Repurpose Auto AC for shipping container?

ToddT · 10-31-17, 03:25 PM

I'm building an office into half of a 40' high cube shipping container. I already have a couple of solar panels and a pair of 6v golf cart batteries. Being in Louisiana, air conditioning is a must. But, rather than run a small generator to drive a 5,000btu window unit, I've wondered about repurposing an AC out of a car.

I'm already planning on using a small engine to spin an alternator to maintain the batteries. Why not have a belt drive an AC compressor, too?

I understand car AC's put out between 25,000btu and 50,000btu. I'll already have other 12v devices in use.

Suggestions? Warnings?

jeff5may · 11-01-17, 08:15 AM

Use a gas engine from a riding mower to do your bidding. There are plenty of them on the second hand market with mower deck issues and other problems (like dingy paint and flat tire) to be had for next to nothing.

Most American vehicles use r134 as refrigerant and employ standard fittings for easy assembly. The newer vehicles use electric fans to move air through the heat exchangers and can run off of your alternator as a power source. Me likey pull a part. Fwiw, you can use condenser fan and heat exchanger assemblies on both sides of the system. Just remember to install a metering device to control the refrigerant flow.

ToddT · 11-01-17, 08:34 AM

Thanks... great points. I have a 13hp Honda that ran a pressure washer plus a 6.5hp or so clone that is hooked up to a dead 1000w generator. Both 4 strokes. Both horizontal shafts.

I've been into biomass gasification for almost a decade. Eventually, I want a gasifier running the engines. Next question: how to build a high compression Honda GX390 13hp engine? Optimizing an engine to run on woodgas calls for higher compression and advanced timing... the same as running on straight ethanol. It will be my off-grid and petroleum free office!

jeff5may · 11-01-17, 09:32 AM

Those Honda motors are hopped up mercilessly by the go kart racers, so lots of parts are available to mod them. Check out nrracing dot com and vegascarts dot com for some learning material. Those guys regularly run alcohol and nitromethane through their machines to get them to go fast.

ToddT · 11-01-17, 09:36 AM

Thanks. I'd done a bit of searching online for gokart racing but these sites will surely help. It's never a matter of "if" but "how hard?" and "how much?"

I've run my company off the grid for about eight years. I moved and have power in the main warehouse but really want to have a good portion of it running independently. It would be easier and likely cheaper to do it the standard route but what's the fun in that?

bpatton · 11-15-17, 01:10 PM

I have considered the idea as well but on a larger scale for a house with multiple compressors. My idea was that you could cycle the compressors as the loads change. The conclusion I finally came to was that its cheaper and simpler to run an inverter setup with a larger battery pack. While anything is possible, the efficiency of hermetic compressors is just too hard to beat. Plus the cost of solar now is so low, it might be worth it to just invest in the panels and build your own system out of window air conditioners or the like. Check out the Heat pump manifesto on this forum, it has great information on hacking your own AC sytems.
When I was looking into it the figure for around 5hp seemed the common most common need for nominal HP needed to run the compressor. If you do end up building this setup please post some pictures! I would love to see it.

10-31-17, 03:25 PM	#1
ToddT Lurking Renovator Join Date: Jan 2014 Location: Arkansas Posts: 9 Thanks: 9 Thanked 0 Times in 0 Posts	Repurpose Auto AC for shipping container? I'm building an office into half of a 40' high cube shipping container. I already have a couple of solar panels and a pair of 6v golf cart batteries. Being in Louisiana, air conditioning is a must. But, rather than run a small generator to drive a 5,000btu window unit, I've wondered about repurposing an AC out of a car. I'm already planning on using a small engine to spin an alternator to maintain the batteries. Why not have a belt drive an AC compressor, too? I understand car AC's put out between 25,000btu and 50,000btu. I'll already have other 12v devices in use. Suggestions? Warnings?

11-01-17, 08:15 AM	#2
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	Use a gas engine from a riding mower to do your bidding. There are plenty of them on the second hand market with mower deck issues and other problems (like dingy paint and flat tire) to be had for next to nothing. Most American vehicles use r134 as refrigerant and employ standard fittings for easy assembly. The newer vehicles use electric fans to move air through the heat exchangers and can run off of your alternator as a power source. Me likey pull a part. Fwiw, you can use condenser fan and heat exchanger assemblies on both sides of the system. Just remember to install a metering device to control the refrigerant flow.

11-01-17, 08:34 AM	#3
ToddT Lurking Renovator Join Date: Jan 2014 Location: Arkansas Posts: 9 Thanks: 9 Thanked 0 Times in 0 Posts	Thanks... great points. I have a 13hp Honda that ran a pressure washer plus a 6.5hp or so clone that is hooked up to a dead 1000w generator. Both 4 strokes. Both horizontal shafts. I've been into biomass gasification for almost a decade. Eventually, I want a gasifier running the engines. Next question: how to build a high compression Honda GX390 13hp engine? Optimizing an engine to run on woodgas calls for higher compression and advanced timing... the same as running on straight ethanol. It will be my off-grid and petroleum free office!

11-01-17, 09:32 AM	#4
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	Those Honda motors are hopped up mercilessly by the go kart racers, so lots of parts are available to mod them. Check out nrracing dot com and vegascarts dot com for some learning material. Those guys regularly run alcohol and nitromethane through their machines to get them to go fast.

11-01-17, 09:36 AM	#5
ToddT Lurking Renovator Join Date: Jan 2014 Location: Arkansas Posts: 9 Thanks: 9 Thanked 0 Times in 0 Posts	Thanks. I'd done a bit of searching online for gokart racing but these sites will surely help. It's never a matter of "if" but "how hard?" and "how much?" I've run my company off the grid for about eight years. I moved and have power in the main warehouse but really want to have a good portion of it running independently. It would be easier and likely cheaper to do it the standard route but what's the fun in that?

11-15-17, 01:10 PM	#6
bpatton Lurking Renovator Join Date: Oct 2017 Location: Tampa, Fl Posts: 10 Thanks: 2 Thanked 1 Time in 1 Post	I have considered the idea as well but on a larger scale for a house with multiple compressors. My idea was that you could cycle the compressors as the loads change. The conclusion I finally came to was that its cheaper and simpler to run an inverter setup with a larger battery pack. While anything is possible, the efficiency of hermetic compressors is just too hard to beat. Plus the cost of solar now is so low, it might be worth it to just invest in the panels and build your own system out of window air conditioners or the like. Check out the Heat pump manifesto on this forum, it has great information on hacking your own AC sytems. When I was looking into it the figure for around 5hp seemed the common most common need for nominal HP needed to run the compressor. If you do end up building this setup please post some pictures! I would love to see it.