Battery solution for Breas Z2 Auto and HDM Z1 CPAP offgrid (backpacking, camping) usage

2021 Update: I upgraded my offgrid cpap equipment. Please see latest posts on the thread for more details and links.

• Changed cpap machine from a Z1 to a Z2 Auto CPAP. Can switch between CPAP & APAP to optimize pressure. Support for bluetooth and nitelog app support to get AHI in the field.
• Changed to Nitecore NB20000 batteries. The carbon fiber case reduces the weight.
• Changed to a standard usb-c pd trigger to 15V dc cable from JacobsParts. No longer need to make a custom cable.

2020
I did search the cpaptalk site for similar posts however did not find posts based on recent technology developments. I did find mech18's related post on Z1 APAP custom setup for Kilimanjaro from 2018 using a boost module that was most useful. I also read the sticky "newbies please read before posting" post. Disclaimer: I am not a medical or electronic/electrical expert so use at your discretion. Caveat emptor. Please consider consulting your sleep doctor if adjusting your treatment.

Below is the background on my cpap battery exploration. Feel free to jump ahead to the "Parts and Build" section below.

Background
Since my 2015 sleep apnea diagnosis (ahi 32+) in 2015, I have been using a ResMed AirSense 10 AutoSet with ResMed AirFit P10 pillow mask for home usage (pressure 10cm). By choice I don’t use the humidifier option. For offgrid usage I have used two BPS C100 batteries with a 12V to 24V adapter to power the AirSense 10 for multi night car camping and backcountry yurt trips. Setup challenges:

• bulkiness, weight and recharging times. Was ok for car camping. Not suitable for backpacking due to weight.

Since 2017 I have been using a HDM Z1 with ResMed AirFit P10 pillow mask for travel and offgrid (backpacking, car camping, sailing, etc). I used the HDM Powershell with two 48Wh capacity batteries. On 10cm pressure I got about 6 ish hours from each 48Wh battery. Setup challenges:

• Recharge time: sometimes each battery could take 6+ hours to charge depending on capacity used overnight.
• Recharge and use cpap machine: While the z1 cpap machine is being used at night, unable to charge batteries. Likewise when charging unable to use cpap. I currently have one ac adapter and powershell so a workaround could be to purchase additional ac adapters and power shells to charge overnight and use Z1 cpap machine at the same time. However this could get complex and challenging quickly beyond 2 batteries. Related to this, last year on a two week sailing trip it was a challenge when coming into dock/anchorage for a single night to rush to recharge batteries and sleep. HDM did release an "Extended Life battery" with 99Wh capacity for $339. However the $ per Wh doesn’t make it that cost effective considering available alternatives. One would still need to manage multiple powershells and ac to dc power adapters.

With the above in mind, for the past 8+ months I have been searching for and refining a fairly simple, cost effective and best weight solution for a cpap battery system for my multi night offgrid usage. I have used it for 3+ and 7+ night backpacking trips, remote backcountry yurt 3+ night trips and as a backup when winter storms have taken out the local ac power.

To fine tune battery usage and still maintain effective treatment I have also been trying out lower pressure settings and reduced usage hours.

• I can just barely get 2 nights at 10cm for 7+ hours per night on a 97Wh battery.
• However if I dial down the pressure to 8cm I can easily get 3 nights at 6 hours per night on a 97Wh battery.
• On a recent (July 2020) 7 night backpack (at 6000' to 7000' elevation) with two 97Wh batteries I dialed down the pressure to 7cm for 4.5 hrs and obtained closer to 4 nights from a 97Wh battery.
• I have found that I can reduce my pressure in the 10cm to 7.5cm range and reduce my hours to 5.5 hours and still feel rested in the morning and can function effectively for the day.
• I have been crosschecking the Z1 data in the HDM DataViewer desktop app and have been able to keep my ahi below 5.

That all said, please consider consulting your sleep doctor if adjusting your treatment.

Parts and Build - current simple and cost effective battery system for HDM Z1

There are 3 parts:

• Battery - Power bank with usb-c 15V output ($129.99 per 97Wh),
• Cable - usb-c power delivery 15V cable ($16.99)
• DC connector ($8.99).

Total cost around $155. Just add more batteries ($130) for more nights.

The HDM Z1 requires DC 15V to provide treatment. During measurements with a DC power meter (see optional parts list below) the HDM Z1 at 8cm pressure uses about 0.5A at 15V. The maximum watt usage I have seen is about 8W to 9W. Higher pressure will most likely draw more power. Likewise as I have lowered the pressure the watt usage has gone down.

1. Battery: Power bank with usb-c output at DC 15V
Many new usb-c power banks support usb-c power delivery output at 15V. I have and use both the Anker and Omnicharge power banks. Both powerbank batteries can output usb-c power delivery at 15v dc power which matches the HDM Z1 device requirements. Related note: I did try the HDM Z1 with DC 12V and 16V however the battery safety circuitry *on the omni mobile battery* appears to shutdown when the cpap device tries to power up to provide treatment.

