Resmed Airsense 11 - AC/DC adapter?

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palerider
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Re: Resmed Airsense 11 - AC/DC adapter?

Post by palerider » Sun Oct 03, 2021 11:26 pm

SleepGeek wrote:
Sun Oct 03, 2021 6:22 pm
So that begs the question why all the other cpap manufacturers still use 12V for their cpaps?
<sigh> :roll: I doubt you can give a straight answer.

I think you think you work for re$med.
Because the Re$med motor has to be more responsive, (to allow it to do FOT) and using higher voltage allows smaller gauge windings while still delivering the required power.

Philp$ Re$pironic$ and Devilbi$$ don't have the technology, (but they do u$e more $ $ign$).

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Dog Slobber
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Re: Resmed Airsense 11 - AC/DC adapter?

Post by Dog Slobber » Tue Nov 02, 2021 10:42 am

cliffracer wrote:
Fri Sep 17, 2021 10:50 am
My question is, do you guys think that this Air Mini DC power adapter would work on the 11? I called Resmed and the guy I spoke to said it 'probably' would not be compatable. My concern is that the 11 is so new that their staff may not be able to confidently answer the question. If the power port and the wattage are the same, it stands to reason that it would work.
Bumping this topic to report that an individual on ApneaBoard has confirmed that the AirMini DC-DC converter works with the Air 11.

http://www.apneaboard.com/forums/Thread ... #pid419936
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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Re: Resmed Airsense 11 - AC/DC adapter?

Post by Scott_G » Tue Nov 02, 2021 5:39 pm

Dog Slobber wrote:
Tue Nov 02, 2021 10:42 am
Bumping this topic to report that an individual on ApneaBoard has confirmed that the AirMini DC-DC converter works with the Air 11.
And... A full 9.4 hour overnight usage test, from the same individual (me), with humidifier and heated hose active:
I used it last night for 9.4 hours. Worked perfectly.

To be specific... That's the "Resmed AirMini 65W DC/DC converter (p/n 388389)", powered by a fully charged 12V AGM battery, and connected to a Resmed AirSense11 Autoset with the humidifier and heated tube active (Climate "auto", tube 84F). Worked exactly as it does from the 65W AC/DC adapter all night long.

Regarding the humidifier and heated tube.... I'm using a large capacity (55Ah) battery, so I can get 2-3 nights WITH the humidifier and heated tube running. With smaller capacity batteries, turning off the humidifier and heated tube may be necessary to get a full night's usage.

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Re: Resmed Airsense 11 - AC/DC adapter?

Post by ChicagoGranny » Wed Nov 03, 2021 8:18 am

Scott_G wrote:
Tue Nov 02, 2021 5:39 pm
And... A full 9.4 hour overnight usage test, from the same individual (me), with humidifier and heated hose active:
Thank you, Scott!


And thanks to PR and BB for using actual technical information to poop on the parade of market-cynics/conspiracists.

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Re: Resmed Airsense 11 - AC/DC adapter?

Post by SleepGeek » Fri Nov 05, 2021 7:00 am

Scott_G wrote:
Tue Nov 02, 2021 5:39 pm

And... A full 9.4 hour overnight usage test, from the same individual (me), with humidifier and heated hose active:
I used it last night for 9.4 hours. Worked perfectly.

To be specific... That's the "Resmed AirMini 65W DC/DC converter (p/n 388389)", powered by a fully charged 12V AGM battery, and connected to a Resmed AirSense11 Autoset with the humidifier and heated tube active (Climate "auto", tube 84F). Worked exactly as it does from the 65W AC/DC adapter all night long.

Regarding the humidifier and heated tube.... I'm using a large capacity (55Ah) battery, so I can get 2-3 nights WITH the humidifier and heated tube running. With smaller capacity batteries, turning off the humidifier and heated tube may be necessary to get a full night's usage.
Super job Scott - for those who need this battery adapter better get one before the price doubles.

billbolton wrote:
Wed Sep 22, 2021 3:31 am
Without schematics for both devices (which are not publicly available) there is no way of knowing with any certainty.

AFAIK there is a significant size difference in the form-factor of the two power adapters, which strongly suggests to me that they are not likely to be interchangeable.
Why folks dont like it when you treat em the way they treat you?
If you can be anything why not choose to be kind?
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cliffracer
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Re: Resmed Airsense 11 - AC/DC adapter?

Post by cliffracer » Mon Jan 24, 2022 12:23 pm

Thanks for all the posts, everyone! I just bought one of these and will report back how it works for me as well so we have a couple of practical experiences documented. Weird thing, I saw a review or two on the amazon page that this did not work for people but there were also others that claimed it worked as well. I am more apt to take the opinions on this forum, though.

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Re: Resmed Airsense 11 - AC/DC adapter?

Post by zonker » Mon Jan 24, 2022 12:40 pm

cliffracer wrote:
Mon Jan 24, 2022 12:23 pm
Weird thing, I saw a review or two on the amazon page that this did not work for people but there were also others that claimed it worked as well.
yeah, i'm less than impressed with so called negative reviews on amazon. some of those reviewers wouldn't be satisfied with ANYthing they bought, no matter the source.
cliffracer wrote:
Mon Jan 24, 2022 12:23 pm
I am more apt to take the opinions on this forum, though.
well, let's not get carried away!
:lol: :lol: :lol:
life is good, with a circle of friends.

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Re: Resmed Airsense 11 - AC/DC adapter?

