power draw difference in Resmed s9

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polyborus
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power draw difference in Resmed s9

Post by polyborus » Tue Jan 24, 2023 1:49 pm

I have a Resmed s9 elite H51 (standard hose not heated hose) that I use for camping since it draws less power on my backup battery pack than does the Resmed 10 I use at home. I have a camping friend who also has sleep apnea and uses the same model Resmed s9 but with heated hose. We have the exact same backup battery. She gets 3 nights from the battery pack with heat set around 68 and humidity at 3. Using the same battery pack, no heat, humidity 3, I get 8 hours. We both use about 9.5 pressure

Thinking I might have a defective battery, we traded batteries for a while. Same result...she gets 3x the duration. So I'm seeking technical help on what parameters I might look at within the s9 to understand this discrepancy. Since my local provider of Resmed equipment no longer sells the Resmed s9, they will not address my question. I'm getting a total run-around from Resmed tech support. I know it's a discontinued machine but recently enough that there are still a lot of us using them. Can anyone give me advice or possibly a referral to some entity that might be willing to address this question?

Many many thanks. I really don't want to give up boondock camping just because I have apnea.

tyrinryan
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Re: power draw difference in Resmed s9

Post by tyrinryan » Tue Jan 24, 2023 5:44 pm

I bought myself a plug-in amp/volt/watt meter on amazon recently. (you plug the meter in and then plug any any small appliance plug into the meter). So I plugged in the S9. I always thought that by holding down the left hand button for 3 seconds, it was effective in turning off the power to the whole s9 setup but the meter showed me that the 3 sec hold just turns off the light. And the converter brick, I guess, still pulls power. This very inexpensive meter is quite good at checking the "amps" pulled at any time by the machine/ converter brick. I think, if you bought one, you would be able to solve the mystery. Of course this only works on 120 v AC but it might be helpful.

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chunkyfrog
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Re: power draw difference in Resmed s9

Post by chunkyfrog » Tue Jan 24, 2023 6:10 pm

What are the pressure settings of both machines?

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polyborus
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Re: power draw difference in Resmed s9

Post by polyborus » Tue Jan 24, 2023 6:27 pm

we are both 9.6

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palerider
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Re: power draw difference in Resmed s9

Post by palerider » Tue Jan 24, 2023 7:57 pm

polyborus wrote:
Tue Jan 24, 2023 1:49 pm
We have the exact same backup battery. She gets 3 nights from the battery pack with heat set around 68 and humidity at 3. Using the same battery pack, no heat, humidity 3, I get 8 hours. We both use about 9.5 pressure
Getting about 1 night of battery use with heated humidity is actually pretty much expected.

The only eye raising bit is her allegedly getting 3 nights especially when adding in a heated hose.

What kind of battery setup do you have, exactly what battery?

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polyborus
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Re: power draw difference in Resmed s9

Post by polyborus » Tue Jan 24, 2023 10:13 pm

At first I didn't quite believer her either, but she actually does get 3 nights. When we traded batteries just to see if mine might be defective, she returned mine after a 10-hour night with 73% charge left. I ran hers down to zero in a scant 8 hours. So it seems to be the CPAP, not the batteries
My main van power pack is a Yeti Goal Zero with 3 charging options (from car cigarette lighter, from solar, from AC house current). I can get a good 8 hour night with my CPAP from that, but in the winter or if camping in a steep-sided canyon, I may not get enough sunlight for a full Goal Zero solar charge...so, for a back-up, I bought (at my girlfriend's suggestion) a Maxoak 5 which had very good reviews. It is this back-up battery I mentioned we now each have, with her resmed s9 + Maxoak duo getting 3x the duration that my same combo gets. We're both stymied.

We've tried to approach this empirically to no avail. The only uncontrolled variables that we haven't considered are ambient conditions. Perhaps her 27' airstream and my 16' camper van maintain significantly different inside temperatures and humidities, such that my CPAP has to work harder. We'll do more experimenting in an upcoming extended boondock in February.

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palerider
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Re: power draw difference in Resmed s9

Post by palerider » Tue Jan 24, 2023 11:43 pm

polyborus wrote:
Tue Jan 24, 2023 10:13 pm
I bought (at my girlfriend's suggestion) a Maxoak 5 which had very good reviews. It is this back-up battery I mentioned we now each have, with her resmed s9 + Maxoak duo getting 3x the duration that my same combo gets. We're both stymied.
The maxoak k5 is only 297 watthours, I'd expect it to last about three nights without heated humdity or heated hose. It will not last more than a night if you're using heat.

