CPAP in a Semi Truck: The 12V Power Guide (2026)

⚠️ Not medical advice. This guide covers 12V power supply for CPAP machines only. Sleep apnea diagnosis and CPAP pressure settings require a doctor — never adjust your prescription based on a gear guide.

If you run a CPAP in the sleeper, the question isn't whether it works — it's how many nights your batteries last. Here's the math, the 12V setup that wastes the least power, and what size power station you actually need.

This is general information about 12V power, not medical advice. Talk to your doctor about sleep apnea treatment. Never change your CPAP pressure settings based on this guide.

How much power does a CPAP draw?

Typical ranges — check your machine's label for exact figures. (ResMed publishes 53W typical / 104W peak for the AirSense 10; see the manufacturer's user guide, Technical Specifications.)

Setup	Typical draw
CPAP, no humidifier, no heated hose	30–60W
CPAP + heated humidifier	60–90W
CPAP + humidifier + heated tubing	90–150W
Travel CPAP (no water humidification)	5–20W

The heated humidifier is the big draw — it's a resistive heating plate. Turning it off can cut consumption by half or more. Heated tubing adds further draw on top.

12V DC vs inverter: DC wins by ~20%

Most CPAPs run on 12V or 24V DC internally. The wall plug converts AC to DC — so running through an inverter means converting DC→AC→DC, wasting power as heat in both directions.

12V DC converter cable (brand-specific, e.g. ResMed Air10 DC/DC converter): roughly 20% more efficient than an inverter setup. Plugs into a 12V outlet or direct to battery.
Inverter: works with any CPAP, but wastes energy. If you go this route, use a pure sine wave inverter sized close to your actual draw — a 200W PSW inverter feeding a 60W CPAP runs more efficiently than a 1000W unit idling.

One user's reported experience (ResMed AirSense 10, 400Wh battery — not lab-tested): heated hose + humidifier lasted 7.5 hours on AC vs 14 hours on 12V DC. No humidifier: 30.5 hours on AC vs 45.5 hours on DC.

The battery math

Formula: Runtime (hours) = Battery capacity (Wh) ÷ CPAP watts

Worked examples for an 8-hour night:

CPAP setup	Watts	Wh needed (8h)	Minimum power station
No humidifier	40W	320Wh	500Wh class
Heated humidifier	75W	600Wh	1000Wh class
Humidifier + heated tube	120W	960Wh	1000Wh+ class

Add 20% margin for inverter losses if you're not using DC, and note that cold reduces usable battery capacity (lithium handles cold better than lead-acid, but all chemistries derate).

Truck batteries vs dedicated power station:

Running off the truck's starting batteries overnight risks a no-start in the morning. Not recommended without a low-voltage cutoff.
A dedicated LiFePO4 power station isolates your CPAP from the starting batteries. Every pick in our power station guide is LiFePO4 — the right chemistry for nightly cycling.
Recharge the station while driving via 12V car charging or the alternator.

What you need

12V DC converter cable for your specific CPAP model (most efficient path)
Portable power station, sized from the table above — see our portable power station buying guide (all picks LiFePO4)
Inverter (only if you can't get a DC cable for your model) — size it close to your draw; see our inverter size calculator
12V wiring safety: match wire gauge and fuse to the load — see our 12V outlet safety guide

Winter angle

Cold sleeper + heated humidifier = maximum draw. The humidifier works harder in dry winter air, and battery capacity drops in the cold. Size up one class if you run heat + humidity through a Canadian winter. A diesel bunk heater warming the cab reduces the humidifier's workload indirectly.

FAQ

Can I run my CPAP off the truck's 12V outlet?

If the outlet is rated for the draw (most are 10A/120W fused) and you use a DC converter cable, yes for the CPAP itself. But it drains the starting batteries — a dedicated power station is safer for overnight use.

Will a 300Wh power station run my CPAP all night?

Only without the humidifier (30–40W × 8h = 240–320Wh, right at the edge). With humidifier, no — you need 600Wh or more.

Do I need a pure sine wave inverter?

For CPAPs, yes — modified sine wave can damage the power supply or cause erratic behavior. This is one case where pure sine wave is non-negotiable.

Can I charge the power station while driving?

Yes — 12V car charging from the cab outlet, or faster via a DC-DC charger wired to the alternator. Most stations recharge fully during a driving shift.

General information, not medical advice

This guide covers 12V power supply for CPAP machines only. Wattage figures are typical ranges from manufacturer specs and user measurements; individual machines vary — check your machine's label. Sleep apnea diagnosis and CPAP pressure settings require a doctor. Never adjust your prescription based on a gear guide.