Battery 1 - Anker PowerCore+ 26800mAh PD 45W with 60W PD Charger, Power Delivery Portable Charger Bundle for USB C
https://www.amazon.com/dp/B07XRJZXKY/re ... cFb33C4DRJ
$129.99 for 97Wh

Battery 2 - Omni Mobile 25,600 mAh DC/USB-C Charging Power Bank
https://www.amazon.com/dp/B07SR337PP/re ... jEbPZGNNBR
$129.99 for 92Wh

2. USB-c pd power delivery cable that output 15V 3A
I found a simple usb-c cable that has a built in usb-c power delivery trigger fixed to 15V. Essentially in the cable usb c female connector end there appears to be a small circuit that communicates usb-c pd protocol at one end and outputs DC 15V 3A at the other end. It is a usb-c cable for a surface pro/laptop.

I used the DC power meter to verify the usb-c pd cables surface connector pins output was 15V.

For my current setup I use the usb-c cable with female input so I can customize the total length via the the usb-c cable. Setup is:
* Battery power bank -> usb-c cable (male at both ends) -> usb-c female input cable that triggers 15V -> DC connector -> HDM Z1.

Cable - Surface Connect to USB-C Charging Cable Compatible for Microsoft Surface Pro 7/6/5/4/3 Surface Laptop 1/2, 45W 15V PD Charging Works with PD Power Supply-0.2 Meters
https://www.amazon.com/dp/B07QY3917Z/re ... jEbQTW91JT
$16.99

3. DC Power connector that is compatible with HDM Z1
I cut off the surface connector from the usb-c pd cable, trimmed back the cable covering and saw a red wire and black wire inside. I stripped the plastic from the red and black wires and connected the red to positive and black to negative terminals on a male DC power connector that is compatible with the HDM Z1. Verified that both wires were isolated from each other to preventing shorting. I connected this to the usb-c power bank battery and measured with the DC power meter and verified output was DC 15V. Connected to HDM Z1. Powered up. Started treatment. Draw was in 8W to 9W at 15V.

DC Connector - many options on Amazon
5.5mm x 2.1mm DC Power Connector, Conwork 10-Pack 2.1mm x 5.5mm DC Plug for Led Strip CCTV Camera 1-38V Extension Cable -5 Male & 5 Female
https://www.amazon.com/dp/B01G6EAOZ4/re ... jEbKNCBB7F
$8.99

Optional parts list

DC Power Meter. Great for measuring DC power between components.
JZCreater Watt Meter Power Analyzer, High Precision RC with Digital LCD Screen for voltage (V) current (A) Power (W) Charge(Ah) and Energy (Wh) Measurement 130Amps
https://www.amazon.com/dp/B01LVTST80/re ... cFb5BYF91Q
$16.99

USB-C Power Meter. Great for measuring usb-c charging and power usage.
Eversame 2 in 1 Type C USB Tester Color Screen LCD Digital Multimeter, USB C Voltage Current Voltmeter Amp Volt Ammeter Detector USB Cable Charger Indicator DC3.6-30V/0-5.1A
https://www.amazon.com/dp/B07JYVPLLJ/re ... cFbT2HE6CJ

Wall Charger. Great for charging and using in place of standard HDM H1 standard DC power adapter when travelling.
Anker 30W USB C Charger [GaN] PowerPort Atom PD 1 with 3 Foot Powerline Select USB-C to Lightning Cable Combo, Type-C Power Delivery Wall Charger for iPhone XR/XS Max/X/8, iPad Pro, MacBook, and More
https://www.amazon.com/dp/B07H4MWKTY/re ... cFbV8BCDHA

thanks

Hi Trailbear,

Thank you for your detailed information about power banks for the HDM Z1!
I have also spent a lot of time looking into batteries for off grid trekking.

In your post you are saying, that the Omni Mobile 25600mAh has an output of 15 volt.
But the output is actually 16 Volt (for the omni 20+ you can change it, but it only has a capacity 20.000 capacity)

You are also saying, that you have tried with power banks with an output of 16 volt,
and that it doesn't work with the Z1 machine.

So I am a bit confused.

Just to be sure:
- Have you tried using the omni mobile 25600 battery
both with and without the trigger cable, that converts the output to 15 volt?

- Can it only be used with the conversion trigger cable?

- And how many hours can you get from it?

By the way, if you don't have to board a plane I strongly recommenmd the Maxoak 297 wh battery.
I use it, and I get 7-8 nights on a single charge! I am not sure what the pressure is though. But
nothing beats it.

Anyway, for me the biggest problem now is finding an efficient carry on battery.
I live in Denmark, and I am still not sure what the limitations are for many european airlines.

