UPS question: does the Airsense 10 require true sine wave power?

[lynninnj]

All of this has me scratching my head.

We have a UPS to power our pellet stove in case of an outage. It lasts about 15 minutes so it can burn down and exhaust and not fill the house with smoke. I believe it is modified sine wave because hooking up direct to a generator would not give the sine wave necessary to not burn out the "delicate computer board" as the manufacturer put it.

Now in my search for battery backups I am wondering if I also need to be on the lookout to see if there are sine wave specs or not.

And don't the cpap makers specifically make adapters to remove this added burden of sine vs not sine?

I apologize as I don't want to take over someone elses thread but reading the wilderness and this thread I am truly baffled. I would not want to do ANYTHING to burn out my machine early.

[tisket]

From what I can glean, older ResMeds had this thing where the power supply converted AC to DC for the circuitry but also passed AC directly through on another line for use by the humidifier. As a result you had to use a clean sine wave source for these because it was just passing the AC right through to the humidifier. More recent models seem to be all DC inside, and the power supplies are not finicky, so the requirement no longer exists. That's my impression anyway.

I am looking at two different scenarios for myself.

1. Power flickers/brownouts. My computer UPS often clicks during bad weather. I assume it is switching to battery for a moment during a brief power drop. Due to problems I documented in another thread I think these brief interruptions may be messing with my Airsense 10 if they happen in the middle of the night. So I want something I can leave plugged in all the time to protect the machine from these momentary power drops. Minimal battery capacity needed.

2. Hurricanes. It doesn't happen often but once a decade or so here we can lose power for a few days or even weeks due to hurricane damage. For this I think I would need a different device that could power the machine all night. Last time after the first day or so, they got power back at one of our offices so I had a place to recharge my phone. If such a scenario happens again it occurs to me that a big battery pack would be useful since I would be able to recharge it at work during the day. The lithium ion ones are more expensive but much lighter and easier to carry around than the lead acid ones. It's hard to size the lead acid ones because I am not sure what the power draw is for an Airsense 10 with heated tube and humidifier off. However the big ones are fairly expensive so I am not sure if the lithium ones are really that much more now.

Somewhere I got the impression the large lithium ones (like Jackery, Goal Zero Yeti, etc) were not meant to be left plugged in all the time and used like a UPS, but I am not sure.

[lynninnj]

From what I can glean, older ResMeds had this thing where the power supply converted AC to DC for the circuitry but also passed AC directly through on another line for use by the humidifier. As a result you had to use a clean sine wave source for these because it was just passing the AC right through to the humidifier. More recent models seem to be all DC inside, and the power supplies are not finicky, so the requirement no longer exists. That's my impression anyway.

I am looking at two different scenarios for myself.

1. Power flickers/brownouts. My computer UPS often clicks during bad weather. I assume it is switching to battery for a moment during a brief power drop. Due to problems I documented in another thread I think these brief interruptions may be messing with my Airsense 10 if they happen in the middle of the night. So I want something I can leave plugged in all the time to protect the machine from these momentary power drops. Minimal battery capacity needed.

2. Hurricanes. It doesn't happen often but once a decade or so here we can lose power for a few days or even weeks due to hurricane damage. For this I think I would need a different device that could power the machine all night. Last time after the first day or so, they got power back at one of our offices so I had a place to recharge my phone. If such a scenario happens again it occurs to me that a big battery pack would be useful since I would be able to recharge it at work during the day. The lithium ion ones are more expensive but much lighter and easier to carry around than the lead acid ones. It's hard to size the lead acid ones because I am not sure what the power draw is for an Airsense 10 with heated tube and humidifier off. However the big ones are fairly expensive so I am not sure if the lithium ones are really that much more now.

