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07-26-2021, 12:44 PM
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#1
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Member
Join Date: Dec 2018
Location: Smithers, British Columbia
Trailer: 2010 Escape 19
Posts: 48
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12v Air conditioning?
Has anyone out there installed one of the 12v air conditioners now available? Such as this
Based on the posted power consumption, they are significantly more efficient than their 120v counterparts. https://www.dometic.com/en-us/profes...tx-2000-262673
Our 19 has AC, but we have never used it, as we never camp at sites with power. Between solar, DC-DC chargers, and lithium batteries getting cheaper, it seems like “off grid” air conditioning is becoming feasible. Not sure it’s a mod I would ever actually do, but it’s fun to dream., and I am curious if anyone else is doing it, or contemplating it.
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07-26-2021, 04:03 PM
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#3
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Senior Member
Join Date: Apr 2019
Location: Wickenburg, Arizona
Trailer: 2019 E19
Posts: 129
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The smaller of the two (I didn't dive into the larger) seems to require a 190 amphour battery as a minimum connection, and the electrical feed is to be protected by an 80 amp fuse, even though the unit draws "only" 19 amps. If the inrush current for the compressor is so high as to require an 80 amp fuse, then you will probably want #6 AWG wire (or larger) feeding the unit. Would you really want to tap directly off the battery bank, as shown in their wiring diagram? Not for me!
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07-26-2021, 04:39 PM
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#4
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Senior Member
Join Date: Mar 2018
Location: Tulsa, Oklahoma
Trailer: 2012 E19
Posts: 1,724
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Something doesn't add up with that 12V A/C. It says 19A in eco mode, but 12A x 12V = 228W, and the unit claims to be a 2000W model. I have to wonder how much cooling is actually taking place in eco mode?
__________________
Losing weight puts one at much greater risk of becoming thin.
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07-26-2021, 04:47 PM
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#5
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Senior Member
Join Date: Feb 2013
Location: Santa Rosa County, Florida
Trailer: 2014 Escape 21 Tow: 2024 Toyota Tundra
Posts: 3,096
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Last year at the Quartzsite rally there was a Happier Camper demo model with a 12V Dometic rooftop A/C. A rep claimed that a 100 Ah lithium battery / 100W (I think) solar panel combo could handle it. Hmm. I'd like to see more info on this.
__________________
Mike Lewis
She don't lie, she don't lie, she don't lie-- propane
Photos and travelogues here: mikelewisimages.com
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07-26-2021, 05:52 PM
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#6
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Senior Member
Join Date: Feb 2010
Location: Oswego, New York
Trailer: 2017 Escape 21C, 2018 Ford F150
Posts: 5,362
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Quote:
Originally Posted by Mike Lewis
Last year at the Quartzsite rally there was a Happier Camper demo model with a 12V Dometic rooftop A/C. A rep claimed that a 100 Ah lithium battery / 100W (I think) solar panel combo could handle it. Hmm. I'd like to see more info on this.
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I wonder if that was vaporware (pun not intended). I have not seen anything from Dometic or elsewhere other than n the discussion at the Q.
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07-26-2021, 05:57 PM
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#7
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Senior Member
Join Date: Jul 2020
Location: Dallas, Texas
Trailer: 2019 E19, 2014 F150 S-cab 5.0L
Posts: 259
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Quote:
Originally Posted by Mike G
Something doesn't add up with that 12V A/C. It says 19A in eco mode, but 12A x 12V = 228W, and the unit claims to be a 2000W model. I have to wonder how much cooling is actually taking place in eco mode?
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The 2000W model shows an operating range of 10 - 58 Amps in the owners manual. However even allowing for a higher nominal system voltage of say 12.75V @ 58A = 739W so something seems amiss if they're saying it has 2000 watts of cooling capacity.
I'm assuming the 10A end of the rating is for the fan operating by itself and that the 19A eco-mode is the rock bottom speed for fan and compressor. But I agree, its hard to see a lot of cooling going on at that level of power draw. It would've been better for them to have shown a BTU range or at least a BTU rating in eco-mode. Usually when you omit technical information like that there's a good reason for doing so.
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07-26-2021, 06:23 PM
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#8
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Senior Member
Join Date: Jul 2020
Location: Dallas, Texas
Trailer: 2019 E19, 2014 F150 S-cab 5.0L
Posts: 259
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CruiseNComfort also sells a 12VDC mini-split 8k system, but its pricey. Info Here.
Looks like 49A @ maximum output.
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07-26-2021, 07:09 PM
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#9
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Senior Member
Join Date: Jan 2019
Location: Johnson City, Texas
Trailer: 2019 19 ft.
Posts: 484
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Houghton is the one
Quote:
Originally Posted by richm
...they are said to be using the Houghton 3400.
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The 33 1/2" wide by 8 13/16" high by 44 3/16" long dimensions match exactly the RecPro 13.5K BTU Quiet AC Unit with Heat Pump, Remote, Non-Ducted.