Cheers
Jasper

Hi Jasper

On the Omni mobile 25600 I tried both the DC output connector and the usb-c output connector to try to run the hdm z1.

DC connector
You are correct in that the omni mobile 25600 DC output connector supports 16V. This was the closest voltage to the hdm z1 15V requirement. I tried this however the hdm z1 did power up briefly (a couple of seconds) on 16V but the omni mobile power management appears to have immediately cut the power. Perhaps as a safeguard.

Usb-c connector
The usb-c output connector supports 15V via a usb-c power delivery trigger. This is the method that I am using.

Number of hours / nights
With the omni when running on 8cm pressure, I got the results below. In summary I can get about 3 nights depending on the number of hours used per night. The Night3's have less treatment hours as the omni battery went empty at 5hr23 on the first run and 4hr42 on the second run. The closer I can get to 6hr of treatment the better.

Omni - 8cm - First run with fully charged battery
Night1 6hr 21min
Night2 7hr 9min
Night3 5hr 23min (the battery went empty)

Omni - 8cm - Second run with fully charged battery
Night1 7hr 47min
Night2 5hr 56min
Night3 4hr 42min (the battery went empty)

On a recent longer backpack of 7 nights I carried two batteries. An Omni charge mobile 25600 which is a 92Wh battery and an Anker 26800 which is a 97Wh. In order to optimize sleep, treatment and battery life, I tried a couple of things.
* I lowered the pressure to 7cm. This worked ok for side sleeping, did not work for me for back sleeping for me. Next time I may try 7.4cm or 7.6cm.
* I used a modified sleep plan of when I was ready to sleep, I would try to rest in my sleeping bag without my cpap for about 30 to 60 min to 90 min to try to begin to drift off to sleep. After that time I would powerup the cpap and start cpap treatment. In the early hours of the morning after about 5 to 6 hours of treatment, I would powerdown the cpap and rest until it was time to get out of the sleeping bag. Using this sleep plan I was able to get 3 nights from the omni and 4 nights from the anker.

Thanks for the info on the Maxoak battery. I'll take a look.

Yes a tough thing are the airline rules and regulations for carry on batteries. I have read 100Wh or less are ok. I have also read that some airline permit two batteries each of 100Wh.

thanks
Trailbear

Hi everybody

I have created a very similar setup for my wife and can confirm that a USB power deliver powerbank together with the Z1/Z2 is what I consider the best camping setup available.

At first I also went for a DIY cable based on a MS Surface 15V decoy. But I have now found a matching cable on Aliexpress that you can just buy and plug in without any customisation.

There are many shops selling essentially the same cable, here is my source:
https://a.aliexpress.com/_eLsMrD

If you can't find it, search for "15V 5525 USB PD cable" or "PDC003"

Actually the plug is a little bit too wide, 5525 means 5.5mm outside an 2.5mm inner diameter. The device actually needs 2.1mm diameter, bit since the wire inside the plug is flexing a bit, it still connects fine.

So all you need is a USB PD powerbank and the cable mentioned above. But please double check that you have ordered the 15V version. 20V cables seem to be much more common for laptop use. 20V might fry your CPAP, so please be careful.

Some more battery info: Our camping setup has a LiFePO4 Battery (4 cells in series) that usually delivers around 13V. I can confirm that the device will turn on on 13V, but it's much harder to breathe out since the algorithm seems to be disturbed by the lack of voltage. That's why we use a cigarette lighter converter with USB PD interface to boost up to 15V. Be careful when selecting such a plug, a lot of the cheap plugs are step down only. This means they need a 24V truck battery to reach 15V.

We also have bought a very powerful 100Wh powerbank called Zendure Supertank. The goal was to have a powerbank that recharges as fast as possible. The Zendure takes about 1.5 hours from 0 to 80% which is very fast. Of course you also need a beefy charger that puts out at least 80W.

One night on APAP with pressure set to 5cm consumes less than 20Wh. We have to recharge every 4 days, since the actual usable capacity of the 100Wh bank is around 80Wh. It's pretty normal that you can never get all the capacity out of a battery due to conversion losses.

Hope this information helps you. I have just signed up here to share this information with you guys. Greetings from Switzerland.

Is this the power bank you are talking about? https://www.amazon.com/Zendure-SuperTan ... B09D7881WY It's listed as 27,000mah, not 100ah.

Yes, that's the Powerbank.

You are mixing up Wh (Watt hours) and Ah (Amp hours).
In short: 27Ah x 3.7V = 99.9Wh

A little less than 100Wh is a quite commen size, because it's the maximum size allowed for a lot of Airlines.

Hello Hey,

Thank you for the link to the cable.
I just ordered one.

Could you tell me how many hours you get from your power bank?

Thanks
Jasper

Just to let you guys know.

