Breas Z2: 12 volt vs 15 volt?

I am getting ready for a 14-day backpacking trip on the Mount Rainier Wonderland Trail 3 months from now.

I have been looking at excellent backpacking/camping posts on this forum (thanks!). Most posters supply 15 volts to the Z2, either from a USB-C trigger cable or through a buck/boost module. I know the standard Z2 AC power adapter delivers 15 volts and I think this is what drives most people to supply 15 volts.

However I also see references to the Z1/Z2 cigarette lighter cord that *seems to* deliver just 12 volts (or whatever the auto battery is supplying). This makes me wonder if 15 volts is overkill -- why not use a 12V USB-PD trigger cable rather than 15V? I also can no longer find the Breas cable for sale and wonder why; was there a problem with it?

What is the minimum voltage the Z2 will accept? Why use 15V instead of 12V? Why use USB-C PD instead of just a 12V battery?

Thanks,

Jay


PS: what I've tried so far.
I've been trying supplying power from the cigarette lighter port on the Renogy 266 Watt-hour battery https://www.amazon.com/dp/B0791WDZTW
I was able to sleep 6 nights on the Renogy battery using my old travel machine -- a Transcend II Travel CPAP Machine with Transcend Mobile Power Adapter. It used about 40 watt-hours a night. battery voltage went as low as 10.5 volts as it depleted but the mobile power adapter seemed able to handle it.
I just got a Z2 and am trying the Renogy battery with that, straight from the cigarette lighter port to the 5.5x2.1mm jack; 2 nights so far. The Z2 has used 20 watt-hours a night making me hope for more nights sleep on one battery.
In future posts I will ask about forum members' solar charging experience

In future posts--in THIS thread, please.

Chunky I think you forgot to post the link to the thread you were referring to?

I could be wrong but pretty sure I read somewhere the the unit will shut down around 12vdc. So when your battery starts to get depleted the voltage gets low enough that the cpap turns off. I think people were not getting full use of their battery capacity because of this. If you run the machine off 14-15vdc then as the battery depletes and the voltage starts to drop the machine will not turn off and can actually keep going even if you run the battery all the way down to 12vdc. Thats not something you should do though to maintain a long battery life. I think that is what is going on and why people are running them at a higher voltage. Don't quote me on that though.

I copied this from someones post on another thread.

"
Technical Notes:
- The Z1 (and Z2) are designed as 15VDC devices with a min voltage of 11.8VDC (before it shuts down) and a max voltage of 16.5VDC
- Max amperage = 2A
- Power uses a 2.1mm x 5.5mm plug
- The Z2 has the same specifications as the Z1, only the fan motor is quieter and the electronics were redesigned to incorporate improvements they have discovered. (For example, in the Z1 if the internal battery dies and the machine cannot store data, it throws a Fault 33 and shuts down the machine. In the improved Z2 design if that happens the machine continues working but just won't store data)
"

This tells me it should run 12vdc. I'm also curious to know the real answer of 12v vs 15v.

Thanks for that Rob. I missed the post you mentioned with the 11.8 - 16.5 V range.

Glad you mentioned the error 33. I assume there's some way to reset it once it gets that.

No idea on the error 33.

I have a power supply that allows me to adjust the voltage. My Z2 Auto runs at 11.8vdc and any lower than that it will shut off in a minute. I tested from 16vdc down 12vdc and noticed the motor runs slower as you turn down the voltage which also decreases the pressure at the mask a little.

Also if you are running on 12vdc and using the Z Breathe exhale relief at a setting 3 there is quite a delay in response before the machine changes pressure. The motor is not as responsive at 12vdc. If you used the Z-Breathe at setting 3 than I think you would want to run the machine closer to 15vdc. When I set the Z-Breathe to a setting of 1 than the exhale relief response seems to stay the same no matter the voltage.

I'm going to take a bunch of the info I posted over to my thread. Might as well continue on with everything in one place and let this thread pass. We basically are on the same subject on both threads now. If would be good to keep everything together so it's easier for people to find the info they need in the future. Makes no sense to rehash everything. I think that's what Chunkyfrog was referring to.
viewtopic/t184073/Cpap-for-extended-wil ... l?start=15

glacierjay wrote: ↑

Sun May 01, 2022 10:07 am

However I also see references to the Z1/Z2 cigarette lighter cord that *seems to* deliver just 12 volts (or whatever the auto battery is supplying).

I forgot to mention that the cigarette lighter adapter cord that they sell for the z1/z2 machines is intended for charging the Power Shell battery while in the power shell and not for running the machine. The cord plugs into the Power Shell. I suspect their is a boost circuit in the power shell to convert 12vdc from the car to 15vdc to charge the Power Shell battery pack. Chances are the vehicle has to be running which give a voltage around 14vdc at the cig socket. Makes me wonder if you can run the machine while charging it at the same time. Would have to ask the manufacturer.




Here's the definitive answer on voltage requirements right from the manufacturer:

"The Z2 unit will not run off of 12V DC. The unit needs to run off of 14.4-15V. Anything 30W + of power capability and 110V AC will run the unit. Please let me know if you have any further questions. Have a wonderful day and take care. "

Best Regards,

Brandy Wright
Customer Support Specialist
Breas Medical, Inc

My experience with a Z1 auto is that it will not make it through the night at 12 volts. It will eventually stop within a few hours. I have had success running it with a 16 volt power brick while camping. It has worked well on many trips and I don't need to carry the 120v power adapter. The power source I am using is called a V88 on amazon.

glacierjay wrote: ↑

Sun May 01, 2022 10:07 am

I am getting ready for a 14-day backpacking trip on the Mount Rainier Wonderland Trail 3 months from now.

Have you done a trial of sleeping at those elevations? Your body may react differently than sleeping at lower altitudes.