73/gus
__________________
Mary & Gus
K5MCL & KR4K
2019 E19' (F1), Mercedes Sprinter 2500 or GLS580
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07-26-2021, 08:45 PM
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#10
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Senior Member
Join Date: Oct 2020
Location: Houston, Texas
Trailer: 2022 5.0TA
Posts: 111
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Quote:
Originally Posted by gklott
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That page says, "Energy Efficiency Rating (EER): 7.94" for the RecPro. This is the first ceiling mount all in one unit I've seen that specifies an efficiency rating. Thanks gus!
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07-26-2021, 09:49 PM
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#11
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Senior Member
Join Date: Mar 2016
Location: Burlington Twp., New Jersey
Trailer: 2010 Escape 19
Posts: 7,111
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Quote:
Originally Posted by DougG
Has anyone out there installed one of the 12v air conditioners now available? Such as this
Based on the posted power consumption, they are significantly more efficient than their 120v counterparts. https://www.dometic.com/en-us/profes...tx-2000-262673
Our 19 has AC, but we have never used it, as we never camp at sites with power. Between solar, DC-DC chargers, and lithium batteries getting cheaper, it seems like off grid air conditioning is becoming feasible. Not sure its a mod I would ever actually do, but its fun to dream., and I am curious if anyone else is doing it, or contemplating it.
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A few of us have or are in the process of powering efficient 120V mini-splits with inverter compressors with a large lithium battery or bank tied to an inverter. Personally I think this is the best bet right now for off-grid A/C.
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07-26-2021, 10:35 PM
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#12
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Member
Join Date: Dec 2018
Location: Smithers, British Columbia
Trailer: 2010 Escape 19
Posts: 48
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Quote:
Originally Posted by Mike G
Something doesn't add up with that 12V A/C. It says 19A in eco mode, but 12A x 12V = 228W, and the unit claims to be a 2000W model. I have to wonder how much cooling is actually taking place in eco mode?
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I am certainly not trying to promote this particular unit. It’s just the first one to pop up as an example when I did a google search.
But just for fun, let’s take a closer look at the numbers Dometic provides. I think a few folks here are confusing cooling output with power consumption. This units max cooling output is 2000w or 6800btu/hr (1 watt = 3.41 BTU/hr) because air conditioners/heat pumps, in simple terms, are just moving heat from inside to outside, or outside to inside. Rather than converting electrical energy into heat, an efficiency of greater than 100% is possible (and any half decent ac/heat pump does achieve better than 100% when the outside temp and inside temp are within 10 degrees Celsius of each other. For example, I have attached a screen shot for the dometic penguin II showing that, in the right conditions, it can extract more than twice as much heat energy as it consumes, and this isn’t a particularity efficient unit.
EER ratings also show this, as they are a ratio between power consumption in watts, and BTU/hr output. An EER of 3.41 would indicate a “100% efficiency”. As Richm pointed out above, EERs in the teens are possible indicating 5+ times the electrical input can be achieved.
Determining a defendable EER for a DC powered Air conditioner, I would imagine, is somewhat difficult, as depending on battery type, cable run, wire size, battery state of charge etc. The unit is likely to see anywhere between 10.5 and 14v. Also, I have no idea if the numbers posted on the dometic website are for the same conditions as required for an official EER. But as a quick and dirty exercise, using domestics numbers, (max BTU/hr = 6824, max current = 58 amps, and a nominal voltage of 12.5) we get an EER OF 9.41.
Assuming a linear efficiency (unlikely, but hey, this is a theoretical exercise) if 58 amps produces 6824 BTU/hr, then 19 amps would result in 2200BTU/hr. I figure my 19 has about 450 sq feet of surface area, and if we assume an r value of 2 (this is just a guess, I have the extra insulation) then the eco mode would achieve a 5 degree Celsius temperature reduction inside the trailer (running non stop), and reduce humidity some. Not earth shattering, but enough to make it comfortable a lot of the time. If you had say 300 amp-hours of lithium, 8 hours of run time in eco mode would be ~50% of your battery capacity.
Certainly it would seem that the mini split options are more efficient. But I like the idea of skipping the big inverter and mounting it in the same spot as the existing AC. That being said, I will admit the 4awg cable run would be a bit challenging to conceal nicely. Hmmm…..
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07-27-2021, 01:05 PM
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#13
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Senior Member
Join Date: Jan 2019
Location: Johnson City, Texas
Trailer: 2019 19 ft.
Posts: 484
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Nomadic Cooling
Quote:
Originally Posted by DougG
Has anyone out there installed one of the 12v air conditioners now available?
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We've seen several Sprinter Vans with 12VDC air conditioners from Nomadic Cooling. These get excellent reviews, but they are pricey and have long delivery times. They also require a large battery bank (≥ 600 AHr) and lots of solar (≥ 750 W).
The 9830 BTU unit (Model 2000) lists:
75 Amp Compressor
Eco Mode 30A-40A @ 85 Fehrenheit
Powerful Mode 55A Max Cool @ 85 Fahrenheit; 72A Max Cool @ 100 Fahrenheit
According to ABYC E-11 and RVIA LV, you would need at least 6 AWG 105C wire. We would use 4 AWG or 2 AWG to achieve the required ampacity with no bundling restrictions and to reduce voltage drop.
