12v DC Air Conditioner

[mmanning]

From what I have seen, mini spits are the new coolest thing to use in a bus. (pun intended)  Has anyone tried a 12v DC mini spit in their build?

Here is an example unit: https://practicalpreppers.com/product/air-conditioner-only/

[richard5933]

Like I've said in other threads, there are more and more options for 12vdc compressors every day. Semi trucks are now using 12vdc compressors to keep the sleeper cabs cool. There are bus suppliers making systems to keep an entire passenger bus cool running from DC power. 

[windtrader]

If value buys are important for the busnut, then DC cooling, at least from the provided link, is not in the cards. Moet likely characterized as niche or specialty market at this point, meaning limited variety and higher prices.


The primary reasons for selecting a DC unit is to avoid having a DC-AC inverter or maybe saving some efficiency. Don't see other big benefit.


On the other hand, those who travel, especially to the third world, know how common mini splits are. There are millions of these out there so prices and variety are good. One of the critical and key benefits of them are high efficiency and ability to run on fumes if necessary due to lack of robust and plentiful electricity. The soft start allows these to get going where power off the grid is marginal at times.

[mmanning]

I like the idea of having cooling options without the need for an inverter.  I'm not sure I'll go this route, but one of my Dometic rooftop units is having issues with its age.  I've been researching options.

Searching for "Sleeper DC Air Conditioners" has really shown me a lot more options that are out there, thanks!

[silversport]

From what I have seen, mini spits are the new coolest thing to use in a bus. (pun intended)  Has anyone tried a 12v DC mini spit in their build?

Here is an example unit: https://practicalpreppers.com/product/air-conditioner-only/

This system is 48v and needs 1000w of solar, for me this is a no.

[mmanning]

This system is 48v and needs 1000w of solar, for me this is a no.

It doesn't have to be solar, it could just be batteries that get tipped off by shore power or a generator.  I'm not sure I'd want to go with a 48v system, but I have been seriously considering a 24v system. 

[Jim Blackwood]

One advantage of the 48v system is that the conductors only have to have twice the current carrying ability of a comparable sized AC unit rather than 4 or 8 times the capacity for 28 and 12v respectively. It seems to make sense for a mobile platform where your alternator can be sized to power it at 100% and also charge the batteries but for a rig that will spend very much time connected to a shore line it seems to lose a lot of appeal. And if you are struggling to get 2 Kw out of your solar cells a 1Kw 12K btu AC unit does not sound real enticing. I dunno, maybe if you had 4" of closed cell foam insulation on all 8 walls and no windows?

Jim

[luvrbus]

I saw DC units being installed at Peterbilt in Boise on new trucks they are supposed to run all night on 2 batteries (G-31 size wet cells) they really blow cold air .LOL the 117F heat made a buddy reinstall a new Coleman 15k which I help do his 13,000 btu mini split just wasn't up to the task,this morning over coffee he said he was going to Campers World and buy another 15k Coleman and remove the split, he likes cold air and cares less about the watts and amps usage.We are doing fine in 117 heat and sun just running 2 of our 3 roof tops in the day time and 1 and night   

[ccbmster]

My bus has all but one window still in and uninsulated at all.
Roof is just as it was built, no added insulation.
Walls have a bit of insulation behind cedar walls (not paneling but the kind of cedar that most use vertically as wainscoting.  I put my cedar on horizontally and it looks great).
One 12K mini split cooled it all with a fan blowing air towards the front, except when the temps got into the mid to high 80's and then the front would get warm.  So I just put in a second 12K unit with the air handler in the living room towards the front of the  bus.  Those two units can freeze you out no matter the outside temp, and you can just barely hear them run.  I hate noisy roof airs and love the energy savings so that I can run an AC all night off from my LifePo4 battery bank.

[luvrbus]

My bus has all but one window still in and uninsulated at all.
Roof is just as it was built, no added insulation.
Walls have a bit of insulation behind cedar walls (not paneling but the kind of cedar that most use vertically as wainscoting.  I put my cedar on horizontally and it looks great).
One 12K mini split cooled it all with a fan blowing air towards the front, except when the temps got into the mid to high 80's and then the front would get warm.  So I just put in a second 12K unit with the air handler in the living room towards the front of the  bus.  Those two units can freeze you out no matter the outside temp, and you can just barely hear them run.  I hate noisy roof airs and love the energy savings so that I can run an AC all night off from my LifePo4 battery bank.

Some people live where it gets HOT  I shot his bus with my gun in the sun at  4 pm the temp reading on his side was a 167F lol 80F is sweat shirt weather here 117F is hot,my ducted roof top are only 24 DBA on high and 21 DBA on low 

[richard5933]

There are other options besides the commercially available mini-splits and roof a/c units. The custom built split units that Custom Coach installed in our bus are essentially commercial refrigeration units. The bits that would normally be found in the basement of the business (the compressor and condensing unit) are in a bay. The bits that would be in the walk-in cooler (the evaporator) are in a cabinet upstairs with ducting to get the air to the living space. The two parts are connected with a line set. The condensing unit has a specially-made aluminum cabinet in the bay which pulls in air from the side and exhausts through the floor.

With the huge number of compressor options out there today, it seems that it would be pretty easy for one to custom build a unit to suit nearly any purpose using off-the-shelf parts.

[luvrbus]

There are other options besides the commercially available mini-splits and roof a/c units. The custom built split units that Custom Coach installed in our bus are essentially commercial refrigeration units. The bits that would normally be found in the basement of the business (the compressor and condensing unit) are in a bay. The bits that would be in the walk-in cooler (the evaporator) are in a cabinet upstairs with ducting to get the air to the living space. The two parts are connected with a line set. The condensing unit has a specially-made aluminum cabinet in the bay which pulls in air from the side and exhausts through the floor.

It should be easy a lot of our AC and refrigeration in the restaurant's and C store are built on site,the problem now the wholesalers like Johnstone and Grainer won't sell AC or refrigeration components to the public anymore but I bet a bus person could figure a way around it     

.

[ccbmster]

Some people live where it gets HOT  I shot his bus with my gun in the sun at  4 pm the temp reading on his side was a 167F lol 80F is sweat shirt weather here 117F is hot,my ducted roof top are only 24 DBA on high and 21 DBA on low

I have zero doubt that my rig will be comfortable anywhere at all......short of hell maybe LOL

[luvrbus]

I have zero doubt that my rig will be comfortable anywhere at all......short of hell maybe LOL

Last time I checked we were just 1 door down from hell,we just finished Jeff's other Coleman they are noise makers not ducted ,he is enjoying the cold air now. I am surprised in this heat they are only drawing 12 amp each 

[windtrader]

I think it would be quite a challenge to source, design and build a split system that matches efficiency of some you can buy. After considering the time and cost of DIY multiple prototypes for tuning and refinement make buying one that delivers published specs a whole lot less painful.