I get around 55 hours from my battery on one single charge,
but I can't bring it on the plane!

I am looking for a battery that will give me 24-32 hours based on 8 hours
of sleep per night, and a battery that I can bring on the plane.

Since most planes will let you bring two batteries of 99Wh, that would
mean a week of offline trekking which I am after.

Best,
Jasper

Jas88 wrote: ↑

Fri Oct 02, 2020 2:40 pm

Could you tell me how many hours you get from your power bank?

For my wife 8 hours of sleep consume about 18Wh. Pressure is mostly between 5.0 and 5.5. Since you can't use the full nominal 100Wh due to conversion losses, this means 4 to 5 nights. Of course higher pressure or sleeping longer means higher power consumption.

Maybe you can even buy one at your destination Airport or send it by mail if the airline limits are too low for you.
Solar charging during the trip might also be an option, but I havn't found a good foldable panel with low conversion losses so far. But that's another story.

Side note: If you are not looking for fast recharge capability, a much cheaper 100Wh Powerbank then the Zendure will do. I think the stock power supply is 45W (3Ax15V), so this is also what most PD powerbanks can deliver. 3A and therefore 45W at 15V is a common limit on PD devices because you need a special active USB-C cable to go higher up until the max limit of 5A.

Can you say where you found the information that "The HDM Z1 requires DC 15V to provide treatment".

Obviously it is working fine with the 15V PD regulated input, per your own experiments / experience. I am just wondering where the optimal / supported input voltage is specified. I can't find anything in the user's manual.

And does anyone know if there are any differences between the Z1 or Z2 with regards to input voltage?

Thanks.

The power supply provided with the device is 15V.
The official lithium ion battery pack is 4S2P and has a nominal voltage of 14.4V.
Also the same battery is available for Z1 and Z2, so I don't think there is any difference regarding the voltage required.

Hey is correct in that the z1/z2 wall ac adapter takes in ac 100V to 240V 1A and outputs dc 15V 2A max.

I also put a dc power meter between the wall adapter and the z1 and verified 15v output at 0.5A to 0.6A.

I also tried to get the z1 to provide pressure treatment at 12v and 16v however was not successful. Only 15V worked.

On 12v the z1 would power up and supply pressure however the z1 breathing out pressure compensation did not work.

On 16v the z1 would power up however either the z1 or the Omni power bank would immediately cut power.

Hello Hey mentions above that he has a cigarette lighter converter with USB PD interface to boost up to 15V and I would love to know where I can find one of these. Any suggestions would be appreciated. I have purchased a z2 and Zendure Supertank along with a 15v USB PD cable based largely on the recommendations in this thread so thank you - I'm looking forward to backpacking with this setup!

Hi Pacoverde

I hope you will enjoy your trips with your new equipment.

In general you can search for "usb pd car charger" on any bigger shopping platform like Amazon, Ebay, Aliexpress.

You should aim for one that delivers 3A at 15V = 45W on the PD side. Some sellers advertise bigger numbers by adding up the capabilities of each port. So make sure that one PD port alone delivers 45W or higher and not all of them together.

But if it says 15V in the description, you are not yet on the safe side. As mentioned, some plugs only can transfer the voltage downwards and only deliver 15V with a 24V input from trucks. So make sure to read the description carefully. If it mentions "buck" or "step down" in the description, don't buy. Also if it mentions to be only fully working with 24V or Trucks, don't buy.
If it mentions "step up" or "boost" converter, then you are safe to buy. Also if it mentions both ways like "buck/boost" you are safe. If it doesn't mention any of those things, you might be able to find an answer in the reviews.

This is one of the plugs that I have bought:
https://a.aliexpress.com/_mKZzPqL

You can find it also under different labels on different platforms. The form is unique enough to recognize it even if it's sold under a different brand.

Regards,
Hey

I maybe also should mention those 2 converters here that I am using right now. Not just for the CPAP but also for a laptop and even a second monitor.

https://a.aliexpress.com/_msDMit9
https://a.aliexpress.com/_mtOPFE3

Those are not cigarette lighter plugs but they basically do the same thing. The difference is that they have a much better heat management. They have metal housing with cooling fins and the heat is not trapped in a cigarette lighter plug hole. Another reason for overheating is a poor connection between plug and socket. This is an issue that exists because a cigarette lighter socket was designed to heat up a cigarette lighter and not to be a good electrical plug design.

Bottom line: You will find a lot of complaints in the reviews about melting or bending cigarette lighter plugs. Especially if the users run them under the full load for long periods of time.

Also I like that those two devices have a standard 5.5mm barrel plug as an input. This means better electric connection on a much smaller plug. And you can still attach a cigarette plug to 5525 cable if you want to use it in a car.

BTW: Sorry if all my posts are advertising Aliexpress, but in my country this is the best source for electronics stuff like this. I am sure this depends on where you live.