Air Conditioning When Vehicle is Off Possible?

[DHC6twinotter]

Hey all,

So, as I've been on my road trip, I've had a few hot night sleeping in the 4Runner. This got me thinking about a way to run the AC overnight.

I don't know if this would work, which is why I'm posting, but here's what I'm thinking:

Buy an electric AC compressor from a Prius or some other car that uses electric compressors. Mount it somewhere underneath. Keep all other existing 4Runner AC components and reroute the AC pressure lines to the electric AC compressor. Install 1 or 2 deep cycle batteries to run the compressor off of at night, and install an electric fan in front of the condenser.

I don't know the power draw of an electric compressor, so my main question is how long could an electric compressor run on a couple batteries? I know some Prius cars have solar panels on the roof to keep the AC going while the car is parked, so the power draw must not be too bad.

As an added benefit, the existing belt driven compressor could be modified to work as an air compressor. :D

Anyways, you all think this is possible? Dumb idea?

[Seanz0rz]

from what i see of the expo world, you might get a couple of hours out of those batteries, tops. you dont want to discharge them too much because you will end up ruining the battery (even a deep cycle).

id say look into a propane fired AC, but those do not exist apparently... just refrigerators.

i think the weight of the batteries and the complexity would make it cost prohibitive and unreliable.

the other option is evaporative cooling like we use out in the southwest. if the air is dry enough, drape a soaking wet towel over one open window, put a screen over another, and put a fan blowing from the wet towel. cheap and simple, but only works if it is dry. dew points above about 60 will make it uncomfortable.

handy chart: http://www.consumerenergycenter.org/home/heating_cooling/images/evap_chart3.gif

i do want to try this on our RTT sometime. i might build a rig for it.

[4x4mike]

Running an AC creates a large power draw. I think air flow is key like Sean said. Maybe sleep under the stars or make some screens for your windows. I use a piece of screen over my sunroof (held in place with magnets).

[L33T35T Tacoma]

I didn't read the whole thing... but...

http://www.instructables.com/id/Portable-12V-Air-Conditioner---Cheap-and-easy!/

[YotaFun]

Dan, That Prius A/C compressor can drain a Prius Hybrid Battery pretty quick (I would say an hour or so) so I can't imagine it would last too long on to deep cycle battery.

I like the Idea of utilizing the Sunroof, my idea would be something like this:
http://www.target.com/p/holmes-window-fan/-/A-11153980?ref=tgt_adv_XSG10001&AFID=Google_PLA_df&LNM=|11153980&CPNG=home%20improvement&ci_sku=11153980&ci_gpa=pla&ci_kw=

Sean is right its all about air flow. But what L33T35T just posted sounds like a cool Idea

[Seanz0rz]

i have tried the ice radiator thing. it requires ALOT of ice.

[Robinhood4x4]

Like everybody says, it requires too much power. Your best bet would be to get a small window or portable A/C and stay in a campground with hook ups. Or maybe get a small honda generator to power it all night.

[corax]

If it's dry heat, this should work for you and be relatively cheap (less than $50). A co-worker built one last week for Burning man and is running it off one of those portable jump boxes. He said last year he ducted the air under his sheet and it was almost too cool. During the day it's recharged by a solar battery tender. In fact, the water pump and fan will run right off the tiny solar panel - battery tender & pump available at Harbor Freight.

http://burningman.rengeekcentral.com/swampcooler.html
here's another one with ducting: http://robotfun.wordpress.com/2011/12/21/swampcooler/

http://robotfun.files.wordpress.com/2011/10/complete-swamp-cooler.jpg?w=195&h=300

[corax]

But yeah, I'll second that an electric driven compressor will suck most batteries faster than it would take to go to sleep. You could also install an RV roof fan for air flow like Ruined Adventures (http://www.expeditionportal.com/forum/threads/63486-quot-The-Border-Runner-quot-build-thread-87-4runner-built-for-epic-PanAm-journey) did . . .
http://farm8.staticflickr.com/7030/6746445923_dbda8c0573_z.jpg

. . . or a window model like this (cheap junkyard 12V radiator fan with an inline resistor to reduce current draw & a grill to keep your fingers intact?)
http://farm8.staticflickr.com/7031/6746505049_a5767de09b_z.jpg

[Obi..]

Dan, as always, my answers are blunt and straight forward. (*I gotta find the pic of Lil'Bro's setup with a partial tent off the back of his 2nd-Gen.) They make fold-out tents that strap with magnets to the back of the Runner. Depending on local issues (bear country) they work relatively well and let you have that fresh air feel. ~That said, we all went backyard camping this w/e because of the heat and it was the best night's sleep I got in ages. See about just a small tent instead? Lil'Bro just hacked up and sewed a $15 tent to work for them.

[DHC6twinotter]

Awesome, thanks for all the input guys! Looks like the AC option pulls more power than I thought. The cooler idea looks interesting, but I'd rather not be buying ice all the time. Still might be worth looking into. I'll have to try a fan, and I like the screen with magnet idea, although I'll have to use that on the side windows since I don't have a sunroof. The swamp cooler looks like a great idea as well, and I'll have to tackle that once I settle down somewhere.

Thankfully, I've managed to stay at places or altitudes where the temperatures weren't too high. The worse was back in Iowa and North Dakota, and things should start to be cooling off, although I do have a week or so in Utah yet.

I do have a tent with me as well, although I've only used it recently in Flagstaff.

Thanks again for the input!