I just got a Shargeek Storm 2 battery charger (https://www.shargeek.com/products/storm2) to use for work. It's primarily used for recharging just about anything with a battery - phones, hot spots, laptops, cameras, etc. For such a tiny form factor the thing carries a lot of power, reportedly 25,600 mAh (25.6 amp hours) or 93.5 watt hours. It'll charge your phone six or seven times or a Macbook Pro once. That's a lot juice for a portable device, but it's under the FAA maximum and is safe and legal on airplanes. I found it at Amazon for $229 - https://www.amazon.com/gp/product/B09NY ... UTF8&psc=1.
The Shargeek has a fantastic LCD display with tons of information on it, just the thing for electricity geeks. It's also in a transparent case, which does absolutely nothing except make it attractive to people like me.
![Image](https://lozuk.com/pics/i.php?/upload/2022/09/19/20220919182630-3a0f035c-la.jpg)
It's tiny, but solid at just over a pound. The weight isn't insignificant in a backpack, but it's not terrible either. It has USB inputs and outputs for just about anything you want to charge.
![Image](https://lozuk.com/pics/i.php?/upload/2022/09/19/20220919182048-ced05824-la.jpg)
What caught my eye is its DC output, which is configurable from 12 to 24 volts through a DC5525 port. That's right in the sweet spot of what the Resmed DC-DC converter wants to power the Airsense 10 line, including my AirCurve VAuto. Theoretically, given its watt hour rating this tiny battery pack could power my CPAP for over 8 hours over the pressure range I use, which is 14-ish to 17-ish.
After a quick search on Amazon for a DC5525-to-5521 adapter and a DC5521 accessory outlet (i.e., an automotive cigarette lighter-style plug) I made one of these:
![Image](https://lozuk.com/pics/i.php?/upload/2022/09/19/20220919150932-b8a478ec-la.jpg)
I plugged the new Amazon cable into the Shargeek, plugged the Resmed DC-DC converter into the Amazon cable, turned it all on, and the Resmed powered up! It was very exciting until I took a couple of breaths, then the VAuto powered off hard. At that point I was already writing the experiment off, but then I noticed that just before the CPAP cratered, the display on the Shargeek showed that it was trying to pull 16 volts. Using the menus on the Shargeek, I changed the DC output from 12 volts, which is the default, to 18 volts and gave it another shot. Sure enough, now I could breathe continuously and the VAuto stayed on.
The next step was to try it out in actual battle. Time for a nap. The VAuto used 15 percent of the Shargeek's battery in 80 minutes of use. A little math shows that the Shargeek Storm 2 will power my VAuto for over 8.5 hours, which is plenty for my purposes. It will provide enough power for a whole night or certainly an airplane ride. The Shargeek is designed for deep-cycle discharges, which means you can take it down to 0% charge repeatedly without damaging it. This might be the battery I've been looking for.
Here's what it looks like powering the CPAP:
https://www.youtube.com/watch?v=Ys0_X167fx0