production.
For the electric versions it comes down to efficiency of the compressor. There have been many improvements as electric cars become more common. The issue with taking one out of a electric car is getting it to run. It is typically not a straight 12v and have computer controls to run them. (and their not cheap either)
There are the big box portable units that could be run off a battery for a very short time. But this will be some weight and they are not efficient. you will have to port the hot air overboard. This is a dead end for me, but maybe someone else can see the way to make them work.
I have looked at small pet AC's. These are for dog houses and can run off of 12v and a small(ish) battery. I have gotten these to work in my RV-6, but wont cool down a RV-10. It might be some relief on a RV-4 if put in the rear seat
There is the ice chest version of a cooler. It is cheap to buy or make. But I'm in Houston so these ice chest coolers won't work for me. Adding humidity is not good here.
Another option is the cooling seat covers. there are a lot of fan versions but a few liquid cooled versions as well.
So, to give you some idea of what an electric AC uses, my electric car shows a 1kw increase to run the AC. if my math is correct, this is 100amps at 12volts. (I'm not electrically talented)
But, it can be done! It will take a lot of tinkering to get it to work. Sometimes you got to either put in the work or put in the money.
Experiment!
Hangar 1271
Well Known Member
The ice chest AC units with a heat exchanger, like Arctic Air, actually remove humidity from the cockpit. Swamp coolers that just blow air over a cold water source do add humidity and don't work very well in humid conditions. I used one in FL for many years and it would drop the temperature of a Mooney from over 100 to a much more comfortable temp, say low 80s, in moments and lasted about an hour. plenty of time to taxi and climb to a more comfortable altitude and then on descent and land. Plus, you only pay for the weight when it is used and removed when not. I would use about 20 lbs of ice and a gallon of water making the whole thing about 40 lbs. Almost all FBOs will gladly give you the ice when you are ready to leave. Worked great. With a 6, 7, or 9 it fits nicely in the baggage area.
I have an 8 so my process was much more complicated but I made a unit and put the fan and exchanger in the cockpit. My biggest problem was the condensation off the exchanger, ergo the dehumidification, which is very significant.
AeroEngineer
Active Member
So the alternator makes power in some magical way that does not resist the turning of the engine?
Even Bart Simpson would be able to see through the BS in that claim
Actually a well designed unit will drop humidity levels just like an AC. The water / ice sits at bottom of chest. A pump moves the cold water to a heater core and the cabin air moves across the heater core. Works on the same principle at AC and will not add humidity, but remove it, as moisture in the air will condense on the heater core and liquid water drips to bottom of chest, just like an evap core on an AC system. The only difference from an actual AC system is that there is no pump and condensor to remove heat from the refrigerant therefore it only works until the water is no longer cool enough. It is also significantly less efficient than AC, as there is no multiplier that comes with latent heat of evaporation that you get with pressurized Freon moving to a low pressure state in the evaporator.
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So the alternator makes power in some magical way that does not resist the turning of the engine?
Even Bart Simpson would be able to see through the BS in that claim
To be fare to BillL, that was not his quote, he copied it from the description on Amazon.
Untainted123
Well Known Member
I built one from ideas I found on the internet, powered by Ryobi batteries (using a 3d printed adapter). I used an oil cooler for the evaporator, and separated the ice/fluid section from the top using insulated foam board. I procured a high flow fan and water pump to move the cold fluid through the oil cooler. It does dry the air (the water collects on the oil cooler, and then drip down into the ice area through a small drain hole in the foam board). I can get some pictures if anyone is interested in the design. The main feature is the separation of the ice/fluid from the cooling fins, it lasts a significantly longer time doing so.
Something that also helps: put the ice in the bottom, but the night before, mix water and RV anti-freeze (which I think is mostly ethanol and eco-friendly), and freeze that. It will stay liquid (which of course you need for the pump) cause of the anti-freeze, so you can pour a super cooled liquid onto your ice instead of room-temp or fridge temp water. Makes the ice last longer.
I found I don't really use it though, for several reasons: as mentioned, getting off the ground to cooler air is usually good enough, it takes up space in the baggage, I am more heat tolerant than most, and it requires prepping and loading into the plane, causing me to be hot and sweaty to begin with.
All told, I think I spent < $150, including the cooler, to put it together.
bjohnson1234
Well Known Member
Zero Breeze
I've been using the Zero Breeze Mark 2 and it works great. I vent it out through the baggage bulkhead and it cools my rv6 nicely. The best part is that it can run on its own battery power so no alternator concerns. They make a charging cable that can charge the batteries while it runs (it will still run out eventually with one battery if running continuously, but I generally only need it at low altitudes)
https://www.zerobreeze.com/products/zero-breeze-mark-2
I've been using the Zero Breeze Mark 2 and it works great. I vent it out through the baggage bulkhead and it cools my rv6 nicely. The best part is that it can run on its own battery power so no alternator concerns. They make a charging cable that can charge the batteries while it runs (it will still run out eventually with one battery if running continuously, but I generally only need it at low altitudes)
https://www.zerobreeze.com/products/zero-breeze-mark-2
Untainted123
Well Known Member
Zero Breeze
I hadn't seen these before, but it looks like a better alternative than putting in heavy duty alternator etc, and just be willing to have to charge it after use, or accept that you can't run it continuously. Looks like it uses outside air for cooling the condenser, which is good (otherwise you pull in uncooled/undried air to replace the air needed to cool the condenser, which is _way_ less efficient). Biggest benefit is you can remove it in the cooler months, or use it outside the plane after arrival (RV-15 camping? ).
If I was going to use one of these, I would go ahead and built in the ducting somehow to hook to it, that could be stowed or closed off when not needed, maybe scat tubing on the baggage wall or something. Wouldn't be much weight when not carrying the unit.
I hadn't seen these before, but it looks like a better alternative than putting in heavy duty alternator etc, and just be willing to have to charge it after use, or accept that you can't run it continuously. Looks like it uses outside air for cooling the condenser, which is good (otherwise you pull in uncooled/undried air to replace the air needed to cool the condenser, which is _way_ less efficient). Biggest benefit is you can remove it in the cooler months, or use it outside the plane after arrival (RV-15 camping?
).If I was going to use one of these, I would go ahead and built in the ducting somehow to hook to it, that could be stowed or closed off when not needed, maybe scat tubing on the baggage wall or something. Wouldn't be much weight when not carrying the unit.
bjohnson1234
Well Known Member
It comes with adapters to hook it up to ducting. I have a Y adapter to split it into two 2.5" vents that I run along the outside of the seats underneath the armrest area. The hose will hold its shape so you can run it forward and then point it back towards you if you want. In my rv6 with the unit behind the copilot seat that configuration took up the least amount of usable space in the baggage area.
https://www.amazon.com/gp/product/B08BRFSN3M/
https://www.amazon.com/dp/B09VXDWSN3
