[Equipment] ResMed Airsense 11 battery backup

[Bruce Lee]

Given the identical wattage and plug type, and despite seeing suppliers and Resmed saying it is not compatible, I took a chance and ordered the "AirMini DC/DC Converter 65W" to use with my Airsense 11.  It arrived today.

I can now CONFIRM that the Airsense 11 works fine powered from the AirMini DC/DC converter.

Plugged one end into my home-brew 12V AGM deep cycle battery / UPS system and the other end into the A11.  It powered up just fine.  I started it up (with humidifier and heated tube both ON), and it ran just fine (pressure set at 9).  I switched to "mask test" to test higher pressure, and again no problems.  This was all as expected, and given that the voltage/wattage is the same as the standard A11 AC/DC block, I expect the AirMini DC/DC adapter will support the A11's full range of pressure/humidity/tubing options.

One last question I had was what "minimum input voltage" the converter requires.  That isn't in the specifications; it just says "12V" which is typically used to describe a range from around 11.4 volts up to about 13.8 volts, or anything in between (the typical voltage range for lead-acid batteries and their charging systems).

According to the manual, the indicator LED has three states to indicate battery status.  I connected the adapter to a variable DC power supply and tested to establish the voltage thresholds for each state:

  >12.0v  ::  LED Green, "Normal Operation."  (I tested up to 13.8v, didn't go any higher.)
  <12.0v and >= 11.4v ::  LED Amber, "Low Battery" (but still operable)
  <11.4v  ::  LED Off, "Battery too low to operate machine."

So with the CPAP operating (i.e., battery under CPAP load), the voltage needs to stay above 11.4V or the adapter will shut down.

I’ve looked everywhere online for this info and find it here.. thank you so much for doing the legwork on this. Just recently received the AS11 and wanted a dc to dc adapter to use with my Jackery power station for off the grid camping. Will purchase the air mini adapter without worry. 

Much appreciated good sir!!!

[blhoward2]

Did you have to modify the AirMini DC plug at all? I see that the stock AirMini AC adapter is only shaved on one corner, while the Air Sense 11 cord is shaved on both.

[ScottZZZ]

Did you have to modify the AirMini DC plug at all?

No modification is required to use the AirMini DC/DC adapter with the Airsense11.  

The corner shaving of plugs and sockets is such that:

• The AirSense11 AC adapter can be connected to either the AirMini or the Airsense11.
  
• The AirMini DC/DC adapter can be connected to either the AirMini or the Airsense11.
  
• The AirMini AC adapter can only be connected to the AirMini (the plug/socket design prevents connecting it to the AirSense11). 
  

The AirMini AC adapter has insufficient wattage to power the AirSense11 -- and Resmed's plug/socket design (corner shaving) correctly prevents it from being connected to the AirSense11.

[Woodman17086]

I’ve attached a screenshot of what I found for a battery backup.  It uses a battery and an inverter that you plug your machine into.  Not cheap by any means but it would work.  Looks to me like it would work to hook the inverter into a 12 volt battery plug on a car or camper (Which is where I use the battery the most). Hope this is of help.

   

[Crimson Nape]

Having bought all the parts myself to run either an S9 or A10, the seller really likes his product a lot! I think I came out with a 175.00 price tag on all equipment for both models. Seeing that the DC-DC power supply for your model is $110USD on Amazon, your setup may run a little more. Anyway, using an inverter will eat up a bunch of battery power just to use it.

The bottom line is, if you feel like that it is a fair price for you, then go for it.

[ScottZZZ]

Having bought all the parts myself... the seller really likes his product a lot! .

That was my initial thought as well!  If using an inverter and standard A11 AC/DC supply, those are all the "right type of components" to utilize a 12V battery as the source -- but without knowing the brands or specifications, I would be hesitant to buy that particular package of parts.

As for the inverter efficiency loss...  Hard to avoid some loss with the A11.  Known choices with 12V source are an inverter (12V DC to AC, then using the standard A11 AC/DC supply), *or* the Resmed DC/DC converter (12V DC to 24V DC).  Both of those have significant losses.   

Using a 24V source (i.e., two AGM's in series) with the Resmed DC/DC converter is likely much more efficient, since it doesn't need to step-up the voltage, but I haven't seen any test data on that yet.  And then you either need a 24V charger or need to charge each 12V battery separately from a 12V charger.

A 24V source and a custom straight cord into the AS11 would eliminate all the losses.  But I haven't seen a determination of the exact AS11 connector pinout (as I recall, some Resmed models needed two different voltages on the plug).   Also, I have seen no testing of the AS11 with lower-than-spec input voltage, so it's unknown whether it will just shut down gracefully when the input falls below some voltage or if it might malfunction in some way.  (The Resmed DC/DC converter has a low-voltage cutoff on the input side, as do all the inverters I have used, so this is only a concern if trying to power the AS11 directly from a 24V battery source without a converter or inverter.)

[mug3n]

Sorry to jump in on this discussion here.  I recently ordered an Airsense 11 Autoset, and I also have an existing Freedom CPAP Battery v1 that I use for my Airsense 10, here: https://batterypowersolutions.net/produc...continued/.

My understanding from reading this thread was that the AS11 uses the same connectors as the Airmini (makes sense, given the mini and AS11 have the same bits inside at least motor wise).  So can I use a kit like this one: [DME Link Removed]Search cpapdirect for "resmed airmini 24v power converter for freedom battery"  to power my AS11 with the v1 battery?  I would very much like to avoid buying a new battery if possible.  Thanks!

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[Aldebaran]

   
If the plug is shaped like the one on top (see attachment), it will only fit into the AirMini. If the plug is shaped like the one below (in the attachment) it will fit in both the AirMini and AirSense 11.

Just an FYI, those two adapters were marketed for the AirMini. One is an 120V AC - 24V DC, the other is a 12V DC - 24V DC. But why the differently shaped plugs, you ask? Think of the receptacles on the devices itself and think of which of these two plugs will fit into them.

From what I could tell the "resmed airmini 24v power converter for freedom battery" looks like it wouldn't fit the AS11. It looks like the plug on top, in my attachment. If it were made of plastic, you might still be able to shave a bit off the corner with a file and make it work. But upon closer inspection, the plug is metal.

[ScottZZZ]

From what I could tell the "resmed airmini 24v power converter for freedom battery" looks like it wouldn't fit the AS11. It looks like the plug on top, in my attachment. If it were made of plastic, you might still be able to shave a bit off the corner with a file and make it work. But upon closer inspection, the plug is metal.

I cannot confirm which plug is shipped with the "freedom battery for AirMini".  It could, indeed, be the "low wattage plug" (one corner chamfered) which only fits the AirMini.

But the manufacturer (Battery Power Solutions) does claim to now have a kit specifically for the Airsense11.  So presumably that kit will ship with the "high wattage plug" (both corners chamfered) which will fit both the AirMini and Airsense11.

So, to echo your thought, anyone ordering a Freedom battery kit to use with their Airsense 11 should make sure the kit has the "high wattage plug" with both corners chamfered.

[mug3n]

Thanks much to you both, I'll investigate further.