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Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: Dakota Slim on May 14, 2025, 04:41:44 pm

Title: 12 Volt Rooftop AC
Post by: Dakota Slim on May 14, 2025, 04:41:44 pm
I haven't finished watching this video yet but this could be a game changer...
https://youtu.be/4lvFKJIOG8I?si=VJgmur4ggkIWlqiM
Title: Re: 12 Volt Rooftop AC
Post by: Dakota Slim on May 14, 2025, 05:00:02 pm
And if you are interested in an evaporative (swamp) cooler that runs on 100 or less watts, check this out!
https://youtu.be/YZYke057Ahg
Title: Re: 12 Volt Rooftop AC
Post by: Hans&Marjet on May 14, 2025, 05:36:47 pm
I haven't finished watching this video yet but this could be a game changer...
https://youtu.be/4lvFKJIOG8I?si=VJgmur4ggkIWlqiM
Excellent...!
Title: Re: 12 Volt Rooftop AC
Post by: Chuck & Jeannie on May 14, 2025, 07:31:02 pm
KOOL!
Title: Re: 12 Volt Rooftop AC
Post by: John S on May 14, 2025, 07:36:13 pm
I am putting two 24 volt DC units in my new build
Title: Re: 12 Volt Rooftop AC
Post by: turbojack on May 14, 2025, 09:50:25 pm
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.
Title: Re: 12 Volt Rooftop AC
Post by: krush on May 15, 2025, 09:10:18 pm
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).
Title: Re: 12 Volt Rooftop AC
Post by: krush on May 15, 2025, 09:10:50 pm
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.
Title: Re: 12 Volt Rooftop AC
Post by: Dakota Slim on May 15, 2025, 10:03:52 pm
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. 
Title: Re: 12 Volt Rooftop AC
Post by: T and M Long on May 16, 2025, 09:34:38 am
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
Title: Re: 12 Volt Rooftop AC
Post by: krush on May 16, 2025, 10:24:06 am
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.
Title: Re: 12 Volt Rooftop AC
Post by: turbojack on May 16, 2025, 01:14:13 pm
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.
Title: Re: 12 Volt Rooftop AC
Post by: fatheeler on May 16, 2025, 05:42:16 pm
#4 would get it under the 2% voltage drop
Title: Re: 12 Volt Rooftop AC
Post by: T and M Long on May 16, 2025, 06:27:58 pm
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!
Title: Re: 12 Volt Rooftop AC
Post by: Protech Racing on May 17, 2025, 07:07:06 pm
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.
Title: Re: 12 Volt Rooftop AC
Post by: Dakota Slim on May 17, 2025, 08:47:45 pm
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...
Title: Re: 12 Volt Rooftop AC
Post by: wolfe10 on May 18, 2025, 08:05:38 am
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.
Title: Re: 12 Volt Rooftop AC
Post by: Dakota Slim on May 18, 2025, 10:13:30 am
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.
Title: Re: 12 Volt Rooftop AC
Post by: Dakota Slim on May 29, 2025, 08:37:57 pm
These AC units have some pretty impressive reviews...
12V RV Air Conditioner – 10,000 BTU Lowprofile Rooftop Air Conditioner (https://countrymodpro.com/products/12v-10000-btu-rv-air-conditioner-top-mounted-fast-cooling-system-for-rvs-trucks-vans-campers?variant=50549355151669)
Title: Re: 12 Volt Rooftop AC
Post by: turbojack on May 29, 2025, 10:38:54 pm
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