Nomadic Cooling makes three DC air conditioners: the compact X2 Helix Gen II rooftop unit, the larger X3 Helix rooftop unit and the S1 Helix split system. All three run straight from a 12V or 48V battery bank with a PWM compressor, and all three work with the Helix app. The right one depends on four things: where it can go on your rig, how much cooling you need, how many amps your battery bank can supply, and whether your build is 12V or 48V. This guide puts Nomadic's own figures side by side.
The short answer
- Pick the X2 Helix Gen II for a camper van, truck camper or small trailer where roof space and battery capacity are tight. It is the smallest and lightest of the three and has the most complete published figures.
- Pick the X3 Helix for a larger cabin, or a coach builder who wants RV-C integration. Its figures are provisional, and the 12V model draws the most current of the line.
- Pick the S1 Helix split when nothing can go on the roof: sleeper cabs, rigs with a full solar roof, or builds that need to keep their height. It needs a rear-wall mounting spot and a refrigeration technician for the final charge.
Nomadic X2 vs X3 vs S1 at a glance
Nomadic publishes "planning averages" measured across 70 to 100+°F test ranges. These are more useful for battery planning than a single peak number. The X3 and S1 figures are labelled by Nomadic as provisional (X3) or planning (S1) estimates pending certification, so treat them as planning values, not final ratings.
| X2 Helix Gen II | X3 Helix | S1 Helix split | |
|---|---|---|---|
| Layout | Rooftop, 14 x 14 in opening | Rooftop, 14 x 14 in opening | Rear-wall condenser + interior evaporator |
| Voltages | 12V or 48V | 12V or 48V | 12V or 48V |
| Full AC, 12V | ~8,950 BTU/hr, ~871 W, ~59 A (planning average) | ~12,893 BTU/hr, ~1,297 W, ~88.6 A (provisional) | ~10,216 BTU/hr, ~879 W, ~61 A (planning) |
| ECO, 12V | ~5,864 BTU/hr, ~526 W, ~35.7 A | ~10,503 BTU/hr, ~899 W, ~61.2 A (provisional) | ~6,304 BTU/hr, ~486 W, ~33.7 A (planning) |
| Full AC, 48V | ~9,484 BTU/hr, ~913 W, ~17.7 A | ~11,671 BTU/hr, ~1,386 W, ~25.2 A (provisional) | ~11,132 BTU/hr, ~948 W, ~17 A (planning) |
| ECO, 48V | ~5,834 BTU/hr, ~452 W, ~8.7 A | ~5,216 BTU/hr, ~523 W, ~10.3 A (provisional) | ~6,875 BTU/hr, ~451 W, ~8 A (planning) |
| Size | Compact X-Series rooftop | 31.5 x 30.9 in footprint, 7.36 in above the roof | Condenser 17.83 x 23.68 x 8.36 in; evaporator 24.26 x 13.07 x 7.52 in |
| Weight | 42.8 lb | Check with us (Nomadic lists two figures) | About 74.9 lb shipping weight, both pieces boxed |
| Refrigerant | R1234yf | R1234yf | R1234yf or R134a, charged on site |
| Extras | Gen II base with leveling feet and water-management fins | RV-C through the optional Helix AC Controller | Adjustable low-voltage protection, display-only panel |
The X2's rated maximum, the number most spec sheets quote, is 9,586 BTU/hr at 947 W and 64 A on 12V, and 9,974 BTU/hr at 986 W and 19 A on 48V. Nomadic lists ECO current at 38 A (12V) and 9 A (48V).
Where it goes: roof or rear wall
The X2 and X3 both drop into the industry-standard 14 x 14 in roof opening, the same cutout most RV rooftop air conditioners use. Nomadic allows about plus or minus 1/2 in on the X2 opening and ships a full-size 1:1 cutout template in the box. The X2 is the compact choice: Nomadic designed it to leave more roof room for solar panels, fans and racks. The X3 is the larger rooftop package, at 31.5 by 30.9 in and 7.36 in above the roof.
