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Excellent Andy - I'm wondering if you were able to charge after the first nite then again after the 2nd how much time that would have taken? Surely it would be easier on the battery but another good option for using battery power.

To keep the conversation alive... here are some of my results from trying out a number of battery packs.

Initial conclusions: battery packs under 20000 mAh are not useful. A 20000 mAh battery might deliver 2 nights, 30000 mAh maybe 3-4 nights, 70000 mAh battery can deliver 8-9 nights. I use 20-25 Watt hours each night at 7-8.5 CM pressure on a Z2 APAP.

I used a JacobParts 15V USB-C PD trigger cable for most of the tests as the Z2 is supposed to run on 15 volts. This means when you're looking at battery specs you need to ensure it is capable of USB-C PD at 15 volts. Usually this means at least a 45 watt power capability (a "laptop" charger, not a "phone" charger). You will see something like this in the online specifications: "Type-c Output: 5V-3A / 9V-3A / 12V-3A / 15V-3A / 20V-3.25A (65W Max)". The part that says "15V" is important. If there's nothing like this, chances are that the battery you're looking at will not work with the Z2.




Most relevant columns are Advert mAh: the advertised size of the battery. Tested Wh: the power I was actually able to get from the battery at 15V PD. Tested sleep hours: how many hours of sleep I got before the battery was empty.

It's kind of geeky. I'll clean it up when I decide what information is actually useful for shopping. I have a couple more I want to try out but thought I'd post my progress to date. Lots of camping, not much hacking going on here so this project has ground to a halt for now.

Renogy GP-14:
https://www.amazon.com/gp/product/B0791WDZTW
Baseus:
https://www.amazon.com/30000mah-Baseus- ... B08JV4W4NY
Nitecore:
https://www.nitecorestore.com/Nitecore- ... b20000.htm
Ravpower:
https://www.ravpower.com/products/rp-pb ... power-bank
Qbrand:
https://www.amazon.com/dp/B09MLKF78N
Henhot:
https://www.amazon.com/gp/product/B09QRRGR9J

I just noticed the broken link to the RavPower 30000 mAh 90 watt laptop charger. Maybe they don't make it any more; I can't find it on Amazon either. It is identical to the Henhot unit so buy that (except the Henhot did not perform as well as the Ravpower in my tests). I found one on Newegg.com for $70.
https://www.newegg.com/black-ravpower-r ... -_-Product

Glacierjay thanks for posting all that info. That will help a lot of people.

My two week trip off grid didn't go as planned. I normally don't drive anywhere once I get camp set up but I had to drive a couple times and my trip was cut short and was only able to stay a week. I had bought two Baseus banks and the large Renogy. All I used for the week was one Baseus 30000 bank. I ran it on apap 8-10cm. Pretty certain it didn't ramp up the pressure so basically it was running at 8cm. The two drives I did where around 30-45 minutes each. I didn't monitor the charge but looked a the charge percentage on the battery bank. Each drive seamed to charge the bank enough that I would gain and extra night or two in that time. I slept for seven nights and think there may have been one night left in the bank. Since I didn't measure anything my guess is that I was able to recharge the bank with 1.5hrs of driving. That is a guess since I wasn't really keeping track. My Baseus cigarette lighter charger was charging the Baseus bank at around 69watts when I was driving. That's more than I've seen idling in the driveway. That's a pretty quick charge. Makes me think of getting a bank that charges at 100watts. With a short drive you can replenish a battery bank. Something to consider for the future.

It was great to leave the 100lbs of deep cycle agm batteries at home. So glad I switched to the Z2 and lithium. Time will tell if they remain reliable and trouble free. I have enough battery banks to easily last a couple weeks and with a little driving I can extend that significantly. I guess I'm skipping the solar for now but will keep researching. My hope is to do some kayak camping in the coming years. Still need to figure out if it's worth solar charging or just carrying all the batteries I'll need. I can carry more weight in the kayak vs backpacking.

