12v Air conditioning?

[richm]

I think room on the roof could be a deciding factor for 12V AC. A 12V AC unit might work just fine with three 400A solar panels -- if there was room.

[LarryandLiz]

I’d wait a few more years to let other people work the bugs out

[Brian B-P]

Originally Posted by richm

I think room on the roof could be a deciding factor for 12V AC. A 12V AC unit might work just fine with three 400A solar panels -- if there was room.

I assume that was supposed to be 400 watt (not amp) solar panels. Three of them could produce 1200 W in total... at the equator, at noon, on a perfectly clear day.

In the real world they won't produce enough to keep up with a roughly 1 kW air conditioning load even at noon, let alone through other parts of the day. Maybe double that solar array, or expect only one or two hours of air conditioning for a day of battery charging?

[Doug2000]

Jarrod Tocci on YouTube reviewed this. Jarrod is Vanlife promoter.

Zero Breeze comes with its own Lithium battery and is portable, probably too small to cool a bigger Escape.

https://youtu.be/L8g6DvBU-IA


https://www.zerobreeze.com/products/...hoCEjQQAvD_BwE

[John in Santa Cruz]

Originally Posted by Doug2000

Jarrod Tocci on YouTube reviewed this. Jarrod is Vanlife promoter.

Zero Breeze comes with its own Lithium battery and is portable, probably too small to cool a bigger Escape.

https://youtu.be/L8g6DvBU-IA


https://www.zerobreeze.com/products/...hoCEjQQAvD_BwE

2300 BTU's is a joke. The Mach 8 in my E21 that could barely keep up with 106F exterior temps all day long (and well into the night) is 15000 BTU's, about 6X that cooling capacity

[richm]

Originally Posted by Brian B-P

I assume that was supposed to be 400 watt (not amp) solar panels. Three of them could produce 1200 W in total... at the equator, at noon, on a perfectly clear day.

Yes, that was supposed to be Watts, thanks.

Originally Posted by Brian B-P

In the real world they won't produce enough to keep up with a roughly 1 kW air conditioning load even at noon, let alone through other parts of the day. Maybe double that solar array, or expect only one or two hours of air conditioning for a day of battery charging?

Yea, that's a good point. So, how many hours of AC can you get from solar? One way to estimate this is Peak sun hours which converts a full day of sun into an equivalent number of hours at full illumination. Average peak sun hours varies with location and time of year.

Based on this, a typical example would be the equivalent of 5 hours of full illumination. Three 400W panels would provide 400W*3*5hrs= 6000 Watt hours. This would run a mini-split that consumes 600W for 10 hours. Granted, these panels and mini-split are at the extreme of what's available.

One interpretation of this is, AC on solar alone works best in limited locations with enough sun and in a time of year where hot temperatures are only a few hours. There are certainly places and times where that AC on solar work, but they are limited.

Even with these limitations, solar is appealing to me, because I would typically seek out good sun and mild weather anyway, where solar can sometimes be enough to enable extended boon-docking. I may still run a generator or pay for electric hook-ups otherwise, but I would value it for the extended boon-docking.

[richm]

Just noticed a facebook post by Johnny Hung on June 16 saying, "Thank goodness for battery and solar technology that we are now able to be self-sufficient in a small trailer such as our Escapes, all without the challenges of needing a gas generator." That includes running the AC full time.

[Brian B-P]

Originally Posted by richm

Just noticed a facebook post by Johnny Hung on June 16 saying, "Thank goodness for battery and solar technology that we are now able to be self-sufficient in a small trailer such as our Escapes, all without the challenges of needing a gas generator." That includes running the AC full time.

"Full time"? No. Enough hours per day to be comfortable? Maybe...

[gklott]

Originally Posted by richm

Just noticed a facebook post by Johnny Hung on June 16 saying, "Thank goodness for battery and solar technology that we are now able to be self-sufficient in a small trailer such as our Escapes, all without the challenges of needing a gas generator." That includes running the AC full time.

For example, a typical 1-ton (12,000 BTU/Hr) 120V mini split, EER 11 W/W cooling, averages ~ 1025 W for the compressor and ~ 50W for the fan. The manufacturer list 324-1488 W as power requirement range. This is similar to the unit Johhny Hung uses.

The Houghton Belaire rooftop 1.1-ton (13,500 BTU/Hr) 120V, EER 8 W/W cooling, lists 1550W for maximum cooling. This is the unit we use.

Bottom line: Figure about a 1-1.5 kWh for a typical 1-ton, 12,000 BTU/h, RV AC unit.

In our central Texas area, we get ~ 4.5 solar charging hrs equivalent per day. Johnny Hung gets about 6.5 solar charging hrs equivalent per day in his California area.