It sounds to me like her machine isn't using heated hose or heated humidity, and yours is.

A machine will use around 90 watthours *without* heat, with it, hundreds of watthours, most of the current draw is heating water.

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as10fh
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Re: power draw difference in Resmed s9

Post by as10fh » Wed Jan 25, 2023 5:37 am

The obvious difference is the heated hose. ResMed has a temperature sensor there. If the temperature is set at 20°C and depending on the ambient conditions it may well be that the heating of the humidifier will be throttled to not exceed the set temperature - as opposed to a fixed setting of 3 without the temperature sensor.
You should be able to achieve comparable results with a heated hose. (provided that the leakage would also be identical)

polyborus
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Re: power draw difference in Resmed s9

Post by polyborus » Wed Jan 25, 2023 8:34 am

She is definitely using the heated climateline hose that uses the special additional connector below the basic hose port on the humidifier half of the Resmed s9 H5i. I am using only what came with the CPAP: standard 6' hose, both ends the same, no electric contacts at one end. Unfortunately, one cannot say definitively, from afar, what she 'can' get, durationwise. She and I have hands-on these pieces of equipment and we are seeing what she 'does' get. ( referring to the "it will not last more than 1 night" below). I agree it defies logic (as far as the variables we have been considering). That is exactly what has driven me to 2 dozen emails and calls to tech support places and finally to this blog to see if others could suggest variables that we have not considered.

I am leaning now toward some influence from external environment (temp and or humidity differences in our respective campers), which we'll be able to measure, if not totally control, in an upcoming camping trip. Then back in the comfort of my home bedroom, I'll be able to manipulate those with a heater and home humidifier and see if my duration on the Maxoak (keeping Resmed parameters the same) changes. It stands to reason that a CPAP would have to work harder (show different power draw) if the room were very cold and or very dry

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palerider
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Re: power draw difference in Resmed s9

Post by palerider » Wed Jan 25, 2023 3:32 pm

as10fh wrote:
Wed Jan 25, 2023 5:37 am
The obvious difference is the heated hose. ResMed has a temperature sensor there. If the temperature is set at 20°C and depending on the ambient conditions it may well be that the heating of the humidifier will be throttled to not exceed the set temperature - as opposed to a fixed setting of 3 without the temperature sensor.
You should be able to achieve comparable results with a heated hose. (provided that the leakage would also be identical)
The heated hose sensor regulates the heat going into the hose, not into the humidifier.

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Re: power draw difference in Resmed s9

Post by palerider » Wed Jan 25, 2023 3:35 pm

polyborus wrote:
Wed Jan 25, 2023 8:34 am
She is definitely using the heated climateline hose that uses the special additional connector below the basic hose port on the humidifier half of the Resmed s9 H5i. I am using only what came with the CPAP: standard 6' hose, both ends the same, no electric contacts at one end. Unfortunately, one cannot say definitively, from afar, what she 'can' get, durationwise. She and I have hands-on these pieces of equipment and we are seeing what she 'does' get. ( referring to the "it will not last more than 1 night" below). I agree it defies logic (as far as the variables we have been considering). That is exactly what has driven me to 2 dozen emails and calls to tech support places and finally to this blog to see if others could suggest variables that we have not considered.

I am leaning now toward some influence from external environment (temp and or humidity differences in our respective campers), which we'll be able to measure, if not totally control, in an upcoming camping trip. Then back in the comfort of my home bedroom, I'll be able to manipulate those with a heater and home humidifier and see if my duration on the Maxoak (keeping Resmed parameters the same) changes. It stands to reason that a CPAP would have to work harder (show different power draw) if the room were very cold and or very dry
What color is the light in her humidifier? maybe the heating element is broken in hers.

Swap humidifiers.

It doesn't defy logic, what you're talking about is purely *impossible* based on the amount of power a heated humidifier draws.
Are you both using the resmed DC converter with your batteries?

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Dog Slobber
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Re: power draw difference in Resmed s9

Post by Dog Slobber » Wed Jan 25, 2023 3:50 pm

You are getting what the ResMed Battery guide suggests you should be getting with an S9 with a humidifier @ 3.

https://document.resmed.com/documents/a ... lo_eng.pdf
S9 - (Pressure 10 - Recommended Battery Size 25 AH , Draw 2.03 amps)

She is getting what the battery guide suggests she should get with no humidifier.
S9 - (Pressure 10 - Recommended Battery Size 7 AH , Draw .55 amps) about 3 times better than you.