The 11830 BTU model 3000 has a 120A requirement for MAX cool.
These specifications seem reasonable for a 12 VDC air conditioner.
A big plus is that these Nomadic Cooling units list a noise level comparable with the Houghton Bellaire units.
73/gus
__________________
Mary & Gus
K5MCL & KR4K
2019 E19' (F1), Mercedes Sprinter 2500 or GLS580
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08-06-2021, 03:22 PM
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#14
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Senior Member
Join Date: Jan 2019
Location: Johnson City, Texas
Trailer: 2019 19 ft.
Posts: 484
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RecPro now offers 12 VDC AC
Received this RecPro link today for their new 12 VDC air conditioning. Marketing emphasis is on quiet and high efficiency. Highlights include:
- Compressor BTU rating: 20,000 BTU/hr
- Use 2 gauge wire for installation from the battery to the AC unit
- As a general rule of thumb, this unit should be able to cool the temperature of the air by 17-24 degrees
This RecPro unit has "Premiere" and the Premiere Product logo on the housing. It seems similar to the Premiere Products Turbo Air 2.
Suspect there will be more 12 VDC AC units hitting the market, given the VanLife movement, Class B motorhome sales increase, more solar on RV roofs, and larger LiFePO4 battery banks.
NomadicCooling is the 12 VDC AC that we often see on customized vans.
73/gus
__________________
Mary & Gus
K5MCL & KR4K
2019 E19' (F1), Mercedes Sprinter 2500 or GLS580
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08-06-2021, 05:51 PM
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#15
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Site Team
Join Date: Dec 2017
Location: Mid Left Coast, California
Trailer: 2014 Escape 21
Posts: 5,104
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i was stuck in my E21 for a day with the AC running full bore at max cool, in 106F muggy conditions the interior didn't get much below about 80F during peak heat. This is the standard rooftop 120VAC on my E21, I believe its a coleman unit, and the EMS said it was drawing like 15 amps continuously at 120V, or 1800 watts. my E21 has the double pane windows and double insulation plus underside foam.
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08-07-2021, 06:44 AM
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#16
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Senior Member
Join Date: Jun 2010
Location: Central, Pennsylvania
Trailer: Escape#5 2022 E19
Posts: 26,268
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I remember my first air conditioned apartment and complaining about the heat. I was told that that a/c was designed only for a 20 degree differential for comfort reasons...........
__________________
Jim
Sometime life gets in the way of living.......
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08-07-2021, 09:08 AM
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#17
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Senior Member
Join Date: May 2013
Location: ..., New Mexico
Trailer: 2013 Esc19/'14 Silvrado
Posts: 4,193
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Looks to me like dreaming of an ac unit that replaces what we got and works off a 100 watt lithium battery and a 190 watt solar panel is totally pie in the sky.
__________________
Myron
"A billion here, a billion there...add it all up and before you know it you're talking real money." Everett Dirkson
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08-07-2021, 12:55 PM
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#18
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Senior Member
Join Date: Jul 2020
Location: Tacoma, Washington
Trailer: 2020 Escape 21
Posts: 174
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Quote:
Originally Posted by John in Santa Cruz
i was stuck in my E21 for a day with the AC running full bore at max cool, in 106F muggy conditions the interior didn't get much below about 80F during peak heat. This is the standard rooftop 120VAC on my E21, I believe its a coleman unit, and the EMS said it was drawing like 15 amps continuously at 120V, or 1800 watts. my E21 has the double pane windows and double insulation plus underside foam.
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That pretty much matches the experience I had in my 21 in Moab two weeks ago in 102 degree temps--the trailer wasn't hazardously hot, but it was by no means comfortable until well after midnight.
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08-07-2021, 02:58 PM
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#19
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Senior Member
Join Date: Dec 2012
Location: Edmonton, Alberta
Trailer: 1979 Boler B1700
Posts: 14,935
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Quote:
Originally Posted by MyronL
Looks to me like dreaming of an ac unit that replaces what we got and works off a 100 watt lithium battery and a 190 watt solar panel is totally pie in the sky.
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Presumably that was supposed to be a 100 amp-hour battery... but yes, it's not reasonable.
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08-07-2021, 03:52 PM
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#20
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Senior Member
Join Date: Jan 2019
Location: Johnson City, Texas
Trailer: 2019 19 ft.
Posts: 484
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~1 kW per hour
Quote:
Originally Posted by MyronL
Looks to me like dreaming of an ac unit that replaces what we got and works off a 100 watt lithium battery and a 190 watt solar panel is totally pie in the sky.
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Pie in the sky is correct.
Rule of thumb: Figure ~ 1 kW for each hour with a reasonable size AC, like the NomadicCooling (DC) or the Houghton Belaire (AC). Actual energy use will vary depending on outside temp and your thermostat setting.
Many owners use a soft start AC unit and a Honda 2200 for air conditioning.
73/gus
__________________
Mary & Gus
K5MCL & KR4K
2019 E19' (F1), Mercedes Sprinter 2500 or GLS580
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