Mini Split Air Conditioner / Heat pump

Here's another possibility -- Arctic Breeze . No price.
Small inside unit.
You'll see the 'recommended' power source is 6 AGM (unspecified capacity) batteries. I have 4 12v 140AH batteries. Seem to me that with a heavy duty (ie, 2 gauge) alternator charge circuit and 500+ w solar, this would be able to keep a smallish size camper from getting hotter than (your favorite hot place) during a brisk 115 degree Arizona summer afternoon on the rim of the Grand Canyon.

As a lot of you probably know, Earthroamer campers are designed to use battery powered air conditioning (as they have no generators on board).

However:

1. Their interior coach volumes are considerably less than that of a lot of Class A/B/C motorhomes.

2. Their windows, floors, walls, and ceilings are extremely well insulated.

3. Their air conditioners can only be run 8-12 hours before their large battery banks need to be charged - via a lot of sun time and/or idling of their dual-alternator diesel main engines.

So non-generator, partially solar based air conditioning is possible ... but it takes a lot of things to be set up just right ... including a main engine that can be idled for long time periods of no sun ... and maybe a hefty bank account.

There is possibly one best way to have sustainable self-contained, anywhere/anytime sun or no sun, quiet, and non-engine-idling RV air conditioning: Install onboard a large battery bank in conjunction with a built-in high amp hour recovery rate propane fuel cell system.

I prefer to air condition an RV with a generator - believing that it's (or should be) easier and less expensive for RV manufacturers, or us owners, to come up with a quiet diesel or gas generator way to handle it.

6000 BTU, bedroom cooling to sleep
12v 28amps 340watts

that means 8hr of cooling uses almost 240ampHrs
approx 60% of a 4Gc in series-parallel

but 500w of solar would probably run it during the daytime
but you need to have more than that to recharge the power used during the night

still its only a little above 1/4 of the power the OP was talking about 10amps*120v 1200w

340w for 6000btu cooling, very efficient

(2) of those would be 12000btu and use less than 2/3 the power of a RV roof top unit

still quite a feat to do with only solar and batteries

you can get enough solar on the roof to run A/C part of the time during the day
its running day and night 24hrs that becomes a logistics problem of returning power to batteries while keeping the A/C running at the same time

Walkdog wrote:
I've come to the conclusion that nobody here knows anything about minisplit air conditioners vs the regular stand topside airconditioner that come stand with a RV.

I think you're mostly right -- no shortage of opinion anyway.
I was seriously looking at a 12v (or 48v -- they had both) mini-split actually made for big rigs years ago, but they were just too expensive.
There is one advertised on Ebay that's about the right size, but no clue about the quality.

I wish RV A/C was more efficient
But none of that changes the physics of solar and batteries, electrical creation
10 amps 120v is is 1200 Watts aka approx 100 amps of battery draw to the inverter, didn't make any difference what type of device is drawing that 1200w

The OP saw amps, and thought solar would run it
He didn't realize it's all about Watts amps times volts is Watts
He needs at least ten times the power he thought he needed

10 amp 120v =1200 Watts
100 amps 12v = 1200 Watts

pnichols wrote:

time2roll wrote:
They are inherently more efficient than RV air conditioners is the biggest difference.

Huh???

Please explain.

For example ... why would a split 13.5K RV A/C be more efficient than a single package (on the roof or otherwise) 13.5K RV A/C .... especially with regards to a single package on the roof RV A/C with interior ducts distributed shooting down from the ceiling throughout the coach area?

Kindof related .... we specifically went with a 4 ton single package heat pump for our stick house because efficiency losses were less and reliability was better than having an outside-the-house condenser section connected via leakable, rottable, and rodent edible hoses to the inside-the-house evaporator section.How does the heat even get outside? Largest window style unit I have seen is just 2 tons... 4 tons seems like a monster. Or is this a through-the-wall unit?

A split system seems to violate K.I.S.S. -> keeping it simple by having everything built and held together right inside the same metal enclosure with all interconnecting tubes made of metal and short in length.

Start by comparing SEER ratings.

Next ANY ducting through the sun heated ceiling cavity is losing monster heat.

Most ducting leaks like a sieve. Why does cold air blow out of my outlets? More heat loss.

