Sleep apnoea affects roughly one in ten Australians, and for the caravanning community, a CPAP machine raises a very real question: can I still go off-grid?

Yes. Confidently, reliably, every single night. But only if your power system is built correctly. This guide covers what a CPAP actually draws, what inverter you need, how to size your battery and solar, and what charging system is best suited. 

[IMAGE SUGGESTION: Hero image of a caravan set up at a remote bush camp at dusk, warm lighting inside, solar panels visible on the roof]

⚡ Key Takeaways

  • ⚡ A CPAP with heated humidifier can draw 40-80Ah per night
  • ⚡ You must use a pure sine wave inverter for any 240V CPAP
  • ⚡ A 200Ah lithium battery is our recommended minimum size
  • ⚡ Running your CPAP via its 12V DC adapter (bypassing the inverter) is more efficient 

How Much Power Does a CPAP Actually Use?

The answer depends on whether you're using a heated humidifier and your prescribed pressure setting. The humidifier is where most people get caught out, as it can double or even triple your overnight draw, and for many users it's not optional.

 

Configuration Approx. Wattage Nightly Draw (8 hrs)
CPAP Power Consumption Reference
CPAP without humidifier 30–60W 20–40Ah
CPAP with heated humidifier 60–120W 40–80Ah
CPAP + humidifier via pure sine inverter (inc. losses) 60–120W + ~10% 44–88Ah
NotePlease refer to your model for exact specifications.
CPAP Power Consumption Reference
Without Humidifier
Approx. Wattage 30–60W
Nightly Draw (8 hrs) 20–40Ah
With Heated Humidifier
Approx. Wattage 60–120W
Nightly Draw (8 hrs) 40–80Ah
Via Pure Sine Inverter (inc. losses)
Approx. Wattage 60–120W + ~10%
Nightly Draw (8 hrs) 44–88Ah
NotePlease refer to your model for exact specifications.

 

Plan your system around your actual usage. If you run a humidifier, use 80Ah per night as your baseline — then add your fridge, lights, and devices on top.

[IMAGE SUGGESTION: CPAP machine on a caravan bedside table with humidifier and hose visible]

Inverter: Pure Sine Wave Only

If your CPAP runs on 240V, you need an inverter. But the type matters enormously. There are two kinds sold for caravan use:

  • Pure sine wave — clean AC output, identical to grid power. Safe for medical devices.
  • Modified sine wave — a cheaper, stepped approximation. Can cause erratic pressure delivery, motor wear, and machine failure in CPAPs. Will likely void your warranty.

The modified sine wave inverter is the single most common cause of the "inverter cut out at 3am" complaint in the caravan community. The CPAP draws extra current trying to compensate for the poor waveform, voltage drops faster than expected, and the inverter shuts down. Pure sine wave only.

For a CPAP without humidifier, 300W is sufficient. With a heated humidifier, go to 500W. AllSpark's pure sine wave inverter range is built for continuous, sensitive loads in remote conditions. Browse AllSpark inverters here.

Tip: If your CPAP machine has a 12V DC input, running it via your machine's travel adapter (bypassing the inverter) saves 15–25% in conversion losses overnight. Check with your CPAP supplier for the correct model-specific cable — these are not universal, and the wrong one can cause damage. Note that most heated humidifiers cannot run on 12V DC.

[IMAGE SUGGESTION: AllSpark pure sine wave inverter mounted in a caravan power bay]

Battery: Size It for the Real Numbers

This is where most off-grid CPAP setups fall short. A 100Ah AGM battery sounds adequate — but AGM should be kept above 50% charge to protect battery life, which means only ~50Ah of usable capacity. That's barely one night of CPAP, before you've powered anything else.

Lithium (LiFePO4) batteries are a better match for this use case. They're lighter, charge faster, and we recommend operating them to around 80% depth of discharge to maximise longevity — though unlike AGM, they're not harmed by deeper discharge if you occasionally need it. That gives a 200Ah lithium battery a comfortable working capacity well in excess of what most AGM banks can reliably deliver.

Battery Rated Capacity Recommended Working Capacity CPAP nights (60Ah/night incl. other loads)
100Ah AGM 100Ah ~50Ah <1 night
200Ah AGM 200Ah ~100Ah 1–1.5 nights
100Ah LiFePO4 100Ah ~80Ah 1+ nights
200Ah LiFePO4 200Ah ~160Ah 2–3 nights

For reliable off-grid CPAP use — including a fridge and everyday loads — a 200Ah LiFePO4 is our recommended starting point. AllSpark lithium batteries are available in standard and waterproof chassis-mount configurations, built for Australian touring conditions. Browse the AllSpark lithium range here.

[IMAGE SUGGESTION: AllSpark lithium battery installed in a caravan battery bay]

Charging: Solar and DC-DC

A solid battery is only useful if you can reliably recharge it. For most caravanners, that means two charging sources working together.

Solar handles daytime recovery. As a practical guide, 300W of fixed roof panels is sufficient to recover an 80–100Ah overnight draw in a typical Australian day. For extended travel through high-cloud regions (tropical north in the wet, higher altitude in winter), adding a portable folding panel gives you the flexibility to position for best output when the roof panels are under shade or overcast. Both AllSpark fixed glass panels and folding portable panels are suited to this. Pair them with a quality MPPT solar controller — REDARC and Victron both offer well-regarded options — to maximise harvest and ensure the correct charge profile for lithium. Browse MPPT controllers here.

DC-DC charging handles driving days. A DC-DC (battery-to-battery) charger ensures your house battery gets a proper multi-stage charge from the alternator — critical for lithium batteries, which a simple isolator relay won't charge correctly. REDARC and Victron both make reliable units for this application. Browse DC-DC chargers here.

[IMAGE SUGGESTION: Rooftop solar panels on a caravan at a bush camp, portable folding panel positioned in foreground]

Ready to Go Off-Grid With Your CPAP?

A CPAP diagnosis doesn't mean you're stuck to powered sites. The right system — lithium battery, pure sine wave inverter, adequate solar, and a DC-DC charger for driving days — means you can free camp as long as you like, wherever you like, and wake up every morning having had a full night's therapy.

Not sure where to start? Call us. We'll talk through your machine, your loads, and how you travel, and give you a straight answer on what you need — no upsell, no vague estimates.

[IMAGE SUGGESTION: Grey nomad couple relaxed outside their caravan at a remote camp, sunrise, conveying freedom and confidence]