CPAP Backup Power Device ??

raftergirl wrote:I'm curious to see what happens. My friend said his PR machine wouldn't run off his battery with the humidifier attached, so I wonder if mine will work? His is an older machine. I'll keep you posted.

The battery chosen will have to have amps sufficient to supply enuff current at start-up. The current needed after start up wiil be less.

If you have two of the insufficient batteries you can try connecting negative to negative and positive to positive (that is called a parallel connection) to see if that will help; else turn OFF (or disconnect) the humidifier then start the cpap. Any heated hose should also be turned OFF. The heated hose setting is often forgotten. As is the heat for the humidifier.

The older machines seemed to start with about a 5 amp draw at startup. The newer machines seem to want a bit more esp the 60 series from Respironics. Probably cuz of the addition of the heated hose and maybe different motors inside needing more power initially.

I'm using a 20A battery, which is also what my friend uses. His PR machine is about 3-4 years old and does not have a heated hose. I would think that a 20A should be sufficient to run the machine and humidifier. I'll make sure I'm in pass over mode with no heat when I try it out.

I haven't got a BiPAP, just an apap running in CPAP-Mode, 8mb. It runs on a 24AH LiFePO4 battery about 24h with 20% left. Maybe it needs 5-6 A for starting, maybe. My multimeter doesn't work any more, so I can't measure it exactly. But _with_ humidifier/setting 2, w/o heated hose the device needs less than 1A! The original cord has an 8 A-fuse. So it can't take more than 8 A, even while starting.

Why not an expensive battery? A lead battery or a LiIon will give about 300 cycles, after them they will have reduced their capacity to 80%. My LiFePO4 should give about 1400 cycles to 80% capacity! - My battery was expensive as an original Respironic-pack! The Respironic-pack has only 14 AH, it's position-sensitive because it is not even a solid state battery! The weight of mine is about the half!

I don't remember if I am allowed to post url's here ... What about two ore three of these batteries (Amazon):
'Bioenno Power 12V, 12Ah Lithium Iron Phosphate (LiFePO4) Battery with Bundled AC-to-DC Charger'
There should be a lot of better or similar offers, you live in America! I have had the difficulty to import my battery - Germany is only a small spot on the earth.

If the battery _must_ be really lightweight I would prefer a Deben/Tracer (UK) 22 AH LiPo-battery at 1.3 kg.

We live for our vacations! Two nights in a European hotel - the price of a fine battery for many years and the freedom associated with it.

Sorry, my English must be awful.

fat rat

raftergirl wrote:I'm using a 20A battery, which is also what my friend uses. His PR machine is about 3-4 years old and does not have a heated hose. I would think that a 20A should be sufficient to run the machine and humidifier. I'll make sure I'm in pass over mode with no heat when I try it out.

Yes, it should - provided in was fully charged before use AND it will hold the charge. A voltmeter across the battery on startup will show what is wrong.

The only other thing I can think of (if battery is healthy) would be something limiting the current to the machine such as a bad connection or wire which is too small to handle the current draw.

I've been wanting to comment on a number of small items in this thread:

Moondawg wrote:... Would most appreciate suggestion/s as to an effective power backup for my CPAP plus Humidifier. ... I HOPE the answer is not a deep cell marine battery!

The term "marine" is a red herring. A backup battery MUST be DEEP CYCLE. Some marine batteries are, some are not. The only reason marine gets mentioned is that the most bang for the buck (i.e. the most AmpHours per dollar) is with a Walmart etc. marine deep cycle which can be had for about $80 for 100 Amp Hours. These are quite popular with weekend fishermen but long distance cruisers who are cycling their batteries every day use industrial style batteries from quality companies like Trojan. I get my batteries from a golf cart supply company.

Pugsy wrote:...The 60series machines use more power.

I thought the conclusion from the JohnO thread was that the C9 used more power than the Series 60.

raftergirl wrote:Thanks for that link to the Owell battery Pugsy. I had not read that thread before, and was amazed at the hours he got from it. Way more than what the website predicted based on pressure settings.

Unfortunately there is a serious problem with the data supplied by JohnO in the thread. Although he is emphatic that this included the humidifier, he admits in a later post the the room was well humidified by a whole house humidifier. Since the Series 60 senses the ambient humidity, it probably never turned on. In his words: "My room is pretty well humidified." The Owell battery is about 20 AmpHours, so there's no surprise that it could run 4 or 5 nights at modest pressures. But if it tried to humidify in a dry environment it would be dead in one night.

raftergirl wrote:Here's another alternative. I was given this link by another rafter who uses cpap. These batteries [LiFePO] might be a good compromise. Not quite as expensive as the Li Ion, but much lighter and slightly smaller than my Deep Cycle AGM. 6.6 lb. for the 12V20A vs mine at 13 lb. Another plus is that they are much better suited to being discharged below 50% vs the AGM batteries, and they have a much longer lifetime of charging. I might think about one of these in the 12A version (3 lb.) for my kayak touring where I definitely need a smaller & lighter battery. Perhaps I'll replace all my AGM with these in the future????