Somewhere I got the impression the large lithium ones (like Jackery, Goal Zero Yeti, etc) were not meant to be left plugged in all the time and used like a UPS, but I am not sure.

good info

thanks

I want to learn more about the lithium iron phosphate batts because I think you might be able to plug in like a ups but also have around a 10 year lifespan. I wont be lugging it around much so if it’s a bit heavier i don’t care

[tisket]

I have also read that leaving lithium batteries at 100% all the time (using as a UPS) will significantly shorten battery life. Not sure how PortableOutlet gets around this. Maybe it's why they only have a one year warranty. Our laptops at work are plugged in all the time and their batteries do lose capacity over time (or even swell up alarmingly).

Seems like it's best to have a small UPS to protect against power drops/surges and another, bigger battery lying around for long term outages like hurricane damage. According to one brand, supposed to top them off every three months or so then let them sit. Letting them drain completely is also bad apparently.

[Grumpy48]

Presuming that most all CPAP power adapters are of the same kind that are used for a laptop (such as those for a DS2 and AS10), these are what are called switched mode power supplies. A switched mode power supply takes the incoming 120-240vac, 50-60hz and immediately rectifies (changes to DC) the voltage and is then filtered/smoothed to take away most all of the AC component that may be left. This rectified DC is then 'switched' on and off at a high frequency through a transformer by a semiconductor device. This transformer feeds another rectifier that changes the output of the transformer back to DC at a low voltage that is usable by the CPAP machine (12vdc, 24vdc, etc). Another piece of the circuitry regulates the DC output voltage by telling the semiconductor 'switch' driving the transformer at what voltage it needs to be. There may be circuitry that protects the power adapter from overload as well. Depending on what the adapter is used for the DC output voltage may be filtered more or less. Some of the DC connecting cords may have ferrite beads to reduce or eliminate RFI (radio frequency interference) from getting into the electronics of the CPAP.
Unless otherwise indicated most all switch mode power adapters will not care if the incoming AC is sinusoidal or non-sinusoidal since the first step in the adapter is change the AC to DC and the rectifier doesn't really care what goes through it. It may be slightly less efficient with non-sinusoidal.

The importance of a pure sine is when using a device with a 'real' transformer (iron and copper) or an electric motor. A pure sine wave has no harmonics (just fundamental 50 or 60hz). A non-sinusoidal AC source may have harmonics (even or odd multiples of the fundamental frequency) components. Transformers and motors are usually designed for specific frequencies to function efficiently. The harmonics in a non-sinusoidal AC source may cause heating of copper windings and iron which eventually may damage them. A transformer supplied with a non-sinusoidal source may emit some noise due to harmonics.
If not sure what you're powering, it's best to err on the side of using a pure sine wave power source.
A pellet stove will likely use a conventional transformer (copper and iron) on its control board and the pellet feed and blower motors all should be supplied with a clean pure sine wave.

In the schematic below of a typical switch mode PS the Mosfet device IRF840 is switching the rectified DC on and off to the transformer.

[tyrinryan]

Tisket: The Resmed Battery Guide has a chart outlining the power draw (Amps) at 12 volts; for the AS10; with heated tube at 30 degrees C; for IPAP set at 10 cc water----as 1.2. The guide suggests a 19 Ahr battery, I think it was to allow for a 50% battery draw down. The chart covers different IPAP pressures, different heat etc. and it was very helpful to me in considering all the options to see how much the power draw varied depending on the settings etc.. Additionally, I understand that the power draw is higher during inhalation vs exhalation and I guess this number is an average.

[tyrinryan]

Grumpy: Thanks for the excellent tech support.

The Resmed Battery Guide gives all kinds of power draw statistics for the AS10 when using a converter but no figures if using an inverter. In addition the Guide specifically says you can use modified sine wave with the stellar series and the s9 series etc. but specifically does not mention the AS10 or the Air Mini. What do you make of that? Do you think the power supplies are different in design?

[tyrinryan]

https://document.resmed.com/en-us/docum ... lo_eng.pdf
is the address of Resmed Battery Guide

[palerider]

if you think my post was spam. I want you to study how electrical equipment works.

Well, someone certainly need to study some electronic operations information.

all circuit boards in medical equipment run better and cooler with pure sine wave.

