Do the trailer outlets run off the batteries?

The outlets that look like the outlets in a house are 120v. The trailer must be plugged into a 120v source for the 120v outlets to be active. Like an electrical pedestal at a RV park or in your driveway. For you to get 120v when not plugged in you can use an inverter. If you are not sure if the trailer already has one, it probably doesn't. The 120v outlets will not power a 12v device without a transformer of some type. A 12v outlet resembles a cigarette lighter outlet. About a 3/4 inch round hole. If you have one of those, you can use an inexpensive (around 50 bucks or less) low power inverter that just plugs in to the lighter socket. If you do not already have a 12v socket close to where you need your CPAP, it would cost you less than 100 bucks to have one installed. Much cheaper if you can do it yourself. Walmart and many other stores sell everything you need and may even offer installation through their automotive department. Same folks who would install a new radio/stereo in a car anywhere could do this very quickly. I got my mom one of the low cost inverters for her nebulizer used for COPD. It plugged into the cars cigarette lighter. Also, check with the hospital or provider thst supplied the CPAP unit. They probably have everything you need. The place where we got ours, had the inverters for sale.