CPAP or APAP on a battery

[litetrek]

I'm a backpacker and I'm going on an overnight next weekend. I run my z2 in cpap mode and my prescribed pressure is 14 cm. I don't have time to experiment with a lower pressure setting before next weekend so I need to get the most from whatever battery I buy.

I did some measuring for a week and my z2 in cpap mode set at 14 cm uses between 5.5 amp-hrs and 7 amp-hrs a night. So a 30,000 mah battery with PD using a 15v trigger cable should "almost" get me 8 hrs based on the numbers I've measured from my Anker power bank and the numbers I've seen here. Would running in APAP mode reduce my amp-hour requirement??? A while back I read that it actually consumes more power to run in APAP mode but I've never verified that.

I'm planning on buying a baseus 30,000 mah battery, btw. The price is right and I consider it an experiment. If I can get 1 night out of it I'll be happy. However, I won't be suprised if I only get about 7 hrs.

[zonker]

I'm a backpacker and I'm going on an overnight next weekend. I run my z2 in cpap mode and my prescribed pressure is 14 cm.

maybe you can find an answer here-
viewtopic/t179963/Battery-solution-for- ... usage.html

good luck!

[litetrek]

I'm a backpacker and I'm going on an overnight next weekend. I run my z2 in cpap mode and my prescribed pressure is 14 cm.

maybe you can find an answer here-
viewtopic/t179963/Battery-solution-for- ... usage.html

good luck!

Thanks I've already read all of that before I posted my question.

[amenite]

30,000 mah battery

Amp Hours is a pretty useless measure unless one knows the voltage that the number is based on. Is that 30,000 mah at 5V? 12V? 24V? Big differences there. Do yourself a favor and do like that poster does in that other thread - use Watt Hours for everything. And don't buy any battery that does not have a watt hour rating.

[Rob K]

The blower motor in the pap machine is what consumes the bulk of the needed power. The faster it runs the more current it draws and the more electricity it uses, the slower it runs the less electricity it uses. In order to save on battery the blower motor would need to run slower, in other words the pressure would have to be lower. Everyone is different, some can get away with a little less pressure and increased events and others cannot.

The amount of power used in apap mode is going to be determined by the pressure settings and your requirements each night as your apnea changes. The speed of the blower motor will change when the machine ramps the pressure up or down through the night. If you can get away with less than 14cm of pressure than the amount of power used should be reduced. If your going to need more than 14cm this will increase the amount of power used. The only way to know is to do the test, look at your data in the morning and see how your feel.

[Rob K]

A bit on power banks. If your lucky the seller will list the watt hours. Watt Hours is what you want to figure out, that is the most relevant rating when looking at battery capacity. Watt hours will be relatively the same no matter what voltage you choose to run it at which can be widely different depending on what device you will be plugging in. That's why watt hours are a better indicator of power bank capacity.

A lot of sellers will list just the amp hours but you also need to know what voltage that rating is figured at. Most power banks are rated at the internal battery voltage which is around 3.7vdc for lithium cells. The Baseus 30,000 milliamp hour power bank is rated at 30,000mah@3.8vdc.

Doing the math:
30000mah/1000 =30amphours
30ah x 3.8vdc=114watthours

You can also reverse this to figure out the amp hours when running your Z2 at 15vdc:
114wh/15vdc = 7.6ah
7.6ah x 1000 = 7600mah
So the Baseus power bank capacity is actually 7600mah@15vdc
Of course you will get less than this under actual real world use.

114wh is the theoretical total battery capacity. No two batteries are exactly the same. Some of that capacity will be lost converting to 3.8vdc to 15vdc. To extend battery life you don't want to completely drain it so actual capacity will be less than 114wh.

When I ran my Z2 on my Baseus 30000mah power bank I pretty much ignored the display since it does not seem very accurate. I charged it until it stopped drawing current and discharged it to where it shut down. I measured battery capacity at around 104wh. Operating it like this is pushing it to the extreme and will shorten the life of the battery, but it shows the maximum that you can get out of this power bank.

Doing the real world math:
104wh/15vdc = 6.93ah
This is around the maximum that you can expect to get out of the power bank if you use it in the way that I did by operating it to the limits. If you want your power bank to last longer don't operate it to the limits. Capacity will decrease as the batteries age and pushing them to the limits makes this happen faster.

Edit: I just realized Baseus has more than one 30,000mah power bank. The one I was talking about above is the Baseus 30000mah 65w power bank with the round windowed display.

[litetrek]

30,000 mah battery

Amp Hours is a pretty useless measure unless one knows the voltage that the number is based on. Is that 30,000 mah at 5V? 12V? 24V? Big differences there. Do yourself a favor and do like that poster does in that other thread - use Watt Hours for everything. And don't buy any battery that does not have a watt hour rating.