There is no way that she is getting three days drawing better than 2 amps. So either you have made a mistake representing her machines configuration, or her humidifier isn't working. Her heated hose also may not be working or the temperature isn't dropping below 68 for the heated hose to kick in.

Assuming you or her haven't made a mistake, run the machine than take the temerature or feel the heating plate on the S9 to see if it's warm.

There is no point in emailing technical support. Basicley what's your complaint?

I'm getting results very close to what the ResMed battery guide says I should, but my friend is getting results three times better.

polyborus
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Re: power draw difference in Resmed s9

Post by polyborus » Wed Jan 25, 2023 6:57 pm

I have forwarded this entire thread to my girlfriend. I will ask her what color her humidifier light is. For running our resmeds on DC, We both use the 3 pin to barrel plug cord that Maxoak supplied (their Maxoak5 battery is geared to CPAPs). This cord id specifically labelled by Maxoak with an attached tag on the cord :"For Resmed s9". We will trade CPAPs on this upcoming camping trip as we tried trading Maxoaks last camping trip. That should be an even better test than merely detaching and trading the humidity tank halves of our Resmed s9s.

My complaint was made clear, I believe, in my first post. To reiterate: it appears we have the same model Resmed on the same settings. We have the same Maxoak 5 battery. The difference between our set-ups is she has a heated hose and I do not. She truly gets 3 nights. I have seen her battery numbers. I get 8 hrs.

As an aside, I had looked at various CPAP back-up batteries when I first got my CPAP 3 years ago. I didn't see any that provided more than a night's power. Some months ago when my girlfriend mentioned getting 3 nights from her Maxoak5, I read several dozen reviews of it before purchasing. A number of reviewers mentioned getting 3 days. Had they not, I would have had some serious conversations with my friend. As is often the case in reviews, few specified their exact CPAP and temp/pressure/humidity use and many other reviewers that got 3 days, said they could not use their heat and humidity. SO, there are other campers out there who get multiple nights from their Maxoak5, albeit with scaled down CPAP use...or maybe they too are delusional.

Perhaps her CPAP is broken as a poster suggested. I have sent her a copy of this thread and a separate email about the light on her humidifier and the possibility her CPAP is broken, as this will be of concern to her health. If broken, it has been so for several years, as she has been enjoying her Maxoak for years ( I just bought mine a few months ago). Her husband is retired from international scientific equipment sales and has an engineering mind, He's also a whiz at solar stuff and AC/DC conversion, so he's been watching over our various experiments to track down this discrepancy and will, of course, be very concerned about the suggestion that her machine might be broken.

Perhaps I am paranoid, but I'm getting a whiff of, at best, "one of you is lying" or at worst "Two bimbos who don't know what they are talking about". I didn't think this thread ( or, realistically, a few posters on this thread) would lead me to think I need post credentials for seeking info on an honest problem. I'm a retired Ivy league academic (Princeton, Harvard)....it was a scientific field. Not electrical engineering, but I am thoroughly conversant with the scientific method and can set up and carry through basic experiments, verifying and controlling the variables. My friend is retired from law enforcement and later, the ministry. She is tough-minded, logical and ethical (not intentionally mis-representing her CPAP/battery situation). If we do find her system has been broken, it is a no blame situation and I thank this blog in advance for suggesting this be looked into, as it is important to her health

I would, however, like to close this reply with an observation I made very early in my own scientific career, solidified by a lot of reading in history of science: The words "This just can't BE", spoken either by the original observer or by would-be detractor scientific peers, have led to some of the most creative science and remarkable discoveries made by mankind.

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Dog Slobber
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Re: power draw difference in Resmed s9

Post by Dog Slobber » Wed Jan 25, 2023 7:28 pm

If you are so acquainted with the scientific method, then why are you so offended at the thought of peer review and scrutinizing of method, process and measurement.

Nobody suggested (prior to this post) that you or she were liars or bimbos.

polyborus
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Re: power draw difference in Resmed s9

Post by polyborus » Wed Jan 25, 2023 7:39 pm

Not in the least offended at at " the thought of peer review and scrutinizing of method, process and measurement." Those are the exact things I requested when I asked for suggestions in my original post. That original post could very well be read: "What we are seeing makes no sense to us. Can anyone out there suggest variables we are not looking at?"

I do get a bit upset when I (and my GF) have sat with the very batteries and CPAPs in our hands, have used them on our bodies, have read the 'depletion' numbers on our battery screens and then a poster from afar tells me "This can't be" and "This is physically impossible"