Camping with a CPAP device can make you feel like you are tied to a power post. Being in the RV industry as long as I have, I have seen people carry additional batteries, seperate inverters, extension cords, small generators and other confusing, ineffiecent products in persuit of being able to camp off-grid with their CPAP device.
I have sourced the proper parts to accomplish this task very efficiently and elegently. Best of all, worst case scenario - it only requires a simple DIY install of a 12v power socket! You will find Amazon affilate links throughout the article linking to the products I recommend for the project!
Besides the obvious concerns of having seperate batteries and rogue electrical cabling strung throughout the interior of your RV, the issue with utilizing an inverter to power your CPAP device is the losses incurred converting power from DC (in the battery) to AC (through the inverter) and back to DC (through the CPAP power brick). All of the CPAP devices I have encountered run on 12v or 24v DC power. When using a CPAP device at home, the power cord plugs into a standard 120v AC outlet and the plastic box that is inline with the cord is converting AC power to DC. In a camper being used off-grid, the entire electrical system is already DC. If we can pass the existing DC power straight through to the CPAP two conversions can be avoided resulting in somewhere between 10-20% power savings!
Some newer campers come with a 12v cigarette lighter socket in the bedroom area, others may have a USB charging station, but almost all campers have some sort of 12v light fixture near the bed. If you dont already have a 12v socket, one can be easily added by connecting to a existing 12v device near by. Typically, the wiring used in campers is more than adaquate enough to handle the additional load of the CPAP device, but you must always do your research to make sure you arent overloading the circuit.
After you have a 12v power socket, I strongly suggest identifying which fuse in your fuse panel supplies that socket with power and replacing the fuse with an identically sized automatic resetting circuit breaker. Most 12v circuits in campers are 15a. We want to replace the fuse with a auto resetting circuit breaker as a safety measure. If there would be a problem with the circuit that would normally cause the fuse to blow (and the CPAP to shut down), the circuit breaker will disconnect and reconnect until the problem is resolved.
With the addition of a solar panel to replenish the battery after a night of running the CPAP, boondocking becomes much less restricting. Talk about a whole new way to cut the cord!