[Note: medical devices are often critical to life support. Seek qualified professional assistance with any alternative means of powering your devices.]
A growing number of historic re-creators and re-enactors have medical conditions that require using electrically powered assist devices. One of the most common medical device that requires more than a handful of “C-cell” batteries is the CPAP machine.
Dealing with a CPAP machine in a camping environment can be tricky. Some camping events have special areas where electricity is available. Some larger SCA (Society for Creative Anachronism) events such as Pennsic and Gulf Wars have handicapped camping areas set aside for any number of medical needs. Campers in these areas can charge batteries and electric wheelchairs within convenient distance of their tents.
Suppose that where you want to camp doesn’t have the infrastructure to support electricity?. What can you do then?
RVs and camper-trailers can have an on-board generator to power your medical devices. But, running a generator all night might make you unpopular with other campers. Fortunately there’s another answer – batteries. Big batteries. And an inverter. Our old RV was set up to allow us to camp comfortably without power for about 2 1/2 days, and more if we were conservative.
Another option is purchasing a portable battery powered CPAP machine that will operate for one night on a single charge. Transcend II Travel CPAP Machine is one such machine. In this case, bring the number of batteries that you will need for the duration of the event, or arrange to charge batteries during the day. Each battery costs from $225 to $350 depending on the expected number of nights that the CPAP machine must be powered. But, even the $350 battery will only provide 2 nights of use for that specific CPAP machine. By comparison, some older CPAP machines that are powered by household power can consume many times that amount of power. A friend who used a CPAP machine could operate his CPAP machine for two nights by using a 30Ah deep cycle battery and a high efficiency inverter. People who must also use an oxygen concentrator must be connected to conventional 120V power (wall outlet in a house etc) due to the higher power demand from the oxygen concentrator.
For longer term camping, multiple deep cycle batteries combined with an inverter will often permit you to charge the batteries at home before you camp so no charging is required during the event. The selection of deep cycle batteries is nearly endless. Sealed AGM batteries are good because you can’t spill acid from them. You can buy these batteries in capacities of more than 30Ah (up to 125Ah in one barrey) – much more power than the batteries used for the Transcend II CPAP machine. If you have the ability to store and move flooded cell batteries, a deep cycle battery such as those sold by Trojan Battery are good relatively low cost alternatives. Think about setting up a purpose built or bought rolling cart or dolly to move your batteries, some of them are too heavy to be casually moved by your average person.
Another option, which may not be allowed in some locations, is using a small, super-quiet generator to charge batteries, or your RV batteries, during the day.
All you need to do is determine the amount of battery that you need for your specific CPAP machine.
Next: How to Size Your System