No, they all run on DC, which is what's supplied by the 24V DC power adapter.

all motors with oxygen,

Oxygen doesn't have a 'motor'.

and c-pap need pure sine to run.

You're blaring your ignorance again. The S9, Airsense 10 and Airsense 11 blower motors run on variable frequency THREE PHASE power.

if you try to run them on modified, your equipment won't last. they burn out from excessive heat. listen to any motor that runs on modified. it hums and runs hotter. look at lights. they flicker. all computers need pure sine wave to run the right way. all medical equipment needs pure sine. if you don't believe me. look in your owners manual. if you want to run modified. its ok with me. I care less what you do. I'm going to tell them the right way. look for pure sine.

You have no idea what you're talking about.

Please just stop, because your galloping ignorance is misleading to those that don't know how full of crap you are.

[palerider]

A brief overview of the basic operating principles of modern switch mode power supplies.

THIS person knows what they're talking about.

[icipher]

Presuming that most all CPAP power adapters are of the same kind that are used for a laptop (such as those for a DS2 and AS10), these are what are called switched mode power supplies. A switched mode power supply takes the incoming 120-240vac, 50-60hz and immediately rectifies (changes to DC) the voltage and is then filtered/smoothed to take away most all of the AC component that may be left. This rectified DC is then 'switched' on and off at a high frequency through a transformer by a semiconductor device. This transformer feeds another rectifier that changes the output of the transformer back to DC at a low voltage that is usable by the CPAP machine (12vdc, 24vdc, etc). Another piece of the circuitry regulates the DC output voltage by telling the semiconductor 'switch' driving the transformer at what voltage it needs to be. There may be circuitry that protects the power adapter from overload as well. Depending on what the adapter is used for the DC output voltage may be filtered more or less. Some of the DC connecting cords may have ferrite beads to reduce or eliminate RFI (radio frequency interference) from getting into the electronics of the CPAP.
Unless otherwise indicated most all switch mode power adapters will not care if the incoming AC is sinusoidal or non-sinusoidal since the first step in the adapter is change the AC to DC and the rectifier doesn't really care what goes through it. It may be slightly less efficient with non-sinusoidal.

The importance of a pure sine is when using a device with a 'real' transformer (iron and copper) or an electric motor. A pure sine wave has no harmonics (just fundamental 50 or 60hz). A non-sinusoidal AC source may have harmonics (even or odd multiples of the fundamental frequency) components. Transformers and motors are usually designed for specific frequencies to function efficiently. The harmonics in a non-sinusoidal AC source may cause heating of copper windings and iron which eventually may damage them. A transformer supplied with a non-sinusoidal source may emit some noise due to harmonics.
If not sure what you're powering, it's best to err on the side of using a pure sine wave power source.
A pellet stove will likely use a conventional transformer (copper and iron) on its control board and the pellet feed and blower motors all should be supplied with a clean pure sine wave.

In the schematic below of a typical switch mode PS the Mosfet device IRF840 is switching the rectified DC on and off to the transformer.

So the short of this is that a CPAP machine shouldn't have an issue dealing with non pure sine wave.

[southerndoc]

Definitely knows their stuff as @palerider mentioned. Or at least knows way more than my understanding of it!

If CPAP machines required sine wave power output, the innumerable users that don't use a sine wave UPS would have already posted about their CPAPs prematurely wearing out or malfunctioning.

Very few electronic devices "require" sine wave output.

[turbo]

As I mentioned earlier. I've been using modified sine with AS10 for a few years now with no issues. I'd post what battery I'm using, but I don't want to spam the board.

[tisket]

Thanks for the info everyone.

[jas32]

As I mentioned earlier. I've been using modified sine with AS10 for a few years now with no issues. I'd post what battery I'm using, but I don't want to spam the board.

Do you mean your CPAP machine is running 100% of the time on the modified sine wave battery power, on extended camping/off the grid trips, or only when normal AC power goes out at home?