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Topic: 12 Volt Rooftop AC (Read 1084 times) previous topic - next topic

12 Volt Rooftop AC

I haven't finished watching this video yet but this could be a game changer...
https://youtu.be/4lvFKJIOG8I?si=VJgmur4ggkIWlqiM
1993 U225 Build #: 4285
500 Watts Solar
Honda CRV AWD
Former 1981 Foretravel Travco
Retired, Full Time Off Grid Snowbird

Re: 12 Volt Rooftop AC

Reply #1 –
And if you are interested in an evaporative (swamp) cooler that runs on 100 or less watts, check this out!
https://youtu.be/YZYke057Ahg
1993 U225 Build #: 4285
500 Watts Solar
Honda CRV AWD
Former 1981 Foretravel Travco
Retired, Full Time Off Grid Snowbird

Re: 12 Volt Rooftop AC

Reply #3 –
KOOL!
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: 12 Volt Rooftop AC

Reply #4 –
I am putting two 24 volt DC units in my new build
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: 12 Volt Rooftop AC

Reply #5 –
I think that this would beat installing a mini-split.  Very interesting.  Surprised he didn't go in the size of wire he ran.  I am guessing he ran #8 at minimum.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: 12 Volt Rooftop AC

Reply #6 –
Quote from: Dakota Slim –
And if you are interested in an evaporative (swamp) cooler that runs on 100 or less watts, check this out!

Do you know much about the psychrometrics? Swamp coolers (evaporation cooling) works in places like the desert with very low relative humidity. They will not make you comfortable anywhere there is a humid summer (east coast, midwest).
1998 U270 34'

Re: 12 Volt Rooftop AC

Reply #7 –
Quote from: John S –
I am putting two 24 volt DC units in my new build
What brand? A little more detail would be useful and helpful for the discussion.
1998 U270 34'

Re: 12 Volt Rooftop AC

Reply #8 –
Quote from: krush –
Do you know much about the psychrometrics? Swamp coolers (evaporation cooling) works in places like the desert with very low relative humidity. They will not make you comfortable anywhere there is a humid summer (east coast, midwest).
Hi krush. I'm a desert kind of guy who spends most of his time in AZ, SE CA and NV. Both the Hessaire and Vevor coolers I have used have excellent and efficient fans, and those work anywhere. Also, the Vevor has a tray for ice and comes with refreezable ice packs.
In the past when it got too hot I'd go north, head to a higher elevation or go to the cooler parts of Oregon.
I can always plug in somewhere or run the generator, but I'm thinking about adding more solar panels and lifePo4 battery storage along with one or 2 of these 12 volt DC units. 
1993 U225 Build #: 4285
500 Watts Solar
Honda CRV AWD
Former 1981 Foretravel Travco
Retired, Full Time Off Grid Snowbird

Re: 12 Volt Rooftop AC

Reply #9 –
Turbojack, I was interested in this video and was wondering what size wire he was using. Were you thinking # 8 was sufficient? Or do you think #6 would be needed?  I believe without looking at the actual specs on the a/c. 12 volt at 360 watts  would be 30 amps. On my  motorhome probably 30', the route he went from refrigerator vent to the house battery.
Tom
Tom and Michelle 2004 U270 36WTFS

Re: 12 Volt Rooftop AC

Reply #10 –
Quote from: Dakota Slim –
Hi krush. I'm a desert kind of guy who spends most of his time in AZ, SE CA and NV.

Then yes, a swamp cooler will work well there. But it will not work well in many other place.  Sit in 60F temps with 90% humidity--it is not comfortable.  For comfort, relative humidity matters as much (if not more) than temperature.
1998 U270 34'

Re: 12 Volt Rooftop AC

Reply #11 –
Quote from: T and M Long –
Turbojack, I was interested in this video and was wondering what size wire he was using. Were you thinking # 8 was sufficient? Or do you think #6 would be needed?  I believe without looking at the actual specs on the a/c. 12 volt at 360 watts  would be 30 amps. On my  motorhome probably 30', the route he went from refrigerator vent to the house battery.
Tom
I would say #8 at minimum. Since we are dealing with 12 volts, 2 motors, continues load, hot sun on roof where wire run is going to be,  I would run #6.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: 12 Volt Rooftop AC

Reply #12 –
#4 would get it under the 2% voltage drop
1999 36 ft U270
Build 5465

Re: 12 Volt Rooftop AC

Reply #13 –
Thanks for the answers. If I decide to install one in the future I will do my own research. But the info provided is useful!
Tom and Michelle 2004 U270 36WTFS

Re: 12 Volt Rooftop AC

Reply #14 –
The math is suspect for 385watt for 10000 BTU. IMHO.  I have a 12 V truck style on my van marked at about 550watts .  Draws the expected 60amps at full on.  The supplied cable wont power it ,even shortened.  It will run for a while on ECO mode  without catching fire .
  I would do a t least a 24 volt version .  That could work if you are happy running large cables into your roof.
  I moved all of my 3 185AH large LIiron batts from the bus to the van to run this thing. 
    Bus now has 3 amazon  100 AH batts. 
edit, watched the entire thing  . Pretty good .  I wonder if I could mount a solar controller on the roof and use short cables ?  Inside of a rooftop vent thingy.  That could work and this could run for a good while on 3-4 batts.

Re: 12 Volt Rooftop AC

Reply #15 –
Quote from: Protech Racing –
I wonder if I could mount a solar controller on the roof and use short cables ?  Inside of a rooftop vent thingy.  That could work and this could run for a good while on 3-4 batts.
One could probably put a battery bank on the roof as well...
1993 U225 Build #: 4285
500 Watts Solar
Honda CRV AWD
Former 1981 Foretravel Travco
Retired, Full Time Off Grid Snowbird

Re: 12 Volt Rooftop AC

Reply #16 –
Quote from: Dakota Slim –
One could probably put a battery bank on the roof as well...

I see your point about short run from battery bank to A/C unit.

But, putting all that on the roof would be dead last on my "how to do it" list. Lead acid are HEAVY, and Li are somewhat temperature sensitive.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: 12 Volt Rooftop AC

Reply #17 –
Quote from: wolfe10 –
I see your point about short run from battery bank to A/C unit.

But, putting all that on the roof would be dead last on my "how to do it" list. Lead acid are HEAVY, and Li are somewhat temperature sensitive.
Good point Brett.
AI Overview:
Your Useful Guide to Li-ion Battery Operating Temperatures:
LiFePO4 batteries typically operate within a temperature range of -20°C to 60°C (-4°F to 140°F), with optimal performance between 0°C and 45°C (32°F to 113°F). While the operational range is broad, maintaining the battery within its optimal temperature range extends its lifespan and ensures safety.
1993 U225 Build #: 4285
500 Watts Solar
Honda CRV AWD
Former 1981 Foretravel Travco
Retired, Full Time Off Grid Snowbird

Re: 12 Volt Rooftop AC

Reply #19 –
In reading there information they say to run #5 and if you can not get use #4 wire.  So there is our correct answer to wire size
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago