Solar / Electric

[jimindenver]

It really bothers me there is no BTU listing, lots of claims but how much air does it move and can it cool an enclosed space the size of a person? Physics still apply, right? If you can not run a small 5,000 BTU air conditioner off of a good sized battery bank with 600 watts of solar for more than a few hours does it make sense even a greatly improved system that is portable and weighs much less could do as well or better? I can buy a lot of units that make claims of cooling but have yet to find one that works as well as the one that came with my RV. For that price I can buy a generator, air conditioner and a wagon to haul it all around knowing it will work! Some problems we have yet to find "good" solutions for, air conditioning is one of those. It looks to me you would need several with the big battery packs to come close to what most people consider "air conditioning".

Bump up the watts on the roof to 750-800 watts. That's my basic van design. In the summer months that is enough solar to run a energystar 5000 Btu window shaker during the peak of the day without the batteries knowing it. At least a good five hours. It will also replace the power needed to run it a few hours later in the day when the solar can not cover the load. 200 amp hours of usable batter capacity is ample power to cover a few hours of run time.

The problem comes when you need the solar to do both run the A/C during the day and replace the power needed to run it at night. Now you are talking a much bigger system and battery bank.  You might as well say systems because a Victron 100 amp charge controller can handle 1440 watts and while you can over panel to get to peak faster as well as hold it longer, you really need more. Twin 1000 watt systems are more in order because you know that the A/C isn't going to be your only load.

On the other hand, I can run the same A/C with my Sportsman 800 watt inverter generator that I got on sale for $152. I use it as the sun fades because I can suck 190 amp hours out of my bank nightly without bigger loads such as the A/C or water heater. It takes my 1185 watt solar system until noon just to replace that. Currently I do not have the battery capacity to add the A/C in. ( one 200 amp hour LifeBlue lithium)

 

[bullfrog]

^^^Thanks for the reality check, man that is a lot of power. Makes one appreciate that generator! It would be nice to see more efficient smaller air conditioning units but like Tesla's new panels and battery banks at what cost!

 

[ldsreliance]

The Christmas Nightmare.................."Battery NOT included"

If you already have your own batteries you might want to buy it without theirs.  It can be powered with any 24V DC power source with enough Amps.

Not sure about the 25 square foot in the shade thing.  I'll take your word for it, in theory, because I have no experience living in a van.  But no one knows for sure without testing it in the real world.  And that is what I try to do with my Youtube channel.

 

[highdesertranger]

Yeah the 25sqft thing is a red flag for me. As square feet means nothing when gauging how well an AC works. There is a huge difference between a 25sqft area that is 1 foot deep and one that is 20 feet deep. A more accurate description would be cubic feet but even then there are way to many outside factors, Ambient temp, sun load, insulation are just a few that I can think of. Highdesertranger

 

[Spaceman Spiff]

I know sq.ft. is stupid but that is the way residential air conditioning is specified.  There are a lot of assumptions and generalizations that go into that and most of those do not apply to a vehicle.  It is a lengthy but not difficult calculation to figure it out but it is unique for every application.

Vehicle air conditioners are (I think) about 2 Ton = 24,000 BTU or larger.  This, of course, is maximum.  At idle it is probably 1T or less.  Vehicle air is larger than house air because nobody lets their house get to 160º a car can get in the desert sun.

Sorry for the confusion (or have I confused you more?) 

 

[wayne49]

Giving the size in "Sq ft" means for a given residential area, with a standard height and required insulation in exterior walls and ceiling/roof.

So not applicable to vehicles and RVs, cheap or not so cheap.

 

[ldsreliance]

Giving the size in "Sq ft" means for a given residential area, with a standard height and required insulation in exterior walls and ceiling/roof.

So not applicable to vehicles and RVs, cheap or not so cheap.

That would be the assumption if the manufacturer provided that rating, but they don't.  At least not that I can find.  I am curious where Spiff came up with that number.

If a 5,000 BTU window air conditioner is rated for a room of 150 square feet in a house (with its associated insulation and cubic dimensions of ~8 foot ceiling) then that is approximately 1,200 cubic feet.  If we translate that to a van or RV, obviously we don't have anything close to the same insulation.  And Spiff's point is well made that if the van or RV is in direct sun it makes it much worse.  But lets assume it is in the shade so lets cut the number in half and say that a 5,000 BTU window unit is good for 600 cubic feet in a van or RV.

The ZeroBreeze Mk 2 is 2,300 BTU, which is 46% of the size of the above window unit.  So using the same ratings assumptions in a home, that would translate to 69 square feet (150 x .46) and 552 cubic feet (69 x 8).  Then if we cut the number in half for lack of insulation, we are left with 276 cubic feet.  For a sense of scale, a 2019 Chevy Express Cargo Van with standard wheelbase has a cargo volume of 240 cubic feet. 

Now we can debate my assumptions but it is close enough, in theory.  The ZeroBreeze Mk 2 should easily cool down a modest sized van or teardrop trailer or something.  But in the real world, who knows.

 

[jimindenver]

It’s a cool breeze blowing on you. It’s not going to cool down a hot van. Come to think of it a 5000 Btu A/c isn’t either without insulation. It takes two of them to even temper the heat in my 25 ft trailer.

When it gets hot down here the best I can do is turn on the A/Cs before it gets hot. That way there is a chance of keeping the temperature down inside. Once the inside gets hot the heat load is too much and the best the A/Cs are is a cool breeze.

I can take the pull the bedroom curtain and one of the A/Cs will handle a area the size of a queen sized mattress by 5 feet tall and keep it cool even in higher temperatures.

 

[Spaceman Spiff]

That would be the assumption if the manufacturer provided that rating, but they don't.  At least not that I can find.  I am curious where Spiff came up with that number . . .

The square foot info came from the Zero Breeze FAQ section.  Their specs don't tell much.

Sq.ft. is a simplified rating in common usage taken from the housing market that is easy for non-engineers to understand (like R-value).  If you want a better determination the SAE has all the equations you need to determine the actual cooling a ZB will provide for your vehicle in your location, tedious but not difficult.

Sorry I posted.

 

[bullfrog]

My 28' motorhome uses a 15000 BTU AC. It originally came with two 13,500 units. A 6,000 BTU window unit will not cool the entire motor home to 75 degrees in 100 degree temps but will cool a bedroom area 7' x 7' x7' , just my real world experiences. Spiff your thoughts are always appreciated, thanks again.

 

[jimindenver]

Twin 5000's can barely keep the 25 ft travel trailer around 80 degrees in 100 degree plus heat. Most homes are insulated much better than my trailer.