Mini Split Air Conditioner / Heat pump

I doubt you will get much more efficient than this 24 vdc mini-split, spec'd at 13k btu/hr drawing 816 watts. I don't believe it will reverse cycle though.
Looking at all of the DC air conditioners, ~850 watts for 13k btu/hr seems to be the standard. Note that most of these figures are effective watts- averaged over time- IOW, the unit draws 1300 watts but they factor in the duty cycle to come up with the lower number.

Heat pumps are way more efficient at power consumption per BTU of heat output than electric resistance based heaters.

HOWEVER, heat pumps still have a compressor - just like an air conditioner (usually a heat pump is an air conditioner "run in reverse" when you have the unit set to it's heating mode) - so when drycamping you still need the instantaneous high current spike capability to start it in heat pump mode as when starting it in air conditioning mode. What this means is - is you still need a fairly healthy power system when drycamping in order to heat or cool with a heat pump unit in an RV.

Personally, I see no reason to have a heat pump system in an RV except for electrical hookup campground use in which you are charged for your electricity consumption and in which cold temperatures aren't below around 35 degrees. In this situation heat pump heating would be less expensive than electrical resistance heater heating and maybe less expensive than propane furnace heating. I guess for more "flexibility" in choosing from a wide variety of camping situations that might present themselves - having an RV with a heat pump system along with a propane furnace instead of an air conditioning system with only a propane furnace - could be the smarter way to go.

Most of us have no experience, with a mini split cooling and heating

Which may be more efficient and produce more btu cooling for less energy use

But.. that does not change the circumstances of solar and battery Calculations

If it only uses 4 amps at 120v then power consumed and needed will be less than 14kwHrs

But you said '10 amps' and you said Texas summer

Please keep us informed of your progress

Wow, this was painful to read through. Bottom line, pay no attention to amps, by themselves, amp hours are meaningless. As has been pointed out, watts are what you need to pay attention to, as a watt is a measure of actual work- a watt is a watt, whether the voltage is 12, 24, 240, etc. An amp is different at all of these voltages.

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've come to the conclusion that you really want there to be a magic bullet and don't want to listen to those giving you good advice.

A 12k btu unit is going to run flat out most of the day in the summer texas heat because it's too small for most RV's bigger than 20-25'. That takes power regardless of the air/con style.

If the split units were that much better, you would see them quickly supplant the standard roof top units. Split units have been around a long time and that hasn't happened.

Walkdog wrote:
Honestly, I think most here no nothing of mini split air conditioners/heat pumps.

The unit you provided a link to is 240v-60hz drawing 4.05amps to produce 12k btu.

You are in texas so let's assume a 75% duty cycle: It's hot in texas so it will run a good part of the day and 12k btu is smaller than the typical 13.5/15k btu RV air/con units.

When running it will draw 972w or 17496w-h over a day. Assuming a 12v battery bank, you need 1458amp-hr of USABLE power. That translates to around 3000amp-hr with lead acid (assuming an agressive 50% of rated capacity) or about 1850amp-hr of lithium (assumes you can use 80% of the rated capacity).

Solar panels don't generate 24/7. Generally you can assume about 4 times the rated output per day, (ie: a 100w panel will put out about 400w-h per day). So to get 17496w-h, you will need just shy of 4400w of panels (this assumes you have ZERO other electrical loads). Assuming good panels putting out a generous 20w/sft, that's 220sft of panels needed. Assuming losses or hatches and other roof protuberances, you will need a 30' trailer with every available sft covered with panels.

The inverter to power this needs to be significantly larger than 972w as starting the compressor typically needs 2-3 times the continous draw, so figure on a 3000w inverter.

So let's total things up:
- Air/Con Unit: About a wash with a standard RV Unit.
- Custom installation of a split unit (as opposed to a couple hours to swap out a standard installation): Let's say $500.
- Sealing the existing Air/Con hole: Let's say $500.
- 1850amp-hr litium batteries: I just did a quick check and found a 60amp-hr (12v) for $300. So figure around $10,000 by the time you add in wiring, charge controllers, etc... (assuming you know what you are doing and don't have to farm it out to an expert).
- 4400w of solar panels: Assuming $1/w, that's another $4400.
- Solar panel installation: SWAG, $2000
- 3000w Inverter: $1500.

So grand total $18,900 for a solar powered air/con that totally dominates the RV and doesn't handle the other electrical loads...and in really hot weather may run out of power (12k btu isn't a lot in 110F weather).

By contrast, a $2000 generator will run the unit and assuming 4 gal per day at $4/gal 24/7 when camping and you camp 1 month per year, you have enough to cover 30yrs of fuel.

This ignores the fact that the batteries will eventually need to be replaced and work to keep the roof sealed will be substantially more expensive.
So yes, it can be done just not very practical.

Walkdog wrote:
https://www.homedepot.com/p/DuctlessAire-Energy-Star-12-000-BTU-1-Ton-Ductless-Mini-Split-Air-Conditioner-and-Heat-Pump-Variable-Speed-Inverter-220V-60Hz-DA1221-H2/300696598

4amp it says i assume that is a hour. Of course the one i'm acctually looking at is aroud 10-15. 10amp hours is 16 hour day is 160 amp hours in a 16 hour period. Right? Am i wrong. If so please put me back into place. So i should be able to run at least my air and pc and a 32 inch with direct tv attached and what not for a good while

NO, NO, NO!!!

4 amps is the instantaneous draw. To get Amp-Hr, you multiply by the number of hours that it's running, so if it's on 75% of the time, that's 72amp-hr at 240v. To convert to 12v (battery power), 1440amp-hr.

This is not meant to be mean but if you don't understand these basics, you need to take a class in the basics of electrical systems before building or having someone else build your system.

GordonThree wrote:
Look into an AC unit for a boat... Built with a Danfoss style compressor. Similar to the mini split but optimized to save power.

A 12k btu unit on our boat drew about 10amps at 120v.

Not much different from our RV 15k btu air/con.

Also marine units need a supply of cooling water. Unless you park your RV in the lake, not too practical.

Most (more than 1/2) of the math in previous comments looks reasonably good to me, but there is one issue nobody has mentioned.

If this unit CAN KEEP YOU COMFORTABLE during the heat of the day in direct sunlight, the nighttime load will be a small fraction of that.

The unit will be running at low speed and perhaps cycling on and off at night. So the four hours of battery operation predicted at maximum load in an earlier comment may stretch to 8 to 12 hours at the reduced nighttime load.

The permanent magnet variable speed compressors are the wave of the future, especially for boondockers, because they are very efficient and eliminate the big starting surge, allowing the use of smaller generators.

Walkdog,

Exactly what I said. You are on a voyage few folks have taken before. Please let us know how it works out.