by Collyn Rivers
Sleep Apnoea Machines for Camping
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 assist people with 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 substantial energy. If needing to use one for camping it may need replacing by a current unit. Most draw far less energy.
Anyone who has or suspects they have a breathing disorder should initially consult a doctor.
A typical CPAP machine delivers constant pressure air that keeps one’s upper airway open. This prevents that airway narrowing 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 battery of 30 to 50 amp hours provides that with ease. Such sleep apnoea machines for camping, or in RVs generally, can readily be powered by 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 to run from 12 volts. If doing so you need on of about twice the machine’s draw in watts. This is because most draw more energy for a few seconds when switched on.
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 modules. 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 units draw 30 to 72 watts (2.5-6.0 amps). Assuming eight hours use 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 motorhomes. With smaller RVs it is advisable to use LiFePO4 batteries. These are a third or so of the weight of conventional batteries.
Heated humidifiers draw substantial energy. If medically advised that heating is essential, you are likely to need to charge a larger 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).
Doing this provides two choices. The first is to run the sleep apnoea machine from the battery alone. If, however, there are battery problems, to run the machine directly from the generator.
It is worth supplementing this via solar. The draw, however, (at least of the 750-watt hour unit), is far too high for solar alone. Doing that requires higher margins of safety than normally required.
Setting up sleep apnoea machines for camping
Setting up sleep apnoea machines for camping requires an ultra-conservative approach that far exceeds that normally required. 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 to 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 increased accordingly.
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, an AGM will retain most of that charge for six or more months. A LiFePO4 will do so for even longer.
Vendors in this field claim to be able to advise on specific CPAP machines. Here again however, always initially 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 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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