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[Equipment] ResMed Airsense 11 battery backup
#21
RE: ResMed Airsense 11 battery backup
Same boat - my son is in scouts & I need battery power to run the unit through the night.

Drives me crazy... Going DC-AC-DC just drains the portable battery.
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#22
RE: ResMed Airsense 11 battery backup
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.
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#23
RE: ResMed Airsense 11 battery backup
This is fantastic news! Thank you!
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#24
RE: ResMed Airsense 11 battery backup
It's probably worth checking how hot the cable and/or the adapter gets while being used at high power. Drawing more power than a device is designed to provide won't necessarily instantly kill something, but if the parts and cables aren't rated for that amount of power there is the potential for parts to burn out with extended usage. This could be as simple as a part or component letting the "magic smoke" escape, or it could be a fire hazard, depending on the circumstances.

- Neelix
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#25
RE: ResMed Airsense 11 battery backup
(11-01-2021, 07:19 PM)Neelix Wrote: It's probably worth checking how hot  the cable and/or the adapter gets while being used at high power.   Drawing more power than a device is designed to provide won't necessarily instantly kill something,   but if the parts and cables aren't rated for that amount of power there is the potential for parts to burn out with extended usage.   This could be as simple as a part or component letting the "magic smoke" escape, or it could be a fire hazard, depending on the circumstances.

- Neelix

Wrong…. It is NOT drawing more power than designed!!!

The AirMini dc/dc converter is designed for 65 watts at 24v.  That is EXACTLY the same as the AC/DC adapter provided with the AS11.

It is really obvious, based on ratings and the plug designs, that Resmed designed the DC/DC adapter to be compatible with both the AirMini and the AS11. Marketing and packaging just hasn’t caught up with engineering.
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#26
RE: ResMed Airsense 11 battery backup
And yet I've encountered a problem in the past where using a product within the stated design specifications of a power supply still resulted in a component of the power supply melting and releasing the magic smoke. If they are saying it shouldn't be used, I have to wonder if there is something they aren't saying about the internals... I'm not saying that you shouldn't use it, just that you should be wary and keep an eye on it for a while. Just because the two devices nominally use power supplies that are rated the same, doesn't mean they actually draw the same amount of power and prolonged usage of a power supply at a higher power level than the product the power supply was designed to power could have unplanned effects.

- Neelix
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#27
RE: ResMed Airsense 11 battery backup
(11-01-2021, 05:27 PM)ScottZZZ Wrote: 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.

Thanks ScottZZZ, this confirms that a battery backup/DC-DC solution exists for Airsense 11 machines, despite contrary information.
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#28
RE: ResMed Airsense 11 battery backup
This was really useful. It's kind of annoying that when I convert to an A11, I will have S9, A10, and A11 DC-DC converters that all cost $85.00.

I was suspicious that Resmed had some proprietary protocol they used between the machine and the power brick. I'd still like to see a real report of someone using this DC-DC power brick for an overnight test run.
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#29
RE: ResMed Airsense 11 battery backup
(11-02-2021, 07:16 AM)Neelix Wrote: And yet I've encountered a problem in the past where using a product within the stated  design specifications of a power supply still resulted in a component of the power supply melting and releasing the magic smoke.  If they are saying it shouldn't be used, I have to wonder if there is something they aren't saying about the internals... I'm not saying that you shouldn't use it,  just that you should be wary and keep an eye on it for a while.  Just because the two devices nominally use power supplies that are rated the same,  doesn't mean they actually draw the same amount of power and prolonged usage of a power supply at a higher power level than the product the power supply was designed to power could have unplanned effects.

- Neelix

Please stop trying to scare people with this nonsense.  We're talking about specific Resmed machines and power supplies here, not whatever device you mistakenly blew up sometime in the past.

It seems you've done zero research on these.  The power requirements for the two machines (AirMini and Airsense11) are not the same.  The AirMini ships with a 20W AC adapter, and the Airsense11 ships with a 65W adapter.  Their actual power consumption is less in both cases.  

I haven't seen anyone from Resmed or their authorized suppliers has said "you shouldn't use it."  What they've said is "it isn't compatible."  Those are first-level, public-facing employees hired to respond to customer inquiries, and all they're doing is quoting from the previously published marketing materials.  They aren't electrical engineers, and they haven't tested the equipment. 

Have you tested the machines' actual current consumption?  I have.  Outside of brief peaks at startup, the AirMini pulls around 10-14W, and the AirSense11 draws about 30-45W with heater and heated tube both active.  The AirMini is shipped with an AC/DC supply rated at 20W, and the Airsense11 with an AC/DC supply rated for 65W.  Not just "rated", but "approved" by multiple regulatory agencies around the globe.

We're talking about Resmed, who manufactures approved medical devices. When Resmed designs and tests a power supply rated for 65W, and completes the regulatory compliance approvals around the world (including UL where I live), I guarantee you that supply will safely handle a 65W load -- and in fact will safely handle quite a bit in excess of that. The AirMini DC/DC adapter's rated output of 65W is ENTIRELY CAPABLE of handling the AirSense11 current requirements.  It also has way, way more capacity than needed for the AirMini -- which is evidence it wasn't designed solely for the AirMini.

Resmed has historically been very careful with their plug designs, engineering them to physically prevent connection of an incorrect voltage/wattage supply.  The new, seemingly proprietary plugs used with the AirMini and Airsense11, all have the same internal connections.  The housings are slightly different (corner chamfers).  That design ingeniously allows the 20W adapter to connect to the AirMini, allows both 65W adapters to connect with either machine, but physically prevents the 20W adapter from connecting to the AirSense11.  I guarantee all that is not by accident, but rather deliberately engineered to enforce compatibility through physical connectivity restrictions.  

Oh, and lastly....   

I used the AirMini 65W DC/DC adapter, on battery power, connected to my Airsense11 for 9.4 hours last night.  AHI was 0.3.  Nothing caught on fire. Wink
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#30
RE: ResMed Airsense 11 battery backup
(11-02-2021, 11:45 AM)ScottZZZ Wrote: Resmed has historically been very careful with their plug designs, engineering them to physically prevent connection of an incorrect voltage/wattage supply.  The new, seemingly proprietary plugs used with the AirMini and Airsense11, all have the same internal connections.  The housings are slightly different (corner chamfers).  That design ingeniously allows both the 20W and 65W adapters to connect with both the AirMini or Airsense11, while physically preventing the 20W adapter from connecting to the AirSense11.  I guarantee you that is not by accident, but rather deliberately engineered to enforce compatibility through physical connectivity restrictions.  

Oh, and lastly....   

I used the AirMini 65W DC/DC adapter, on battery power, connected to my Airsense11 for 9.4 hours last night.  AHI was 0.3.  Nothing caught on fire. Wink

Slight correction Wink
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