12V air conditioner (evap or otherwise)???

mixedup · Veteran Member

12V air conditioner (evap or otherwise)???

Peter_n_Margaret · Guru

Get a couple of good quality 12V fans and open the windows.
Cheers,
Peter

Whenarewethere · Guru

Even if you use a 2.5kW Daikin or similar which are really efficient you would need to up your battery capacity & solar.

Evaporative works at its best the drier the air is, but you are always adding moisture to the air, which in turn adds to mould issues if it not a really dry environment.

As said above, fans & open windows. Passive things like windscreen sunscreens & awnings may be better, keeping the sun out & off surfaces.

Feet in a bucket of water, we've done that a couple of times & it is quite pleasant!

mixedup · Veteran Member

Thanks. Any idea what "dry" is re humidity level? Eg are evap coolers ok under say 90% humidity?

dabbler · Guru

Evap coolers should run as fan only and not depend on water unless fitted with a cutout sensor in the water tank. We use both a rechargeable fan and an evap. The fan pushes more air. An exhaust fan can create a decent cooling breeze too.

dabbler · Guru

The only 12v compressor type A/C systems are still belt driven by an automotive engine and 12v is for the fan and controls.

Whenarewethere · Guru

I don't know but I would think it is a sliding scale & it is relative to heat. In Sydney living next to the water we can have 23°C & the humidity is just horrible.

In Mildura a summer ago with 47°C we went swimming in the public pool, when we got out of the water & froze as the water was evaporating off us so quickly, then the dry heat hit us. Then back in the water again.

mixedup · Veteran Member

Thanks. Any idea what "dry" is re humidity level? Eg are evap coolers ok under say 90% humidity?

Whenarewethere · Guru

This is in fahrenheit. Looking at this graph you need to have no more than 50% relative humidity to have any worthwhile drop in temperature. But at the same time it will feel more humid.

Years ago in Alice Springs we were in a hotel with a swamp cooler. Yes it was cooler but it did feel more humid & I remember in the evening the cooling effect was pretty thin at best.

mastercool-evaporative-cooler-pads-tags-cooler-mastercool-evaporative-cooler-pads-tucson.jpg

Mike Harding · Guru

Think of an air conditioner is a heater in reverse:

You could not, sensibly, heat a caravan from a 12V system and the same applies to cooling - this is basic physics and the rule is "There is nowt for nowt".

To cool/heat a caravan requires 1kW to 3kW of energy depending on how cold/hot it is and how well the van is insulated (and other things). At 12V, 1kW requires 83A, this will be a major challenge for any, caravan practical, battery system.

As Peter said; buy a fan or two and in the cold put on a jumper, cut some wood and have a camp fire - or install a diesel heater.

Traway · Veteran Member

For the times when you cannot avoid the really high temperatures ie: 40s book in to a caravan park to use the mains power to run the air conditioner.

-- Edited by Traway on Monday 28th of October 2019 04:14:55 PM

BW · Senior Member

When I was in the N.T. working on a cattle station in the 80's , we were about 250 kms. from the coast . In the summer the heat used to make you sweat all night , no fans as the power was shut down at night . I made a evaporative cooler out of a 20 gallon drum with a couple of large squares cut out of the sides , covered the holes with potatoe bag , made of hession . Had a hose dripping on top of the hession and accumulating in the bottom , then draining onto the lawn . An old landcruiser 12 volt HJ fan drawing air from the middle , to my room . Run of a battery and charged during the day. Instead of the usual 40degs night and day , it was a comfortable Kmart 25 degs. By the way , in those days when kids were born out there , one of the first words kids learn't was K mart. Mt. Isa was a 2hr flight away .And K mart was usually a big stopping point , in those days. Still in the outback and still got an evaporative air con. running of a big set of batteries through a Big Arse Inverter. But it does run on a small 400watt if I want . There are good experts on here that will probably get around to you . I'm a sparky but I don't go into specifics . I just know what I need . I Have big stuff .

-- Edited by BW on Monday 28th of October 2019 05:41:07 PM

Whenarewethere · Guru

Using the Daikin 2.5kW (I have one in a property & a 5.0kW) The 2.5kW unit has a cooling capacity of 0.6kW min to 3.9kW max output.

At its rated output of 2.5kW it has an input of 0.42kW. So the AC is 595% efficient. On 12 volts it would chew up 35amps per hour plus the inefficiency of the inverter.

You can run the AC in economy mode so it will use less power but it will not be at the optimal efficiency. For arguments sake let's say 300%, so cool the caravan down at rated power for half an hour & then reduce the output of the AC. Good insulation etc will help reduce power consumption.

But it is still going to chew through battery capacity so you will need a pretty good set up. Maybe add another two 120AH batteries & some more solar.

A Daikin or similar is a lot more efficient than a standard caravan air conditioner, so it is a feasible system to run off batteries if set up properly.

rgren2 · Guru

Could try one of these.

www.google.com.au/shopping/product/18085778625832977721

Whenarewethere · Guru

Or a high efficiency custom build.

Peter_n_Margaret · Guru

rgren2 wrote:
Could try one of these.

www.google.com.au/shopping/product/18085778625832977721

OK outside. Bad news inside because everything will finish up wet and sticky.

Cheers,

Peter

Aus-Kiwi · Guru

Ac load is too high for DC to be efficient ? Or hell expensive Lithium batteries ? Dear I say a GOOD generator installed with sound deadening ? We just showered , went to bed with fans . Just getting to s l e e p in the first place !!!

Izabarack · Guru

I am currently trialling a Close Comfort and a bed tent. Claimed consumption is 300 Watts. I'm running it on a 700 Watt inverter. This is in a VW Transporter and I vent the unit discharge to the outside.

Iza

mixedup · Veteran Member

Izabarack wrote:
I am currently trialling a Close Comfort and a bed tent. Claimed consumption is 300 Watts. I'm running it on a 700 Watt inverter. This is in a VW Transporter and I vent the unit discharge to the outside.

Iza

Let us know has it goes Iza - does it have an warm air exhaust pipe you can put on? Is there a drain hose to drain out any water?

Izabarack · Guru

mixedup wrote:
does it have an warm air exhaust pipe you can put on? Is there a drain hose to drain out any water?

Been happy with it so far. You do have to remember it is not designed to cool the whole space in a room/van. My whinge about room air cons is that I rarely visit the more than about 30% of the space they are cooling. The unit is about twice the capacity of the Zero Breeze device some might have seen advertised. Does not come standard with a ducted exhaust like on most portable air con units but would be easy enough to construct one. There is a internal water collection tank and I have never had it more than half full after overnight use. The low power requirement also results in very low noise when running. The low noise is good for me because I get a bit of Tinnitus and the noise level and quality is in the white noise range.

Will be interesting come winter to turn the thing around and use it as a heater.

Iza

beaul · Veteran Member

Iza, how is that close comfort air con going, I am thinking of getting one.

BW · Senior Member

As beaul wrote:

Iza, how is that close comfort air con going, I am thinking of getting one.

__________________

Me to , 300 watts looks very doable with my off grid , when the evaporative cooler won't handle the humidity .

beaul · Veteran Member

Does anyone else have one of these (close comfort) what do you think, I like the power requirement and cooling for a tent.

beaul · Veteran Member

What brand of 700watt inverter and where did you buy it from.
I have had a lot of problems with inverters in the past