I did monitor the temps inside my sit on top kayak. I wanted to see if it would be safe to store or possibly charge batteries inside the kayak. Water temps ranged from 61F to 76F on Lake Michigan, mostly upper 60's and low 70's. I monitored temps inside on sunny days that were in the 70's. I never really let the kayak sit on shore with the hatch closed so I suspect the temps would have climbed a bit. Also air temps were not real hot. When it was parked on shore I left the hatch open after getting out my lunch and drinks. The temps inside the kayak never got higher than the 80's. That's well within safe storage and charging parameters for lithium.

How about a solar panel on top of your car, constantly charging a leisure battery all day? Wouldn't that be enough to run your cpap every night?

Moojooles wrote: ↑

Tue Jul 05, 2022 4:38 am

How about a solar panel on top of your car, constantly charging a leisure battery all day? Wouldn't that be enough to run your cpap every night?

Car roof solar panels are just now becoming a thing.

Conventional solar panels can be too heavy, tricky to install and completely screw up the cars aerodynamics. Depending on location their mounting angle doesn't them to take much advantage of the sun.

A solar panel on top of a car roof wouldn't last very long. road hazard could destroy it. todays world somebody could walk off with it. what I would do. keep a 100 amp battery in the trunk, transfer watts from the bigger battery to the small battery with a battery inverter. use a DC to DC charger to keep the trunk battery topped off.

First time poster.
So, I purchased a Resmed DC/DC converter for my Airmini,

and the Renology 72000mAhr battery pack.
https://www.amazon.com/dp/B0791WDZTW?ps ... ct_details

This is probably old ground, but it appears as though the combo isn't going to get me 2 full 8hr nights of service.

What I think is happening is the DC/DC convertor is pulling a good deal of power in the conversion process, and the Airmini is going to shutdown earlier than expected because of the voltage dropping over time.

I'm going to try creating my own power conversion device, using a very simple buck/boost convertor
https://www.amazon.com/gp/product/B0B3F ... UTF8&psc=1

That allows a wide range of voltage input, to supply the 24VDC output, and a power cord that is apparently the same that used on the AirSense 11.
https://www.amazon.com/gp/product/B0B3F ... UTF8&psc=1

I'm sure we have some experimenters on the forums here. I'd love to hear from someone who has "been there, done that". I will be happy to post results.

Before this idea is dismissed, look at the convertor and the protections that can be configured.

stfcpap wrote: ↑

Fri Jul 15, 2022 2:54 pm

First time poster.
So, I purchased a Resmed DC/DC converter for my Airmini
and the Renology 72000mAhr battery pack.

This thread is dedicated to running the Airmini on a power bank. These are the folks to talk to since they have already been through what you are trying to do.
viewtopic/t174496/How-to-run-a-ResMed-A ... -bank.html

The Resmed DC converter may not be very efficient. Glacierjay also had the same problem with his Breas Z2 Apap. He only got 2.5 nights from the Renogy 72000 when using the 12vdc cigarette socket and the dc converter for that machine. I'd look at getting a 20v trigger cable that plugs into the usb-c output on the Renogy, connect that to a converter to go from 20vdc to 24vdc, then to your Resmed cable and machine. I think your on the right track. Ask the same question on that other thread and you should get some answers dedicated to exactly what you are doing.

Edit: Scratch that idea. I just realized the Renogy can output 24vdc from the dc output jack. You need to program the device, read the manual. All you should need is your adapter cable to go from the Renogy to your Airmini if the cable you bought has the right size plug. The manual says it can do 24vdc@2amps so 48watt max output from that jack at the needed voltage. Figure out if 48w is enough to power the Airmini at your pressure and try that jack first before going the usb-c route.