Thanks I realize that and I know the science. The Baseus 30000 amp hr battery is what is referred to specifically in the thread about backcountry cpap use. That battery was very rigorously tested by several people.

[litetrek]

A bit on power banks. If your lucky the seller will list the watt hours. Watt Hours is what you want to figure out, that is the most relevant rating when looking at battery capacity. Watt hours will be relatively the same no matter what voltage you choose to run it at which can be widely different depending on what device you will be plugging in. That's why watt hours are a better indicator of battery capacity.

A lot of sellers will list just the amp hours but you also need to know what voltage that rating is figured at. Most power banks are rated at the internal battery voltage which is around 3.7vdc for lithium cells. The Baseus 30,000 milliamp hour power bank is rated at 30,000mah@3.8vdc.

Doing the math:
30000mah/1000 =30amphours
30ah x 3.8vdc=114watthours

You can also reverse this to figure out the amp hours when running your Z2 at 15vdc:
114wh/15vdc = 7.6ah
7.6ah x 1000 = 7600mah
So the Baseus power bank capacity is actually 7600mah@15vdc
Of course you will get less than this under actual real world use.

114wh is the theoretical total battery capacity. No two batteries are exactly the same. Some of that capacity will be lost converting to 3.8vdc to 15vdc. To extend battery life you don't want to completely drain it so actual capacity will be less than 114wh.

When I ran my Z2 on my Baseus 30000mah power bank I pretty much ignored the display since it does not seem very accurate. I charged it until it stopped drawing current and discharged it to where it shut down. I measured battery capacity at around 104wh. Operating it like this is pushing it to the extreme and will shorten the life of the battery, but it shows the maximum that you can get out of this power bank.

Doing the real world math:
104wh/15vdc = 6.93ah
This is around the maximum that you can expect to get out of the power bank if you use it in the way that I did by operating it to the limits. If you want your power bank to last longer don't operate it to the limits. Capacity will decrease as the batteries age and pushing them to the limits makes this happen faster.

Edit: I just realized Baseus has more than one 30,000mah power bank. The one was talking about above what the Baseus 30000mah 65w power bank with the round windowed display.

Thanks RonK. I have an engineering degree and understand the science and math. I understand that a lot people don't know the science so its important to explain it. Most cpap users don't realize a) that the rating on the batteries isn't exactly correct and can be way off b) that there are resistance and conversion losses c) that a high pressure setting requires a lot more power than a moderate setting d) that inhaling uses more power than exhaling e) that the prescribed pressure setting is somewhat arbitrarily chosen by the doctor to get the measured apnea events below an acceptable number (a lower pressure could also be adequate).

Your thread(s) and glacierjay's thread(s) both have a lot of very useful data and I've studied both of the posts extensively. My question was buried in the background info I provided. I highlighted it though. I'm wondering about the power requirements of the Z2 in APAP vs CPAP mode. Which mode requires more power? There may not be an answer to that because it may be different for each person. I would guess that APAP would use less power but I'm not sure about that since some power would be wasted constantly running the algorithm that monitors and controls the pressure
.
My doctor didn't want to prescribe an APAP but when I pushed him he prescribed 14 cm with a 13 cm lower limit (big help right?). I know I backpacking trip.

I use a little device to measure the cumulative current draw and I know from the data I've collected that I use between 5.5 Amp hours and 7 Amp hours per night (8 hrs). This data is based on using the Z2 set at 14cm, a 15V trigger cable, and a big Anker power bank that I use in my RV. So the Baseus 30,000 amp-hr battery with the round window display should get me ABOUT one night. I'm pretty confident with your data and mine that I'll get ABOUT one night with my set up. I just want to know if putting the cpap in APAP mode has any potential for getting a little more operating time out of it.

[ChicagoGranny]

when I pushed him he prescribed 14 cm with a 13 cm lower limit (big help right?).

You know you can easily change those settings? Instructions for your machine on youtube.

[Dog Slobber]

Asking what mode CPAP or APAP uses more energy, doesn't really make sense.

What ever mode spins the blower more will use more power. And that is dependent on what the specific APAP settings are and where the device is all night.

Given the Z2 isn't supported by OSCAR there is no way to tell.

On systems supported by OSCAR, one could take a look at their Med EPAP and IPAP, then average them for CPAP mode and APAP mode. The lower value will consume less energy.

[litetrek]

Asking what mode CPAP or APAP uses more energy, doesn't really make sense.

What ever mode spins the blower more will use more power. And that is dependent on what the specific APAP settings are and where the device is all night.

Given the Z2 isn't supported by OSCAR there is no way to tell.

On systems supported by OSCAR, one could take a look at their Med EPAP and IPAP, then average them for CPAP mode and APAP mode. The lower value will consume less energy.

