12V "battery powered" air conditioners for off-the-grid usage are starting to hit the market. Manufacturers like Nomadic Cooling Co. and Dometic claim those 12V A/C units can be 70% more efficient than traditional 120V A/C rooftop units and are, therefore, suited for vanlife. In the following guide, we will compare 120V VS 12V air conditioning and define an electrical system that can support it and provide an acceptable autonomy. Keep cool and carry on!
Table Of Content
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1- 120V VS 12V Air Conditioner
1.1- What's The Difference?
120V or 12V, the cooling cycle of a heat pump (air conditioner or refrigerator) remains the same. The main difference on a 12V air conditioner is that it uses a highly-efficient compressor designed to work on 12V DC current. On a 120V air conditioner, the current coming from the battery bank must be converted from 12V DC to 120V AC and there is always an energy loss of about 10-15% associated with that conversion.
This might remind you of 12V vs 120V refrigerator (faroutride.com/fridge-guide)! In both cases, it’s the 12V compressor that makes it so efficient.
Nomadic Cooling Co. claims their 12V “battery powered” air conditioners are 70% more efficient than traditional 120V air conditioners. Unfortunately, we’re not in a position to verify this claim as it would require testing both 12V and 120V units on our van in real-world situations. So let’s take a look at the maximum current specification for both units:
Nomadic Cooling Co.
2000 | 9,830 BTU
max current at battery bank (12V)
Dometic Penguin II
11,000 BTU ("High-Efficiency" model)
max current at battery bank (12V)
That gap doesn’t prove that the Nomadic Cooling Co. is more efficient as the Dometic – being more powerful – might run less often (shorter duty cycle). However, it’s a good indication that the 12V unit is more suited for off-the-grid usage…
Nomadic Cooling Co.
2000 | 9,830 BTU
Dometic Penguin II
11,000 BTU ("High-Efficiency" model)
Well, that’s a massive price gap. So what can possibly justify the purchase of a 12V unit when it’s about 4x the price? See our decision tree below…
1.4- Decision (120V vs 12V)
12V Air Conditioner
120V Air Conditioner
If you really want off-the-grid air conditioning, 120V is just not an option. Don’t get us wrong: you can actually make a 120V A/C run from the battery bank, but you’ll have a few minutes/hours of autonomy at best (even going with, let’s say, 600Ah of Lithium batteries. That’s over $6,000 in batteries alone). Not convinced? Here is a question we got recently (and we get similar questions occasionally):
Hello. I have a Victron 3000w multiplus inverter/charger and a Dometic brisk 2 on the roof […], and after I connected the Victron it drained the batteries quickly with only brief use of the ac fan and a couple of minutes of actual ac. Do you have any feedback?
Our feedback is: there’s probably no issue at all with your setup, except that, unfortunately, you had the wrong expectations about air conditioning… The solution here is to use your AC on shore power only or to upgrade your electrical system (battery bank most notably) and your AC for a 12V unit. We’ll show how below.
2- Buying a 12V Air Conditioner
We’d personally go for the Nomadic Cooling Co. 2000 model because it’s easy to install (it fits a standard 14 x 14 Maxxfan fan cutout) and it’s easy to wire. (The Nomadic 3000 model is more powerful, but power consumption is quite high for off-the-grid usage):
UPDATE: Dometic recently released a 12V air conditioner, the Dometic RTX2000. You get less BTU than the Nomadic, however it draws less power and it’s also around $2K cheaper, so it’s definitely an option to consider…
Note that the recommended roof cutout dimension is 15.3in x 18.9in, which is larger than a standard roof fan cutout (14x14in). That being said, some people were able to make it works with a 14.5in x 14in cutout as shown in this video.2
3- Electrical System
3.1- Wiring Diagram & Items List
Download our “High-Power” wiring diagram (faroutride.com/wiring-diagram), use the addendum (image) below to wire the 12V air conditioner and make sure to use a 400A fuse with 4/0 AWG cable (“MAIN”) as annotated below:
A few clarifications:
- Use the dropdown menus and input all the wire length, in order to get all the correct wire gauge (e.g. youtu.be/9MEGls0qLZY)
- Because the air conditioner increases power demand on the electrical system, we’d recommend selecting a 2000W inverter/charger. It’s possible to go with a 3000W inverter/charger, but be aware that this might overload the system during peak power (e.g. when the inverter and the air conditioner are both running simultaneously at max power).
- NOMADIC 2000: The 12V air conditioner is connected to the bus bars via a 100A breaker. The correct wire gauge varies with the length and can be determined with this calculator: WIRE GAUGE CALCULATOR. Or simply put, 1 AWG gauge will work for any length under 30 feet total (15 feet red + 15 feet black).
