How to run a ResMed AirMini on a USB power bank
Posted: Thu Jan 24, 2019 10:21 pm
Hello all, I am new to CPAPTalk here, but wanted to share an interesting project that I have recently completed.
I built a cable to power my ResMed Air Mini from a USB power bank. The solution works great and is approximately 80% less expensive than purpose built solutions out there such as the very expensive Medistrom pack. I will give the requisite warning that you probably shouldn't go down this road if your sleep therapy is a life-and-death matter, but for me it is a thing that stops my snoring and helps me (and my wife) get a better night's sleep. And I'll be darned if I'm gonna pay 400 bucks just so I won't saw logs on the airplane!
So here we go. You need:
1) A battery bank supporting USB C with PD (Power delivery) that can supply 20V up to 30W or more. I use the Anker PowerCore+ 26800 PD which was well recommended and was on sale when I bought it. There are a variety of brands at this capacity ranging from about $60-120. 26800mAh works out to roughly 100Wh which is the TSA limit for a battery pack taken on an airplane.
2) A 20V USB PD Trigger cable. This device negotiates with a USB supply to tell it what voltage to output and then passes that through. This one https://www.amazon.com/dp/B07G1V1MXP is pre-set for 20V and works great out of the box.
3) A switching boost converter capable of 1A sustained load. A good choice is the XL6009 which is a 4A capable device but stays cool at the current levels requires for the AirMini. Here is one supplier: https://amazon.com/dp/B00LP2LZ4M/
4) A cable to plug into the AirMini. The thing uses a proprietary connector and for the life of me I searched for a compatible part but came up short. I haven't found a less expensive source than the $29 replacement cable for the aforementioned Medistrom Pilot-24. https://www.respshop.com/cpap-supplies/ ... -1218.html
The construction is pretty simple, cut the DC barrel jacks off of the USB trigger cable and the AirMini adapter cable, then solder them to the input and output of the XL6009 boost converter respectively, red to positive, black to negative. Check the output with a voltmeter and adjust the screw on the regulator until the output reads 24V. You can put a piece of heat shrink around the module to protect it or if you know someone with a 3d printer there are little cases for it on Thingiverse that can be made up easily.
I have monitored the power consumption through a USB power meter. With a good seal the unit draws a fairly nominal amount of power. I set my machine for 10 cm H2O static with now EPR just to get a nominal consumption number. The unit consumes approximately 200mW during exhale and approximately 15W when inhaling quickly. Over a 10 minute test I measured approximately 150mAh of power consumed, making the consumption approximately 1000mAh per hour. This means that for me the power bank could be expected to run the machine for over 24 hours. I probably wouldn't push it that hard, but I have run it overnight a few times no problem with my phone also plugged in.
All in all I think it's a pretty nice solution. I would be interested to know everyone's thoughts.
I built a cable to power my ResMed Air Mini from a USB power bank. The solution works great and is approximately 80% less expensive than purpose built solutions out there such as the very expensive Medistrom pack. I will give the requisite warning that you probably shouldn't go down this road if your sleep therapy is a life-and-death matter, but for me it is a thing that stops my snoring and helps me (and my wife) get a better night's sleep. And I'll be darned if I'm gonna pay 400 bucks just so I won't saw logs on the airplane!
So here we go. You need:
1) A battery bank supporting USB C with PD (Power delivery) that can supply 20V up to 30W or more. I use the Anker PowerCore+ 26800 PD which was well recommended and was on sale when I bought it. There are a variety of brands at this capacity ranging from about $60-120. 26800mAh works out to roughly 100Wh which is the TSA limit for a battery pack taken on an airplane.
2) A 20V USB PD Trigger cable. This device negotiates with a USB supply to tell it what voltage to output and then passes that through. This one https://www.amazon.com/dp/B07G1V1MXP is pre-set for 20V and works great out of the box.
3) A switching boost converter capable of 1A sustained load. A good choice is the XL6009 which is a 4A capable device but stays cool at the current levels requires for the AirMini. Here is one supplier: https://amazon.com/dp/B00LP2LZ4M/
4) A cable to plug into the AirMini. The thing uses a proprietary connector and for the life of me I searched for a compatible part but came up short. I haven't found a less expensive source than the $29 replacement cable for the aforementioned Medistrom Pilot-24. https://www.respshop.com/cpap-supplies/ ... -1218.html
The construction is pretty simple, cut the DC barrel jacks off of the USB trigger cable and the AirMini adapter cable, then solder them to the input and output of the XL6009 boost converter respectively, red to positive, black to negative. Check the output with a voltmeter and adjust the screw on the regulator until the output reads 24V. You can put a piece of heat shrink around the module to protect it or if you know someone with a 3d printer there are little cases for it on Thingiverse that can be made up easily.
I have monitored the power consumption through a USB power meter. With a good seal the unit draws a fairly nominal amount of power. I set my machine for 10 cm H2O static with now EPR just to get a nominal consumption number. The unit consumes approximately 200mW during exhale and approximately 15W when inhaling quickly. Over a 10 minute test I measured approximately 150mAh of power consumed, making the consumption approximately 1000mAh per hour. This means that for me the power bank could be expected to run the machine for over 24 hours. I probably wouldn't push it that hard, but I have run it overnight a few times no problem with my phone also plugged in.
All in all I think it's a pretty nice solution. I would be interested to know everyone's thoughts.