Post by Scott_G » Mon Jan 24, 2022 1:21 pm

I'll update this to say that the DC/DC converter is still working well in my setup, having been used every night since early November 2021. My main objective was as a long-running UPS to cover power outages, and indeed I have slept right through several power outages with no interruption at all. It's been too cold here for camping, but I look forward to using it there as well.

My main disappointment is the lack of efficiency. It isn't just a straight power cord, as was used with my previous 12V Respironics PR60. Rather, the Resmed DC/DC converter is a "boost" device that takes in 12V in and puts out the 24V needed by the AS11. That boost process incurs some efficiency loss, and that means the DC/DC converter is only slightly more efficient than the combination of an Inverter with the standard AS11 AC/DC converter.

I did some short efficiency tests at my pressure and flow, not comprehensive tests with multiple pressure/flows or heat settings, so consider these numbers APPROXIMATE: In my tests, the standard AC/DC converter in combination with a sine-wave inverter was about 64-70% efficient, while the DC/DC converter was about 72-78% efficient. Actual efficiency in a given setup will depend on several factors, including the quality of the inverter and the actual power draw at given pressure, flow, and humidity settings. But both methods waste a lot of power, mostly dissipated as heat from the DC/DC converter, or from the Inverter and AC/DC converter.

That does give the DC/DC converter an edge of perhaps 8%, and (depending on the situation) that might mean the difference between a partial and full night's sleep. But in terms of runtime from a given battery source, there isn't really a HUGE difference between using the DC/DC converter versus using an Inverter and standard AC/DC converter combination.

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Re: Resmed Airsense 11 - AC/DC adapter?

Post by cliffracer » Mon Jan 24, 2022 8:43 pm

Scott_G wrote:
Mon Jan 24, 2022 1:21 pm
My main disappointment is the lack of efficiency. It isn't just a straight power cord, as was used with my previous 12V Respironics PR60. Rather, the Resmed DC/DC converter is a "boost" device that takes in 12V in and puts out the 24V needed by the AS11. That boost process incurs some efficiency loss, and that means the DC/DC converter is only slightly more efficient than the combination of an Inverter with the standard AS11 AC/DC converter.
Well poo. That was something I was really hoping for was that efficiency bump that I read about from the DC adapter on the Airsense 10. Ahh well, at least it gives me the ability to use it with the cig lighter in the car. Thanks for sharing your experiences, Scott!

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Re: Resmed Airsense 11 - AC/DC adapter?

Post by SleepGeek » Mon Jan 24, 2022 8:56 pm

Yes very well written.

It's just too bad that resmed didn't do like the other vendors and simply use 12V - the resmed S8 was 12V iirc.
I think they just got greedy there.
Why folks dont like it when you treat em the way they treat you?
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Re: Resmed Airsense 11 - AC/DC adapter?

Post by chunkyfrog » Mon Jan 24, 2022 11:43 pm

No. You skipped over the part that says Resmed uses 24 volts because the
superior technology they use REQUIRES it.
My Devillbiss is inferior, but for temporary use it's OK.
My Airsense 10 Autoset provides the "finesse", etc. that I need now.
.

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Re: Resmed Airsense 11 - AC/DC adapter?

Post by SleepGeek » Tue Jan 25, 2022 6:37 am

chunkyfrog wrote:
Mon Jan 24, 2022 11:43 pm
No. You skipped over the part that says Resmed uses 24 volts because the
superior technology they use REQUIRES it.
Kindly share the link to "THAT PART".
TY
Why folks dont like it when you treat em the way they treat you?
If you can be anything why not choose to be kind?
we are here to help.
palerider aka GrumpyHere wrote: What exactly do you think you're adding to this thread?

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Re: Resmed Airsense 11 - AC/DC adapter?

Post by chunkyfrog » Tue Jan 25, 2022 10:24 am

palerider wrote:
Sun Oct 03, 2021 11:26 pm
. . .
Because the Re$med motor has to be more responsive, (to allow it to do FOT) and using higher voltage allows smaller gauge windings while still delivering the required power.
. . .
THIS
FOT--Not everybody can do it.
Or cares to.
Approximations done by others are much more noticeable, and disturb sleep.
True FOT is far superior.
So THERE!

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Re: Resmed Airsense 11 - AC/DC adapter?

Post by Scott_G » Tue Jan 25, 2022 10:48 am

Drifting a bit off topic here, but from an engineering perspective there can definitely be advantages with 24v. It allows smaller gauge wiring, and lower motor mass (smaller windings) that reduces inertia and allows faster response to RPM changes. That would certainly be a benefit in implementing forced oscillation technique (FOT, ref by @chunkyfrog) in a CPAP. I'm not a Resmed Engineer so I have no knowledge as to whether that is why Resmed chose 24v. But there are also some cost and size advantages to smaller/lighter 24v components and wiring.

It wouldn't be an issue if we all had 24v batteries laying around. The ubiquity of large capacity 12v batteries is the only reason we find 24v operation "inconvenient". I've given some thought to wiring two 12v AGMs in series, reverse-engineering the pinout voltages on the DC/DC adapter plug and wiring up a straight cord. I may do that the next time my 12v battery is due for replacement. :-)

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Re: Resmed Airsense 11 - AC/DC adapter?

Post by ChicagoGranny » Tue Jan 25, 2022 12:20 pm

Scott_G wrote:
Tue Jan 25, 2022 10:48 am
Drifting a bit off topic here, but from an engineering perspective there can definitely be advantages with 24v. ...
Thank you. I'm now a little less aggravated with ResMed when I have to use their converter. :wink: