CPAP machines (Constant Pressure Air Pump) are quite common with many of our customers, needing to be used during sleep and/or during the day.
These are generally a 240V device designed for use from domestic mains power. In a caravan, you need to run them through an inverter – which is a device that takes 12v battery power, and produces 240V main power. In selecting an inverter, you need to ensure you get the correct size unit.
In general, a CPAP machine will consume about 5-6 Amps at 12V while running. If you run this for 8 hours, this is approx 48Ah of power, and equates to the usable capacity of a single “normal” caravan battery. (ie a 100Ah deep cycle caravan battery can provide up to 50Ah of power before needing to be recharged).
Therefore, if you have just one battery, you would need to be able charge it each day with solar being the most common option when away from powered sites. You would need a minimum of a 150W panel, and approx 5.5 hours of sunlight per day. Of course, 2 batteries and 2x 150W solar panels would be a better option.
There are also 12V versions of CPAP machines available, and consume approx 1.5-2.5A of power – which is considerably less and reduces load on your 12V system compared with the inverter version.
Inverter Recommendations for CPAP machines
- Use a “Pure Sine Wave” inverter.
- Look at “Wattage” or “Amperage” rating of your 240V CPAP machine. Most consume around 0.3A at 240V which is approx 72W (A x V = W)
- Get an inverter larger than this Wattage. E.g. minimum size for above would be 100W inverter.
- A good common size inverter for use in a caravan in 300W Pure Sine Wave, and would allow you to run other devices like a laptop too.