Edit: Air mini user manual says typical power consumption is 6.3watts or 27w max. So the dc jack on the Renogy at 48watts output is more than enough. All you'll need to do is figure out if the plug on your cable fits the Renogy jack and set the output to 24v. Before building a converter I would see how many nights you can get using the small dc jack. I read the jack size is 5.5mm x 2.5mm . My cable plug is 5.5mm x 2.1mm and seems to work just fine. Not exactly sure on the size.

Rob K
I appreciate your response, and for the reference to the other thread. I have just started my information and experience journey.
I did plan to investigate running the AirMini directly from the battery pack using the DC OUT connector, where the DC OUT voltage can be set using a selector pushbutton on the battery pack.

Something I suspect however, is that the rating for the 72000maH may be optimistic / ideal and something that is not "sustained" over time and in addition, a rating for the individual cells in the device which are 3.7V each. One reviewer of the battery pack on Amazon indicated that for 24V output, the rating should be divided by 6 (72/6=12Whr). The converter I purchased has the advantage that it will handle a wide range of input voltages to create the output of 24V. So then, even if the converter results in some loss during the boost process, theoretically it can handle the discharge of the battery to a much greater extent than simply running the 24V until it drops below a threshold that causes the CPAP to shutdown. I really want to have the under-voltage / over-voltage and under-current protections provided by the buck/boost module so that the AirMini is not otherwise electrically stressed.

Thanks again!

Just a quick check-in. I am on schedule for a 13-night backpacking trip around Mount Rainier on the Wonderland trail next week. I've only managed to do one 3-day backpack trip this summer and a bunch of overnight trips and car camp trips. As a result I don't have a lot to add yet: batteries are performing about as I said in my tests or a little better. When I get back in mid August I'll report on how it all goes.

There are a couple of places along the Wonderland trail to cache food, and I will also cache batteries. I never have to carry more than 5 nights' capacity so that changes my strategy. I will not be using the Renogy GP-14 that we have discussed so much in this string. While it can provide 8+ nights of therapy it weighs more than two 3-night batteries.
First segment is 3 nights. I will carry the delightful Nitecore NB-2000 battery (11.4 oz) on that segment. I got 2.5 nights from that battery on several occasions. I will limit sleep time to 6 hours.
Next segment is 5 nights. I will carry the Baseus (1.2 lb) and Ravpower (1.2 lb) batteries, collecting them from the cache along with my food.
Last segment is 5 nights. I will carry Henhot (1.18 lb) and Qbrand (1.69 lb) batteries.

Every time I pick up batteries I will leave behind the depleted batteries so I don't have to carry them. I will go back to the cache points after the trip to pick them up. As a result I am carrying about 3 lbs of CPAP gear. Not bad!

My setup for nights 1-3 (weight 1 lb 15 oz):
Breas Z2 cpap: https://breas.us/products/cpaps-for-travel/z2-auto/
Travel hose: https://www.amazon.com/gp/product/B01B5DHJ5O
Power cable: https://www.amazon.com/gp/product/B08NS491XW
Mask: Resmed N30i https://www.cpap.com/productpage/resmed ... -cpap-mask
Battery: https://www.nitecorestore.com/Nitecore- ... b20000.htm

- Jay

wow!

this sounds amazing!

Rob K wrote: ↑

Fri Jul 15, 2022 7:07 pm

Edit: Air mini user manual says typical power consumption is 6.3watts or 27w max. So the dc jack on the Renogy at 48watts output is more than enough. All you'll need to do is figure out if the plug on your cable fits the Renogy jack and set the output to 24v. Before building a converter I would see how many nights you can get using the small dc jack. I read the jack size is 5.5mm x 2.5mm . My cable plug is 5.5mm x 2.1mm and seems to work just fine. Not exactly sure on the size.

Rob, I determined that the Renogy has a built-in DC-DC "boost" converter. It would have to because none of the cells in that pack are anywhere near 24VDC. I was going to test the battery with the AirMini, but at 1yr, my AirMini has decided to go on the blink. Anyway, yes, by pressing the button on the right of the power pack, one can set the target output voltage of the device. And yes, if it already has a built-in boost converter, no sense using another at the same time.

