Updated 26 May 2017
Until recently sleep apnoea machines for camping drew too much energy for use on solar. It’s now feasible using the approach in this article.
Sleep apnoea machines are used for breathing, snoring and sleep disorders. They are large volume, low pressure air pumps. Some include humidifiers, others heat the supplied air. Most pre 2012 sleep apnoea machines draw a lot of energy. If seeking to use one for camping it will probably be necessary to replace it by one of the latest units. These draw far less energy.
Anyone who has or suspects they have a breathing disorder, sleep apnoea syndrome, sleep disorder, snoring or similar conditions should initially consult a doctor.
Men (in particular) are more likely to accept their need for a CPAP machine if their partner is supportive. Pic: SleepClinics Inc.
CPAP continuous positive airway pressure machines deliver constant pressure air that keeps the upper airway open. This prevents the narrowing of that airway if the upper respiratory tract muscles relax. A variant, automatic positive airway pressure (Auto-CPAP), optimises air pressure if CPAP is not effective. The (BiPAP) variant reduces out-breath pressure. For the latest non-heater/non-humidifier units, energy draw relates to air pressure required. Your doctor will advise.
Sleep apnoea machines for camping – energy draw
The typical energy draw of (non-heater) post 2014 CPAP units is 8-18 watts (0.65-1.5 amps at 12 volts). Running for eight hours a night thus requires 5.2-18 amp hours. A 12 volt deep cycle battery of 20 to 50 amp hours provides that with ease. Such sleep apnoea machines for camping or in RVs generally can readily be powered via solar.
Sleep apnoea machines run from 230 (or 110) volts. A few have an inbuilt inverter that enables them to run from 12 volts. Most however require a separate inverter, (of about twice the machine’s draw in watts), to run from 12 volts.
If driving most days, the battery will recharge from the vehicle alternator in an hour or two. This is best done using a dc-dc alternator charger, or battery management system. See associated Articles on this website.
If camping in summer, it is feasible to recharge these basic types of machines from solar alone. Those medically-essential, however, must have 100% reliable power. For an 8 watt unit, a single 100 watt solar module is adequate almost anywhere. An 18 watt unit requires two by 100 watt solar panels. This is far more than needed for general use. In conjunction with that battery, however, it copes for several days of little sun. Also needed is a high quality solar regulator.
Heated humidifier units
These draw 30 to 72 watts (2.5-6.0 amps). Assuming eight hours a night, and allowing for charging losses etc, this is 300 watt hours (25 amp hours) to 750 watt hours (65 amp hours). This necessitates dedicated battery capacity of 75-150 amp hours. This is still feasible with the larger caravans and motor homes. With smaller RVs it is advisable to use LiFePO4 batteries. These are a third or so of the weight of conventional batteries (but more costly).
If advised that the heated humidifier is essential, it’s advisable to charge the battery via an inverter-generator. The 1.0 kW Honda or Yamaha will do fine. Do this via a multi-stage mains charger from the generator’s 230 volt outlet. See (Battery Charging via Generator). This provides two choices. To run the sleep apnoea machine the battery alone. Or, if there are battery problems, directly from the generator’s 12 volt output . It is worth supplementing this via solar. The draw, however, (at least of the 750 watt hour unit), is too high for solar alone. Doing that requires far higher margins of safety than normally required.
Setting up sleep apnoea machines for camping
Setting up sleep apnoea machines for camping thus requires an ultra-conservative approach. It far exceeds that normally recommended for general RV use. If doctors advise an apnoea machine is vital, do not cut back on any part of the system.
It is vital (in my opinion) to use a solar system (including battery) dedicated for that machine. It must also be conservatively designed, and competently installed. If however, formally advised that usage is optional run it from an existing system with capacity accordingly increased.
Typical sleep apnoea machine mask. Pic: courtesy thecpapshop
For sleep apnoea machines for camping, consider having a fully charged battery in reserve. This should be an AGM or LiFePO4. As long as first fully charged, both will most of that charge for six or more months.
Vendors in this field claim to be able to advise on specific CPAP machines. Here again, always obtain a doctor’s advice.
Sleep apnoea machines for camping – further information
Details of designing and installing the systems required are in my Solar that Really Works (for cabins and RVs), Solar Success (for homes and properties), Caravan & Motorhome Electrics, and the Caravan & Motorhome Book. Camper trailers owners are advised to consult the Camper Trailer Book. All are written in plain English. For information about the author please Click on Bio.
Always follow the sleep apnoea machine manufacturers’ instructions in all aspects.
Disclaimer: The author has no medical qualifications. Queries relating to medical aspects must be directed to doctors and or specialists in this field.
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