I agree withn everything you've said. But there are people on this board who use the Z2 prescribed to be set at 14 cm who have compiled data in APAP mode. I know that because it was stated in some threads. Having that data compared to no data at all even if it doesn't apply to my medical situation is better than nothing. I'm hoping someone with a similar set-up will provide some information. Its better to interpolate than extrapolate but sometimes extrapolation is all you've got.

[litetrek]

when I pushed him he prescribed 14 cm with a 13 cm lower limit (big help right?).

You know you can easily change those settings? Instructions for your machine on youtube.

Thanks. I have the clinician's manual and know how to change the settings. So, that is not an issue Currently, I'm intentionally trying to squeeze a full nights sleep out of a battery that is just barely big enough without changing the settings other than CPAP to APAP mode. Its an experiment.

The battery is being delivered today and I get home from a out of town trip tomorrow. So by saturday I'll know if it makes it through the night on my current settings (14 cm cpap) or how far it falls short.

[Rob K]

To answer your question specifically, what you are asking is not possible. You cannot directly compare cpap to apap mode at 14cm. In apap mode the Z2 requires that you select a pressure range of 1/2cm or greater between the high and low settings. Your settings and what pressure the machine decides to run at through the night will determine how much power is used. In apap mode the power used might be less, the same or more depending on settings and requirements through the night.

I would set the range to something like 12-14cm and see if you can get away with a little less pressure. Even though the Z2 is not compatible with Oscar to look at all the detailed data you can at least use the Z2 App and get some basic info. Like AHI number and some crude pressure and apnea graphs. You should be able to discern if the machine is running closer to 12cm, 14cm or somewhere in between. See what your ahi number is in the morning and how you feel. There's a chance you could squeeze more time out of the battery but it will require you to do the test to see if you can get away with lower pressure.

That said I do understand your concern. The Baseus 30000mah 65w power bank is a borderline one night battery for you so your wondering if the purchase will be a waste of money. Unfortunately the only way your going to know is to test it with your personal Z2 settings and tweak things from there to see if you can get more out of it. Of course you could do the test with any battery that you have, but it sounds like your out of time and need to get the Baseus asap. Keep us posted on your tests.

[litetrek]

To answer your question specifically, what you are asking is not possible. You cannot directly compare cpap to apap mode at 14cm. In apap mode the Z2 requires that you select a pressure range of 1/2cm or greater between the high and low settings. Your settings and what pressure the machine decides to run at through the night will determine how much power is used. In apap mode the power used might be less, the same or more depending on settings and requirements through the night.

I would set the range to something like 12-14cm and see if you can get away with a little less pressure. Even though the Z2 is not compatible with Oscar to look at all the detailed data you can at least use the Z2 App and get some basic info. Like AHI number and some crude pressure and apnea graphs. You should be able to discern if the machine is running closer to 12cm, 14cm or somewhere in between. See what your ahi number is in the morning and how you feel. There's a chance you could squeeze more time out of the battery but it will require you to do the test to see if you can get away with lower pressure.

That said I do understand your concern. The Baseus 30000mah 65w power bank is a borderline one night battery for you so your wondering if the purchase will be a waste of money. Unfortunately the only way your going to know is to test it with your personal Z2 settings and tweak things from there to see if you can get more out of it. Of course you could do the test with any battery that you have, but it sounds like your out of time and need to get the Baseus asap. Keep us posted on your tests.

I realize that it is not a direct comparison. However some data, any data, is better than having no data at all. I'm not looking for certainties just something to hang my hat on. I think I can eek out a full nights sleep on that battery. But having some margin would be nice. I am fully capable of testing and tweaking settings and treatment hours etc, but I don't have time to do it before my trip. FYI, my usual solution is to go without cpap. My wife is a nurse and this time she's insisting that I find a solution to enable taking my cpap.

I already bought the battery but I have no time to test it with apap because the battery is at home (arrived today) and I'm out of town. What I'm trying to determine is if I need to carry another power bank. I have an smaller anker power bank that I could take but I'm a borderline ultralight backpacker and all of this stuff is extra weight as you know. An extra battery if not needed is just a waste. I would rather take a steak or have a lighter load than take an extra battery.

Seeing someone's real data would be helpful. If I had time to test I would probably set my machine in apap mode at 14 cm maximum and gradually lower the minimum and see how it affects nightly amp-hrs or watt hrs. In fact I plan to do that after my trip. Lacking that, seeing the results someone else got for doing something similar would be very helpful even though itis not applicable to my medical condition.

[AZdreamer]

I’ll toss in a data point which may or may not be useful. I used my Z2 this past weekend for one night using the HDM/Breas battery (which is rated 99Wh). My settings were APAP, min 12cm, Z-breath 3. I slept for 8+hrs with a 95% pressure of 13. Two bars remained on the battery in the morning meaning, according to the manual, that 35-63% of the charge remained. That suggests to me that a 65Whr battery might just cover one night….