So I have begun to camp with scouts and leaving my cpap at home is not a choice. I have to take it. I spotted the LiIon Batt packages and thought I can do better. The LiIon batts are expensive even if ordered from the Chinese manufacturer (I checked). I decided to go with deep cycle sealed lead acid batts instead.
I purchased two sealed LA batts from amazon. Each is 12v and 12ah. The LiIon batts were only 7.5ah. I also procured another cpap like i have at home and removed the humidifier. Both batts and the Cpap fit nicely into a marine batt box I purchased at walmart.
I added a 12v multiplier device that fits in the cup holder of your car. This added the capability of two 5v usb ports as well as 2 12v cig plugs.
After cutting the hole in the marine box and fabricating some brackets to support the extender I fit it all together. Nice.
I then modified the wiring on the 12v multiplier to separate one cig plug all by itself. This will be the cpap side. The other side includes the 12v cig plug and the 2 5v usb ports. The idea here is that you have a dedicated batt to run just the cpap. After all the cpap is the whole reason for the project. The other batt will run a second plug for something and the I can use the usb to charge my phone. I could have run the batts in parallel and had twice the capacity, but I didnt want to risk draining the batt on something else.
I figure I can get 20hrs (4 or 5 days sleep for me) out of one batt using the cpap. That is a guess using a calculator that tried to determine how long a LiIon batt would last at my pressure. Im sure you have seen it if you have looked at the batt backups. The batt they sell has fewer AH.
The whole thing runs in the box with the lid shut. The hose fits out the box vent perfectly. I am going to add switches for each batt so I can guarantee that the power is off. That will allow me to kill the cpap without opening the box too.
Sorry for the quick and dirty write up, I am in a hurry. Just wanted to throw it out there for your consideration.
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