So I used the battery pack with my AirSense10 and with a DC-DC converter made by TAIFU (much less expensive than ResMed's) as I was in a hurry:
https://www.amazon.com/dp/B07VV231SJ?ps ... ct_details

and for one night anyway, the combination worked very well. The Airsense10 uses a special 3terminal plug with a sensing circuit to know it's connected to a compatible supply. Pretty sure I know how to hack a cable to output the proper sensing voltage based on someone's YouTube video so I could bypass the TAIFU converter... I'm on that slippery slope of supply equipment. Grrrr.

Thinking of returning, or otherwise selling the ResMed converter for the AirMini now that my unit is in the shop.

I wish I had an answer for you but I don't. The manual and online information on the Renogy GP14 is extremely vague. I don't know what sort of safety protections it provides. I would contact Renogy and ask.

Lithium cells are usually around 3.7vdc give or take. If you wire them in series you can get any multiple of the single cell voltage. This is a generalization but seven cells in series would be around 25.9vdc. I have no clue of how they configured the circuitry. I suspect they wouldn't provide a schematic or any of the manufacturing details unless you were authorized to receive service and repair information.

I’ve been using the Maxoak battery (non FAA) for the past 2 years with my Resmed Airsense 10. I run 4-10 cm and average about 7. I’ve found that setting the humidifier to 1 and tube temp to the low 60s sets me for a comfortable night of sleep here at high altitude locations in Colorado and the West. I usually sleep 6-6.5 hours a night. I can get 3 nights just about guaranteed out of this setup and possibly 4. I think the machine has to work less at higher altitude. The nice thing about the Maxoak of course is that it’s made to output 4 amps at 24v. For anything like a Jackery or Ecoflow you will need an adapting cable. I just bought the Ecoflow River with extra battery mainly to run a fridge, but it could be put into CPAP duty if necessary. These kind of batteries are easier to charge off a 12v car outlet.

Looks like I’m going to take advantage of the Direct Home Medical sale and finally buy an Airmini. I’m guessing it could go a week or longer on these larger batteries. I know there’s some very small batteries that are very expensive and meant to be used with the Airmini. I would eventually like to use this on a kayak.

Richdksu wrote: ↑

Sun Aug 07, 2022 5:30 pm

I’ve been using the Maxoak battery (non FAA) for the past 2 years with my Resmed Airsense 10. I run 4-10 cm and average about 7. I’ve found that setting the humidifier to 1 and tube temp to the low 60s sets me for a comfortable night of sleep here at high altitude locations in Colorado and the West. I usually sleep 6-6.5 hours a night. I can get 3 nights just about guaranteed out of this setup and possibly 4. I think the machine has to work less at higher altitude. The nice thing about the Maxoak of course is that it’s made to output 4 amps at 24v. For anything like a Jackery or Ecoflow you will need an adapting cable. I just bought the Ecoflow River with extra battery mainly to run a fridge, but it could be put into CPAP duty if necessary. These kind of batteries are easier to charge off a 12v car outlet.

Looks like I’m going to take advantage of the Direct Home Medical sale and finally buy an Airmini. I’m guessing it could go a week or longer on these larger batteries. I know there’s some very small batteries that are very expensive and meant to be used with the Airmini. I would eventually like to use this on a kayak.

I have been following somewhat but my eyes glaze over with electrical specs. I used to think I was techy but I would need very specific instructions so the precious machine doesn’t get crashed.

I want a backup for home use and solar recharge.
Also option to charge in the car while driving.

I am intrigued by scooter batteries or lithium iron phosphate type. I understand adapters would be necessary and am not super thrilled with the notion if the battery and two leads. I would love to find a case to tidy it up. I just don’t know how and what I need to get a similar 3-4 days of juice.

which Maxoak? please and thanks