The S1 is not a rooftop unit at all. Its condenser mounts outside on a rear wall or bulkhead, and the evaporator mounts inside near where you sleep, with the lines and wiring passing through a 2.25 in hole. Nomadic asks for about 4 in of free space around the condenser vents, about 6 in around the evaporator, and a mounting slope of no more than 5 degrees. That makes the S1 the one to choose if you have no roof space left, or if a roof unit would put you over a height limit.
How much cooling you need
For small cabins, the X2 on ECO runs at roughly 5,900 BTU/hr on Nomadic's planning average, and about 9,000 BTU/hr on Full AC. The X3's provisional 12V figures are the highest of the line, at about 12,900 BTU/hr on Full AC, which suits a bigger interior or a hotter climate. The S1 sits between the two on 12V and focuses its air on the bunk or bed area.
Cabin size is only part of it. Insulation, window covers, sun on the roof and humidity change the result more than most people expect, and Nomadic says so on its product pages. For a general sense of BTU by rig length, see our RV air conditioner BTU sizing guide, then use the Nomadic figures above to check the battery side.
What your battery bank can carry
This is where most DC air conditioner plans succeed or fail. On a 12V system, the X3 on Full AC draws about 1,297 W (provisional), close to 50% more than the X2's 871 W. Over a night that difference is hundreds of amp-hours. As a quick reference, a 400 Ah 12V LiFePO4 bank gives about 4,608 Wh usable (400 x 12.8 V x 90%). That is about 8.8 hours of the X2 on ECO at its 526 W average, or about 5.1 hours of the X3 on ECO at 899 W, if the unit runs at that average all night with no solar coming in.
We work through every model and bank size in how much battery you need to run a Nomadic DC air conditioner, and you can model your own loads in our solar and battery calculator.
12V or 48V
All three come in 12V and 48V. The cooling is similar; the current is not. The X2 on Full AC draws about 59 A at 12V and about 17.7 A at 48V on Nomadic's planning averages. Lower current means smaller cable and fusing and less voltage drop over the run. If your house bank is already 12V, the X2 is the easiest fit. If you are building a new electrical system around a big battery, or choosing the X3, 48V is worth a hard look. The X2 Gen II is not offered in 24V. More detail in our 12V vs 48V DC air conditioner guide.
Controls and smart features
All three are built for the Helix app on a phone, tablet or watch for schedules, scenes and pre-cooling, and all three keep local controls. On the X2, Nomadic says the Helix Pulse touchscreen hub is not required for app control; it adds a wall screen for cameras, leak sensors, tank levels and switches. The X3 adds RV-C integration through the optional Helix AC Controller, aimed at coach builders with multiplex panels; Nomadic lists direct third-party coach-system integration as still on its roadmap. The S1 uses a display-only interior panel, buttons behind the evaporator cover and an included IR remote; Nomadic calls the app its primary control but lists Helix app control as "available separately" in the box contents, so ask us what your setup needs.
Installation effort
The rooftop units follow the familiar 14 x 14 in install: template, gasket, crossbars, DC wiring and faceplate. Nomadic says a skilled DIYer can do it, provided they are comfortable sealing a roof and sizing DC wiring and fusing. See our Nomadic rooftop install guide. The S1 needs more work: two mounting locations, a 2.25 in wall pass-through, cut-to-length refrigerant lines, and a licensed technician to evacuate the system and charge it. Nomadic puts a typical professional S1 install at about a workday per truck.
Questions
Is the X2 Helix you sell the Gen II?
Yes. Every X2 Helix we list is the current-production X2 Helix Gen II, with the updated shroud, revised base with leveling feet and directional water-management fins.
Why are the X3 and S1 numbers marked provisional?
Nomadic labels them as provisional or planning estimates from its X-Series and S-Series comparison data and says certified figures will replace them after testing. We quote them that way and will update them when Nomadic does.
Can an S1 cool a camper van?
Nomadic designed the S1 for sleeper cabs first, but says it also suits vans, RVs and expedition trucks that want interior-mounted cooling and a clear roof, as long as there is rear-wall space and a clean route for the lines.
Where do Nomadic units ship from?
Every Nomadic Cooling unit we sell ships from our warehouse in Upland, California, with free shipping to the lower 48 states. Not sure which model fits? Send us your rig, roof layout and battery bank and we will help you choose. Shop the full Nomadic Cooling range.