With our 340W ETI installed panels, we can add ~ 1500 Wh per day into our 6 Battleborn batteries (7.2 kW). Our two solar panels replace 1-1.5 hrs AC running hours. Duty cycle is the big variable. For a hot Texas summer day, temps in mid 90's, we have at least 2/3 to 3/4 duty cycle during the 3:00-6:00 peak consumption period.

Johnny Hung has about 9 Battleborn batteries equivalent storage and > 1700W solar panels, with sliding rooftop panels and his truck mounted panels. This is ~5 times ETI installed levels, which is possible because of no rooftop AC.

We converted our Honda EU2000i to propane, and we run it off our two 30-lb (7.1 gal) aluminum propane tanks. We get about 3 hrs/gal propane with full load on the generator.

There are always tradeoffs - such as generator noise. Thankfully, the Honda is relatively quiet.

Pick an approach, and go for it!

73/gus

[Centex]

Originally Posted by Brian B-P

"Full time"? No. Enough hours per day to be comfortable? Maybe...

Take care, Brian, he (Johnny Hung), with an E21 is running

• 10.2kW battery storage (DIY-built cell array); I don't recall his storage output voltage
• 1390 rated watts PV array on the trailer (max when parked, it's a slide-out array, some panels are covered when towing) + 350W rated on the tug corded to trailer = 1740 W rated max potential
• Multiple Victron solar controllers
• Claims a typical realized PVW factor for daily production of 6.5~7 (e.g. 11.5kW 'typical' measured daily output per system monitor/~1700kW rated array = 6.5 factor).
• 3kW Victron inverter
• residential inverter-type mini-split AC (120VAC) ~9kBTUH IIRC
• other misc electrical appliances including Cruise 195 12VDC compressor reefer

He acknowledges his use tends to boondock desert settings (good sun, hot days, cooler nights), mentions running AC when towing (with reduced PV array) to keep trailer interior temp consistent (and full-time air conditioning when in camp). Presumably by leaving home shore-power with the trailer pre-cooled and maintaining fairly constant interior temperature he avoids the (variable demand inverter-type) air conditioner ramp-up higher-current-hits when on battery/solar. That consistently-cool interior probably reduces reefer losses/loads, too.

Lotsa cubic dollars and talented effort in assembling in that rig but he strikes me as a credible guy in his description of components and use-experience anecdotes (Mr. Hung has nothing to sell, seems much less prone to hyperbole than Karl, IMO, YMMV).

BTW, I'm not on FB, got all the above from taking notes while watching and listening to the man on these:

Escape's Trailer Talk: Episode 4 | Tech Talk with Johnny Hung - YouTube

2021 Summer Solstice Virtual Rally Highlights - Escape Trailer - YouTube

Obviously none of this in the same league as a bolt-on rooftop 12VDC air conditioner with a few 12V lithium batteries of any ilk. Not for everyone but it's built by and for him

Oooops, Gus covered much of this while I was composing, Oh well ...

[richm]

Originally Posted by Brian B-P

"Full time"? No. Enough hours per day to be comfortable? Maybe...

His post says, "Since the weather has been warm the past months, my air conditioner is on full time and set at 72 degrees to maintain a constant cabin temperature."

[Brian B-P]

Originally Posted by richm

His post says, "Since the weather has been warm the past months, my air conditioner is on full time and set at 72 degrees to maintain a constant cabin temperature."

And that means that the air conditioner runs as much as required to maintain the set temperature. That could mean running 24 hours a day, but that's extremely unlikely; it could be only minutes per day.

Using the information extracted above, with 11.5 kWh available per day from an extreme solar system in ideal conditions, it is not possible to operate the air conditioning (actually running, not waiting to be needed) for 24 hours in a day. And it wouldn't be reasonable to expect that.

[Centex]

It would seem the clear and honest intent of Mr. Hung's description is that he turns the air conditioner system "On", sets a comfortable temperature, and the system maintains that temperature 24/7 without any intervention on his part (E.g. he never turns the air conditioner system switch "Off" to save battery power). Methinks that's what most folks mean and expect when they refer conversationally to 'full-time air-conditioning', and managing to have that without shore-power is the essence of the 'dream', isn't it?

If we look at the system input kW spec ranges for efficient inverter mini-splits with nominal ratings of ~9kBTUH we find examples varying between a minimum of 0.24kW or a bit less and a maximum of 1.4kW or a bit more or less. By pre-cooling on shore power before changing to battery-sourced power, and using the air conditioner on battery-power to maintain a relatively steady set-temperature through both the hot day and cooler night from the moment shore-power is abandoned, I suggest it's reasonable to expect the actual battery-sourced input to the air conditioner system will be consistently nearer the middle and lower part of that range rather than the higher. Yes, we gotta consider DC>AC inverter conversion efficiency, too.