Its true that AGM batteries do not like being discharged to zero, but a quality AGM such as a Trojan can handle 500 cycles down to 20%. This is far more than the average user would expect with occasional backup service. For the price of one 20 AmpHour Lithium battery, one can get 80-100 AmpHours of Trojan AGM power. Of course, the Lithium battery will be 5-7 pounds, while the AGM will be 50-60 pounds - this will be significant for kayaking, but not for home backup.

Since running with real humidity will take at least 20-25 AmpHours a night, a backup that can handle a few nights in nasty conditions (ice storm, hurricane, etc) should be 50 AmpHours or more. I don't know what objection the original poster (Moondawg) has to "deep cell marine" - if its weight then Lithium is the answer, but the cost runs $250-300 for even 20 AmpHours. If its the mess of a cheap flooded battery, then the AGM is reasonable and but will cost more. Raftergirl's multible 20AH AGM solution works for her particular issue of minimizing weight while providing flexibity, but for home use a single battery sized for the expected need is much better. (Other than weight issues, its generally best to oversize batteries - they charge faster and last longer.) My home solution is a small AGM that sees more service as a hobby power supply, and can be recharged with my portable generator if needed for more than a night. But I don't need humidity so I can get away with only 20 AH; if you need more, a quality 80 AH AGM such as a Trojan is about $240.

BTW, I generally don't worry about humidity because in my part of the country (coastal New England) the biggest risk for extended power outage is a hurricane, which usually brings humidity. However, if your worry is ice storms, humidity is an issue.

CapnLoki wrote: Pugsy wrote:...The 60series machines use more power.


I thought the conclusion from the JohnO thread was that the C9 used more power than the Series 60.

I was comparing 60 series to 50 Series Respironics...not the ResMed machines at all.
So let's make that clear okay?

Pugsy wrote:

CapnLoki wrote: Pugsy wrote:...The 60series machines use more power.


I thought the conclusion from the JohnO thread was that the C9 used more power than the Series 60.

I was comparing 60 series to 50 Series Respironics...not the ResMed machines at all.
So let's make that clear okay?

It was clear to me.
The S9 using a DC-DC converter is bound to use excess battery power.

Guest wrote:It was clear to me.
The S9 using a DC-DC converter is bound to use excess battery power.

As to me too but then I can see inside my brain unlike others.
JohnO's experiment never involved a S9. The captain seems to like to point out my errors when it comes to this battery power stuff...which I will the first to admit I don't know a whole lot about but I don't think I ever mentioned JohnO in terms of anything related to Resmed machines...he didn't test a ResMed machine.
Just powering the series humidifier (even if it didn't heat up much as the Captain seems to think it didn't) is still a power hog. That's why they have the higher wattage brick. That's why so many people have to do without any humidifier no matter what the model series. I am simply not going to do without my humidifier at all. Even set to 1 setting I get horrible nasal symptoms...not going to go down that road at all.

I wish I had the money to get one of those batteries and test my 760 all maxed out with humidity settings but I don't.
All I can do is point people to a possible source for power that might satisfy those 60 series power needs and people have to take it from there. I don't get a rebate for each of those battery packs sold.
And I still say....if I was going to get that sort of battery the one John got would be the one I would buy. At least it stands a chance of powering my machine.

I don't think I ever read JohnO's post but it is entirely possible the humidifier never came on.

Another idea for passover would be to add a Fisher Paykel HC 150 in series. All that is needed is the water chamber to increase the surface area of the water; no heater plate would be needed. That could reduce any heat requirements for Pugsy and possibly eliminate them for many others.

I would not use the added volume (chamber & hose) with a hose longer than 6 ft, esp if you are using an auto. (You can I won't.) The added volume will dampen event detection when using a hose over 6 ft.

Pugsy wrote:

CapnLoki wrote: Pugsy wrote:...The 60series machines use more power.


I thought the conclusion from the JohnO thread was that the C9 used more power than the Series 60.

I was comparing 60 series to 50 Series Respironics...not the ResMed machines at all.
So let's make that clear okay?

Sorry Pugsy. I was remembering a comment in that thread that compared (I think) the power needs of a 560, as measured by a Kill-a-Watt, with the reported use of a S9 from the Resmed document.

I've often wondered about the efficiency of the Resmed DC-DC converter. I've assumed about 85%, but that's a random guess.