Have you checked your plenum divider? Mine barely divided anything and allowed a lot of air to just circulate in the unit.

More compact design will tend to be lower efficiency and lower SEER rating. This can be observed with home units that have higher rating have a larger condenser.

Mini-split cooling unit is fully contained in the RV. Just a couple coolant tubes and some control wires to connect to the condenser outside. No 14" x 14" hole to cause more heat transfer issues.

DrewE wrote:
The mini splits generally use more modern motor and compressor designs, with variable speed compressors and fans. (I think these are multiphase induction motors with variable frequency drives, usually...but that's rather immaterial). I think a good part of their better efficiency comes from being able to modulate the amount of cooling, rather than being always full-on or full-off, which I suspect lets the condenser work more efficiently--a lower coolant flow means greater cooling in the condenser, and hence more cooling for the energy input. There's no inherent reason why a traditional RV air conditioner could not incorporate many of these features, but at present they do not do so.

What you say above is what I thought that the situation might be. As usual, many aspects of "modern" RV's still wind up being old technology.

FWIW, our stick house single package heat pump has a variable speed scroll compressor - which runs at 100% volumetric efficiency - and a variable speed air distribution fan, both of which in combination leads to reduced energy consumption. It's sound out the registers varies from whisper quiet to a rushing wind, all automatically controlled.

There's no reasons, beyond cheaping out, that RV heat pumps and air conditioners couldn't be made the same way .... thus MAYBE allowing an EU2000i Honda generator to power an RV's 13.5K heat pump at nearly all altitudes.

pnichols wrote:

time2roll wrote:
They are inherently more efficient than RV air conditioners is the biggest difference.

Huh???

Please explain.

For example ... why would a split 13.5K RV A/C be more efficient than a single package (on the roof or otherwise) 13.5K RV A/C .... especially with regards to a single package on the roof RV A/C with interior ducts distributed shooting down from the ceiling throughout the coach area?

The mini splits generally use more modern motor and compressor designs, with variable speed compressors and fans. (I think these are multiphase induction motors with variable frequency drives, usually...but that's rather immaterial). I think a good part of their better efficiency comes from being able to modulate the amount of cooling, rather than being always full-on or full-off, which I suspect lets the condenser work more efficiently--a lower coolant flow means greater cooling in the condenser, and hence more cooling for the energy input. There's no inherent reason why a traditional RV air conditioner could not incorporate many of these features, but at present they do not do so.

The fancy motors also mean that the startup current requirements are a good bit lower out of the box (i.e. without a separate soft start device). That's not an efficiency question, per se, but it is a very nice feature when running off a generator or inverter.

It also wouldn't hurt that you don't have a big hole in the ceiling with not much more than a sheet metal plate separating the evaporator and cold air from the hot outside air and motor and compressor and condenser.

RV air conditioners are among the least energy efficient ones available these days, I believe. Many window air conditioners do at least a little better. Probably most of the portable units with a hose going out a window would be even less efficient, I suspect, but that's about it.

time2roll wrote:
They are inherently more efficient than RV air conditioners is the biggest difference.

Huh???

Please explain.

For example ... why would a split 13.5K RV A/C be more efficient than a single package (on the roof or otherwise) 13.5K RV A/C .... especially with regards to a single package on the roof RV A/C with interior ducts distributed shooting down from the ceiling throughout the coach area?

Kindof related .... we specifically went with a 4 ton single package heat pump for our stick house because efficiency losses were less and reliability was better than having an outside-the-house condenser section connected via leakable, rottable, and rodent edible hoses to the inside-the-house evaporator section.

A split system seems to violate K.I.S.S. -> keeping it simple by having everything built and held together right inside the same metal enclosure with all interconnecting tubes made of metal and short in length.

Walkdog wrote:
I've come to the conclusion that nobody here knows anything about minisplit air conditioners vs the regular stand topside airconditioner that come stand with a RV.

What is to know?
They are inherently more efficient than RV air conditioners is the biggest difference.

As far as amp draw that will depend on load and heat. No one can give you an exact number. Takes a lot of energy to move the heat out of your poorly insulated RV sitting in the sun.

You can limit the cooling or add more solar panels and battery until it works for you in most conditions. I expect 1500 watts solar and 12,000 watt/hours battery would be about minimum. Is that even realistic for your RV?