Given the 'extreme' overall battery/solar system installed by Mr. Hung, and his use habits, I'd suggest that's not only possible but quite likely the situation he actually enjoys. Electrical and semantic technicalities notwithstanding (without getting wrapped up in what particular system component or switch is "On" or "Off", or, "running" or "waiting to be needed") that's the essence of the matter for most of us, isn't it?

I suggest it is quite reasonable to assume that Mr. Hung has actually achieved the 'functional goal of full-time air-conditioning on battery/solar power' in sense of what most of us understand that to be and some dream of enjoying. And that's pretty cool, IMO

[Brian B-P]

Originally Posted by Centex

It would seem the clear and honest intent of Mr. Hung's description is that he turns the air conditioner system "On", sets a comfortable temperature, and the system maintains that temperature 24/7 without any intervention on his part (E.g. he never turns the air conditioner system switch "Off" to save battery power). Methinks that's what most folks mean and expect when they refer conversationally to 'full-time air-conditioning', and managing to have that without shore-power is the essence of the 'dream', isn't it?

Yes. People just shouldn't expect even Johnny's mega-configuration to be able to run the air conditioner continuously. One really needs to look at total operating time per day to reasonably assess what is possible. In cool weather, any system is capable of keeping the air conditioner set all the time but never having to run.

[John in Santa Cruz]

Originally Posted by Brian B-P

Yes. People just shouldn't expect even Johnny's mega-configuration to be able to run the air conditioner continuously. One really needs to look at total operating time per day to reasonably assess what is possible. In cool weather, any system is capable of keeping the air conditioner set all the time but never having to run.

and in the 106F weather I was in 2 weeks ago, my Mach 8 (either 13500 or 15000 btu, I'm not sure which I have) was running 100% of the time for many hours from noon until way after sunset to keep the interior to the mid 80s. thats about 1500 watt*hours per hour. I was parked in the shade and my trailer has the 2014 extra insulation package with double pane windows, etc. all blinds were closed, the door curtain was closed, etc.

[alanmalk]

Originally Posted by John in Santa Cruz

and in the 106F weather I was in 2 weeks ago, my Mach 8 (either 13500 or 15000 btu, I'm not sure which I have) was running 100% of the time for many hours from noon until way after sunset to keep the interior to the mid 80s. thats about 1500 watt*hours per hour. I was parked in the shade and my trailer has the 2014 extra insulation package with double pane windows, etc. all blinds were closed, the door curtain was closed, etc.

In essentially the same conditions - Big Bend NP, Texas, late summer - running a Coleman Mach 8 13,500 BTU on low, we absolutely freeze. Either have to put on sweaters or wait outside for 30 minutes then return and shut off the A/C. It turns our '21 into a meat locker. So, I am wondering if there is a mechanical issue with yours that could be addressed by a service call? Just a thought...

[rubicon327]

Originally Posted by gklott

Received this RecPro link today for their new 12 VDC air conditioning. Marketing emphasis is on quiet and high efficiency.

Doesn’t seem very quiet on paper. 65 dB max indoor / 73 dB outdoor is pretty loud.

[John in Santa Cruz]

Originally Posted by gklott

Received this RecPro link today for their new 12 VDC air conditioning. Marketing emphasis is on quiet and high efficiency. Highlights include:...

k, i didn't check that link before.

Technical Data:

Power: 12V
Current: ~80 AMP
Maximum current: 100 Amp
Wattage: ~950-1100 depending on ambient temperature

(and elsewhere it says max 1200 watts)

wow, 80 to 100 amps. so a 4 x 100AH Battleborn lithium set will last *maybe* 4 hours before 100% discharged. you'll need 2000 watts of solar to keep up with that in the sort of summer climates where AC is needed 8-12+ hours/day.

oh, and 80-100A is way more than your typical RV power converter can output, so its no good if you're plugged in, even the big 36 foot sticky w/ slideout I was next to in Chico last month, he had a 55A power converter (I know, I replaced it for him on our last day there).

[Doug2000]

Originally Posted by John in Santa Cruz

2300 BTU's is a joke. The Mach 8 in my E21 that could barely keep up with 106F exterior temps all day long (and well into the night) is 15000 BTU's, about 6X that cooling capacity

Apples and Oranges.

The Zero Breeze that runs on battery isn't going to cool an Escape but would come in handy for someone boondocking. In the video I posted, an user put the duct under his sheets to cool off. Your not cooling an Escape with it. Your not cooling an Escape off of Lithium either without spending $10k. It's like comparing a Vermont Casting barbeque to JetBoil, each has their application.