Every Nomadic Cooling air conditioner, the X2 Helix Gen II, X3 Helix and S1 Helix, comes in a 12V and a 48V version. The cooling is in the same range either way. What changes is the current, and current decides your cable size, your fuse, your voltage drop and how hard your battery works. This guide uses Nomadic's own amp figures and install notes to show what 12V and 48V mean in a real build, and how to pick.
Same power, very different current
Power is volts times amps. Quadruple the voltage and you need roughly a quarter of the current for the same watts. Nomadic's published figures show the effect clearly:
| Model and figure | 12V | 48V |
|---|---|---|
| X2 Helix Gen II, rated maximum | 64 A (947 W) | 19 A (986 W) |
| X2 Helix Gen II, rated ECO current | 38 A | 9 A |
| X2 Helix Gen II, Full AC planning average | ~59 A (~871 W) | ~17.7 A (~913 W) |
| X3 Helix, Full AC (provisional) | ~88.6 A (~1,297 W) | ~25.2 A (~1,386 W) |
| X3 Helix, ECO (provisional) | ~61.2 A | ~10.3 A |
| S1 Helix, Full AC (planning) | ~61 A (~879 W) | ~17 A (~948 W) |
| S1 Helix, ECO (planning) | ~33.7 A | ~8 A |
The X3 and S1 figures are Nomadic's provisional and planning estimates pending certification. Use them for planning, not final electrical design, and confirm against the manual that ships with your unit.
What the current means for wiring
Cable size
Nomadic's own X-Series DIY install kit for the X2 and X3 shows the difference in copper. It uses a 15 ft power harness in 2 AWG for 12V and 24V systems, and 8 AWG for 48V. 2 AWG is thick, stiff cable that takes planning to route through a van wall or roof; 8 AWG is far easier to run. (We do not stock that kit; it is a useful reference for what Nomadic considers right for a 15 ft run.)
Voltage drop
For a given cable, the voltage lost along it rises with current. Nomadic's S1 install notes ask you to size cable to keep voltage drop at or below 3%. On a 12V system, 3% is only about 0.36 V; on 48V it is about 1.44 V. So the 12V build has to deliver three to four times the current while losing a quarter of the volts. That is why 12V air conditioner wiring needs heavy cable kept short, and why Nomadic's 48V figures are friendlier to long runs.
Fuses and breakers
Nomadic's S1 instructions call for a 100 A breaker or fuse on 12V, or a 30 A breaker or fuse on 48V, on the positive line within 18 in of the battery. For the X2 and X3, Nomadic says to install overcurrent protection per the X2 or X3 manual; its install kit does not include a fuse or holder. Follow the manual for your unit and your battery's BMS limits. Our guide to wire gauge, fusing and torque covers the general rules for 12V installs.
Low-voltage protection
Big DC loads pull battery voltage down, more so on 12V. Nomadic's X2 shows onboard voltage and cutoff readouts, and the S1 has adjustable low-voltage protection with a live voltage display, so you can set the floor that protects your bank.
When 12V makes sense
- You already have a 12V house bank, charger, alternator charging and solar, and you do not want to rebuild the system.
- The cable run from battery to air conditioner is short.
- You are choosing an X2 or S1, the lower-draw units, and mostly running ECO.
Nomadic's own summary for the S1: 12V means common parts, simple integration and a good match for standard house banks and moderate rest windows. The X2 page notes it works with a modest 12V battery bank.
When 48V makes sense
- You are designing a new electrical system around a large lithium bank, especially for long, hot nights.
- You want the X3, whose 12V Full AC figure of about 88.6 A (provisional) is the highest current in the line.
- The battery is a long way from the roof opening, so voltage drop on 12V would force very heavy cable.
Nomadic says 48V gives lower current draw and smaller gauge runs, and suits long hot overnights. Remember that a 48V unit needs a 48V supply. If the rest of your rig stays at 12V, you will need to plan how those 12V loads are fed, which is a whole-system decision, not just an air conditioner choice.
What about 24V?
Nomadic says the X2 Helix Gen II is not offered in 24V; it comes in 12V and 48V only, and the X3 and S1 are listed in 12V and 48V too.
Does 48V give longer runtime?
Not on its own. Runtime depends on how much energy the bank stores. A 100 Ah 48V LiFePO4 bank and a 400 Ah 12V bank hold about the same usable energy, about 4,608 Wh at 90% (100 x 51.2 V x 0.9, or 400 x 12.8 V x 0.9). What 48V does is deliver that energy with less current, so less is lost as heat in the cable. For model-by-model runtimes see how much battery you need to run a Nomadic air conditioner, and model your own system in the solar and battery calculator.
Choosing your Nomadic unit by voltage
| Model | 12V version | 48V version |
|---|---|---|
| X2 Helix Gen II rooftop | White · Black | Black |
| X3 Helix rooftop | White · Black | Black |
| S1 Helix split | Black · White | Black · White |
Not sure which one? Compare all three in Nomadic X2 vs X3 vs S1.
Questions
Can I run a 48V Nomadic unit from a 12V battery?
The 48V models are built for a 48V DC supply. If your bank is 12V, the 12V model is the straightforward choice. Anything in between, such as a converter, has to carry the full 12V current anyway, so talk to us before you plan it.
What cable size do I need for a 12V Nomadic rooftop unit?
It depends on the length of the run and the fuse rating in Nomadic's manual. As a reference point, Nomadic's own 15 ft install harness is 2 AWG for 12V and 8 AWG for 48V.
Does a 12V unit cool less than the 48V one?
Not much on the X2: Nomadic's planning averages are about 8,950 BTU/hr on 12V and about 9,484 BTU/hr on 48V on Full AC. The X3's provisional figures actually show the 12V version higher on both modes.
Where does my order ship from?
All Nomadic units ship from our warehouse in Upland, California, with free shipping to the lower 48 states. Shop the full Nomadic Cooling range.