Airsense 10 battery adapter wiring diagram

Hi -

I've used a CPAP & then a BiPap since 1995. Up until I got my Airsense 10 a few months ago they've always used a 12v power supply although the end on the cord is unique to the machine (i.e., can't use a laptop power supply). My Airsense 10 with heated humidifier is the only 24v machine I've had and I'd like to create a cable so I can use (2) 12v AGM batteries in my new travel trailer. The travel battery packages are ridiculous - over $300 - and a 12v to 24v cigarette lighter adapter is nearly $100.

Has anyone else dealt with this? On the low voltage side of the OEM adapter there are three wires - white, black & an uninsulated wire. It's pretty much impossible to measure the voltage on the tiny little center probe but there has to be some way of determining how the 24v is supplied. With a 2-wire plug I'd just wire two 12v batteries in series to get the 24v but with 3 wires apparently 2 of them are providing 12v each & the other is neutral.

Anyone else dealt with this?

Use a power inverter unless you want to go off grid. I just read yesterday that the center pin has to have 3vDc, but do not take my word for it. I have not tested this and the ResMed machine will only run if the voltage is very close to its tolerance. I think they are being a bit naughty by putting a plug like that on the end of the power supply, 1 - you can't buy one. 2 - very close tolerances make the machine stop if not right. I don't know why they chose 24vDC but it is very annoying. I had the choice of three machines, and I chose the Airsense10Autoset not thinking about the voltage. Now I want to go off grid and I have the same problem. It would not be hard to build a power supply, even if it has a strange plug, but then how do you get a plug to fit it. A 12vDC to 24vDC power supply is not hard to build, but they have added in the strange power connector just to foil us and make us buy their overpriced 12vDC to 24vDC adapter. The machine is very good, why did they spoil things by making it 24vDC? If anyone finds an answer, please let me know as I for one am not willing to pay the price for one in the UK. £110 is just for to much. Time the Chinese reverse engineered them :-)

I have the same issue i take breaks in my caravan where we are always off grid with a huge battery and solar pv , i am currently building a dedicated psu for the 24v machine ,the plug has three components though it looks like a standard coaxial power plug it has ground on the outer +24v on the inside wall and 3.2 volts on the pin in the center.incidentally our local hospital whom supplied the machine was informed we had accidentally left our power supply in Greece on a recent holiday so they happily supplied a replacement to which i scavenged the necessary plug from !. i have got a 10 amp 12 volt dc to 24 volt inverter and built a small circuit to make the 3.2 volt output so now i have a complete power supply built on the bench however i have not yet tested it over any amount of serious service time as i am still waiting for one part to arrive to complete the build ,if this one works satisfactorily i will have to build another one as both me and my wife have the same complaint and purchasing a battery pack is beyond our means.