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funvill / funvill.github.io

This repo is for the website blog.abluestar.com, based on the Minimal-Mistakes template for Jekyll
https://blog.abluestar.com
MIT License
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usb-c-pd-power-bank-to-resmed-airmini-or-airsense-cpap/ #28

Open utterances-bot opened 2 months ago

utterances-bot commented 2 months ago

USB-C PD Power Bank to Resmed AirMini or Airsense CPAP - A Blue Star

Is it cheaper to build your own solution to portable CPAP battery, or buy something off the shelf?

https://blog.abluestar.com/usb-c-pd-power-bank-to-resmed-airmini-or-airsense-cpap/

caquino commented 2 months ago

Hey, just started my CPAP therapy 20 days ago and was looking for a solution using USB-C PD, thanks for sharing this! Are you still using this solution? how have it been working for you?

I've already configured an raspberry pi 0 with an ez share sd card with wifi to automatically send my CPAP data to google drive where I can import it later to OSCAR to review the sessions and it has been working really well, thinking about writting a blog post about it.

funvill commented 2 months ago

@caquino It lasts significantly less then 8 hours. Close to 6 hours. I think the DC-DC boost converter is much less efficient then advertised, or my math is wrong.

I used this setup for about 22 days with success. 6 hours instead of 8 hours was a little annoying but I got use to it.

I've already configured an raspberry pi 0 with an ez share sd card with wifi to automatically send my CPAP data to google drive where I can import it later to OSCAR to review the sessions and it has been working really well, thinking about writing a blog post about it.

Always good to share the information with other ;)

protein-function commented 2 months ago

Will any DC-DC 24V boost converter work (can you put a link for an example DC-DC 24V boost converter). I would expect such a converter more efficient for 20V --> 24V than its more typical application of 12V to 24V, is this true? Does such a converter 'need to be told' what the input voltage is.... of does it merely take what it finds and brings it up to 24V?

protein-function commented 2 months ago

BTW, I am planning to use this USB-C cable converter on a large 12V power station (for camping & power outages) because I believe using the DC directly is more efficient than plugging an AC power brick to the power station via the DC to AC inverter.

funvill commented 2 months ago

@protein-function

I would expect such a converter more efficient for 20V --> 24V than its more typical application of 12V to 24V, is this true?

I am not sure. 12-24 is by far the most common (and cheapest), I already had one in my office so I used it.

If you have 20V you may not need to boost it to 24v. My 'Resmed AirMini' operated fine on 20v even though it said that it needed 24v. It wouldn't run on 18v though.

Does such a converter 'need to be told' what the input voltage is.... of does it merely take what it finds and brings it up to 24V?

The DC-DC boost converter will have its input voltage specified. I know there will be a minimum voltage required (10v) but I am not sure about the upper range

protein-function commented 2 months ago

@funvill

If you have 20V you may not need to boost it to 24v. My 'Resmed AirMini' operated fine on 20v even though it said that it needed 24v. It wouldn't run on 18v though.

This solution would look something like this: USB-C PD Power bank => 20V USB-C PD Trigger cable => DC-DC 24v boost converter => Barrel jack to Resmed proprietary plug => CPAP machine.

I believe you used DC-DC 24v boost converter. If Resmed Airmini 'operated fine' on 20V, was your use of DC-DC 24v boost converter actually optional. Did you use DC-DC 24v boost converter because you were more comfortable with delivering the specified 24V than 20V (without DC-DC 24v boost converter) which also seemed nominally workable.

funvill commented 2 months ago

@protein-function I started with the "DC-DC 24v boost converter" first because that is what the Resmed Airmini said that it required on the adapter/box. It worked great and I wrote the article.

I tried without the boost converter afterwards and it still worked fine. The Resmed Airmini must have a acceptable input range larger then what is written on the box. I also tried with 18v and it did not work.

protein-function commented 2 months ago

@funvill Ahh. I see. I was also wondering and hoping the Resmed Airmini might work with 20V. Thanks for the write-up and for all the back and forth clarification. I really like this approach and have learned a lot about USB-C etc. Also, FWIW, I'll probably give it a try/start without the 20V--> 24V adapter. Thank you!

protein-function commented 2 months ago

Regarding my earlier question about relative efficiency of stepping up from 12V vs 20V to 24V out. This graph shows that indeed it is less efficient to step up to 24V from lower voltage than higher voltage. https://a.pololu-files.com/picture/0J4912.1200.png?04ce60f96d7f85af2dce53a4a2d98f9b

adam479 commented 1 month ago

i ordered machine from this https://orderyoursupplies.com/products/airsense-11-autoset-cpap-with-humidair-climateline-tubing

is it compatible with this?