- Dometic RTX2000: The 12V air conditioner is connected to the bus bars via a 80A breaker. 24ft of electrical harness is included with the RTX2000.
12V Air Conditioner
|#||Item||Description||Quantity||View on Amazon|
|1||12V Air Conditioner||Nomadic Cooling Co (2000 | 9,830 BTU)||1||View|
|2||100A Breaker/Switch, Surface Mount||Blue Sea 285-Series||1||View|
|3||1 AWG Cable 15 feet Red + 15 feet Black||Connect to breaker and bus bar||1||View|
|4||Lugs, 1 AWG Cable, 1/4″ Ring||Connect to breaker (Pack of 2)||1||View|
|5||Lugs, 1 AWG Cable, 3/8″ Ring||Connect to bus bar (Pack of 2)||1||View|
|1||Class T Fuse, 400A||Blue Sea (Catastrophic Fail Safe)||1||View|
|2||Class T Fuse Block||Blue Sea (Holds the Class T Fuse)||1||View|
|3||System Switch||Blue Sea (Main System Switch)||1||View|
|4||Bus Bar (600A, 4 studs)||Blue Sea||2||View|
|5||Cover for Bus Bar (for 600A 4 studs)||Protect the Bus Bar||2||View|
|6||40A Breaker/Switch, Surface Mount||Between Fuse Block and Bus Bar||1||View|
|7||Fuse Block (12 circuits)||Blue Sea (12V Distribution Panel)||1||View|
|8||Fuses Kit||Assorted Fuses (2A 3A 5A 7.5A 10A 15A 20A 25A 30A 35A)||1||View|
|9||Battery Monitor||Victron BMV-712 with BlueTooth||1||View|
|10||Cable, 4/0 AWG, 5 ft Red||Between battery and Bus Bar||1||View|
|11||Cable, 4/0 AWG, 15 ft Black||Between battery and Bus Bar + Ground||1||View|
|13||Lugs, 4/0 AWG Cable, 5/16″ Ring||Connect to Bus Bar, Terminal Fuse Block and Battery (Pack of 2)||1||View|
|12||Lugs, 4/0 AWG Cable, 3/8″ Ring||Connect to System Switch and Shunt (Pack of 10)||1||View|
|14||Cable, 8 AWG, 5 ft Black + 5 ft Red||Between Bus Bar and Fuse Block||1||View|
|15||Heat Shrink Terminal Ring, 8 AWG Cable, #10 Ring||Connect to Fuse Block (Pack of 3)||1||View|
|16||Heat Shrink Terminal Ring, 8 AWG Cable, 1/4″ Ring||Connect to Breaker (Pack of 3)||1||View|
|17||Heat Shrink Terminal Ring, 8 AWG Cable, 3/8″ Ring||Connect to Bus Bar (Pack of 3)||1||View|
|1||350W Solar||NewPowa 175W Mono Panel||2||View|
|2||Extension Cables, 8 AWG, 15 ft Red + 15 ft Black||With MC4 Connectors||1||View|
|3||Double Cable Entry Gland||For 8 AWG or 10 AWG Cable||1||View|
|4||40A Breaker/Switch, Surface Mount||Between Panels and MPPT Charger||1||View|
|5||MPPT Solar Charger||Victron 100|30 SmartSolar MPPT||1||View|
|6||40A Breaker/Switch, Surface Mount||Between MPPT Charger & Battery||1||View|
|8||Heat Shrink Terminal Ring, 8 AWG Cable, 1/4″ Ring||Connect to Breakers (Pack of 3)||2||View|
|7||Heat Shrink Terminal Ring, 8 AWG Cable, 3/8″ Ring||Connect to Bus Bar (Pack of 3)||1||View|
|1||60A Battery-to-Battery Charger (B2B)||Sterling Power BB1260||1||View|
|2||100A Breaker/Switch, Surface Mount||Blue Sea 285-Series||2||View|
|3||Cable, 4 AWG, 15ft Red||WindyNation||1||View|
|4||Cable, 4 AWG, 5 ft Black||WindyNation||1||View|
|6||Lugs, 4 AWG Cable, 1/4″ Ring||Connect to Breakers (Pack of 10)||1||View|
|5||Lugs, 4 AWG Cable, 3/8″ Ring||Connect to Bus Bar (Pack of 2)||1||View|
|1||2000W Inverter/Charger||Victron Multiplus 12|2000|120||1||View|
|2||Remote Control for Inverter||Victron Digital Multi Control 200/200A GX||1||View|
|3||Class T Fuse, 300A||Blue Sea (To protect inverter’s cable)||1||View|
|4||Class T Fuse Block||Blue Sea (Holds the Class T Fuse)||1||View|
|5||Cable, 2/0 AWG, 5 ft Black + 5 ft Red||Between Inverter/Charger & Bus Bars||View|
|6||Lugs, 2/0 AWG Cable, 5/16″ Ring||Connect to Inverter/Charger (Pack of 5)||1||View|
|7||Lugs, 2/0 AWG Cable, 3/8″ Ring||Connect to Bus Bar (Pack of 5)||1||View|
|8||30A Shore Inlet||Furrion 30A Marine Power Smart Inlet||1||View|
|9||30A AC Main||Breaker Between Power Inlet and Inverter/Charger||1||View|
|11||10/3 AWG Triplex AC Marine Wire||Between power inlet & inverter/charger||1||View|
|12||Lugs, 10 AWG Cable, #8||Connect to AC Main (Pack of 3)||1||View|
|13||Lugs, 10 AWG Cable, #10||Connect to AC Main (Pack of 3)||2||View|
|14||120V AC Distribution Panel (4 Positions*)||Blue Sea Panel: AC Main + 4 Positions*||1||View|
|15||6/3 AWG Triplex AC Marine Wire||Between inverter/charger & AC distribution panel||1||View|
|16||Lugs, 6 AWG Cable, #10||Connect to distribution panel (Pack of 10)||1||View|
|17||120V AC Wall Outlet||GFCI, 20A||1||View|
|18||14/3 AWG Triplex AC Marine Wire||To wire load that requires 15A or 10A breaker||1||View|
|19||Lugs, 14 AWG Cable, #8||Connect to distribution panel (Pack of 3)||1||View|
|20||Lugs, 14 AWG Cable, #10||Connect to distribution panel (Pack of 3)||1||View|
|1||50A Breaker (Double-Pole)||To upgrade 120V AC distribution panel to 50A instead of 30A||View|
|2||20A Breaker||For load that requires 20A breaker (e.g. A/C)||View|
|3||10A Breaker||For load that requires 10A breaker||View|
|4||120V AC Distribution Panel (6 Positions*)||*6 Positions panel is sometimes cheaper, check it!||View|
|5||12/3 AWG Triplex AC Marine Wire||To wire load that requires 20A breaker (e.g. A/C)||View|
|6||Lugs, 12 AWG Cable, #8||Connect to AC Main (Pack of 3)||1||View|
|7||Lugs, 12 AWG Cable, #10||Connect to AC Main (Pack of 3)||1||View|
|1||8 AWG Black/Red Duplex Cable (8/2), Ancor Marine Grade||100 feet||1||View|
|2||10 AWG Black/Red Duplex Cable (10/2), Ancor Marine Grade||100 feet||1||View|
|3||12 AWG Black/Red Duplex Cable (12/2), Ancor Marine Grade||100 feet||1||View|
|4||14 AWG Black/Red Duplex Cable (14/2), Ancor Marine Grade||100 feet||1||View|
|5||16 AWG Black/Red Duplex Cable (16/2), Ancor Marine Grade||100 feet||1||View|
|6||Heat Shrink Terminal Ring, 8 AWG Cable, #10 Ring||To connect to Fuse Block (25 Pack)||1||View|
|7||Heat Shrink Terminal Ring, 10-12 AWG Cable, #8 Ring||To connect to Fuse Block (25 Pack)||1||View|
|8||Heat Shrink Terminal Ring, 14-16 AWG Cable, #8 Ring||To connect to Fuse Block (25 Pack)||1||View|
|9||Heat Shrink Butt Connector, Ancor Marine||To connect to Loads (75 Pack Kit)||1||View|
|10||Heat Shrink Disconnect, 10-12 AWG Cable, 1/4″ Tab, Female|
To connect to certain loads (i.e. 12V Sockets) , to make “removable” connections (i.e. Fridge, LEDs) and to connect cable of different gauge together (i.e. LED Dimmer) (25 Pack)
|11||Heat Shrink Disconnect, 10-12 AWG Cable, 1/4″ Tab, Male||1||View|
|12||Heat Shrink Disconnect, 14-16 AWG Cable, 1/4″ Tab, Female||1||View|
|13||Heat Shrink Disconnect, 14-16 AWG Cable, 1/4″ Tab, Male||1||View|
|14||Heat Shrink Disconnect, 18-22 AWG Cable, 1/4″ Tab, Male||1||View|
|15||3M Scotchlok Quick Splice with Gel (14 AWG stranded)||We used that to parallel our LED lights (25 Pack)||1||View|
|16||Heat Shrink Tubing Kit (with adhesive)||To protect lug after crimping||1||View|
|17||Split Loom Tubing, 3/8″ diameter 25 feet||To protect wire bundles||1||View|
|18||Split Loom Tubing, 1/2″ diameter 25 feet||To protect wire bundles||1||View|
|19||Split Loom Tubing, 3/4″ diameter 10 feet||To protect wire bundles||1||View|
|20||Nylon Cable Clamps Kit||To secure cable/split-loom to wood||1||View|
|21||Zip Tie Mount with Adhesive||To secure cable/split-loom to metal||1||View|
|22||Nylon Zip Ties Kit||To secure cable/split-loom||1||View|
|23||Rubber Grommet Kit||To protect wire from sharp edge (going through metal hole)||1||View|
3.2- Customize Your Own Wiring Diagram & Items List
You can use our Van Electrical Calculator (faroutride.com/calc) to customize your own system. We’d recommend sticking with a 2000W inverter/charger (you can force the calculator to do so by switching to “manual” mode). For the Nomadic Air Conditioner, use 25Ah current (that’s the average current draw, per manufacturer claim) and something like 8 hours for daily usage. For example:
Image extracted from faroutride.com/calc
In the calculator, scroll down to retrieve your entire items list. Make sure to download the High-Power version of our wiring diagram (and use the addendum of the section 3.1 above the connect the air conditioner).
3.3- Managing Expectations
We have to accept how energy-hungry air conditioning is… To make it work off-the-grid, we need to invest in highly-efficient 12V air conditioner but ALSO on a large battery bank. That’s quite a financial commitment.
But yeah, it can be done.
That doesn’t mean you’ll be able to maintain the interior of your van at 68F 24/7 when it’s 95F outside though…
Reasonable expectations, for example, would be more like using the A/C to lower the temperature/humidity just a few degrees as it can makes the difference between a good night of sleep VS no sleep.
And keep in mind the calculations above do NOT include induction cooking, which is another energy-hungry appliance. “All-electric” builds are very appealing, but keep it real!
Bottom word: manage your expectations and remember that HOW YOU USE IT will have a tremendous impact on your autonomy.
3.4- Variables affecting Energy Consumption
A cooling machine (such as a fridge or an air conditioner) does not constantly work. It cycles between ON and OFF to regulate the temperature. This is called the DUTY CYCLE:
Duty Cycle (%) = (ON duration / Total duration) x 100
For example, if the air conditioner is ON for 1 minute then OFF for 3 minutes, the duty cycle is 25% (1 minute ON per every 4 minutes).
It’s very important to realize that the energy consumption will vary greatly from day to day. Indeed, there are many variables that affect how hard the air conditioner has to work (duty cycle) to maintain a certain temperature:
Always read the manual and make sure you meet the requirements. For example, a fridge evacuates the heat through its coils in the back. If the fridge is installed in a cabinet without any ventilation, the heat pumped out of the fridge has nowhere to go and the coils won’t be able to do their job.
A heat pump evacuates heat through its coils; if these coils are full of dust, efficiency is greatly reduced and energy consumption increases. Follow the maintenance schedule prescribed by the owner’s manual!
The ambient temperature outside has a massive impact on energy consumption. To make an analogy with our fridge, we observed that the duty cycle can get as low as 10% in winter and goes as high as 75% on a very hot summer day. Huge difference!
Trying to maintain the interior of the van at a very low temperature will obviously consume way more energy than at a moderate temperature.
Size matters! It takes much less energy to cool a fridge (~5.8 cu. ft.) compared to a small van (~250 cu. ft.) or a larger van (~500 cu. ft.)
Compared to a fridge, a van is poorly insulated and the heat transfer rate is way higher. That’s especially true for the windows, so investing in good insulated window covers is a must.
Parking directly under the sun is good for solar charging, but quite bad for heat; especially for dark colored vehicles…
Opening the doors
It’s normal having to enter/exit the van in our daily life. But each time, a lot of heat is transferred and the A/C has to work harder to compensate.
The Nomadic Cooling Co. air conditioner fits into a “traditional” 14″x14″ cutout; that’s the same cutout as for a Maxxfan roof fan (see our installation guide). We personally didn’t install an A/C on our van because we’re lucky enough to have the flexibility to follow the seasons (in other words: drive north in summer!). That being said, here is some info to get you started:
4.1- Air Conditioner Adapter
To create a perfect seal and prevent water infiltration, the air conditioner needs to be installed on a perfectly flat surface. The roof of most common vans (Transit, Sprinter, ProMaster, etc) have corrugations on them, but the use of an Air Conditioner Adapter Kit that’s model-specific (Transit, Sprinter, ProMaster) will solve that issue:
The roof adapter (gasket) creates a perfectly flat surface:
The kit includes framing strips to increase support for the extra weight of the A/C:
The framing strips are installed inside the van if there is 18″ or more spacing between the beams:
Check out Nomadic Cooling Co.’s blog for more information on installation: