My battery backup setup

[Marthajoy7]

I agree on wire sizes. Size 22-24 stranded wire is only rated for a couple of amps. Could be used for very short runs only. My batteries have Anderson SB50 Connector Kit, Gray on them, as that is what my scooter uses. So I put them on all my portable batteries. I made up a cable that connects 2 batteries in series to a XLR female connector for charging inside. Can make similar with 2 female connectors and use male XLR to power connector. Easy to install resistor inside XLR male connector. This would allow power to multiple machines. Size 16 might be over kill, depends on how long a run you are building. Size 18 seems good to me, but like a say, depends how far away from the batteries you intend to sleep.
What concerns me most, is what happens in a power outage. That means our home is getting cold quickly, and I may very well need lots of heat and humidity from my unit to keep me from freezing. A couple of years ago, we had an outage that lasted almost a week. In winter time no less. Ended up having to stay a while with friends, as could not even endure it at home any longer. It almost had me worried that any outage, would have us packing up and finding a motel somewhere. Even if it turned out to just be for just a half hour. I used an inverter to be able to watch tv till all our batteries were depleted. But either cold food or eat out becomes the norm. Just know I need a backup plan, even if it never is used

[OMyMyOHellYes]

18 AWG is probably pretty much OK for 10 A at 10'~3M. I just happen to keep spools of 16 AWG, 12 AWG or 10 AWG red/black zip cord around......

Heat and humidity from your machine? They are not designed to keep you warm. They are only designed to raise the water temp barely enough to increase the vapor pressure of the water. And much heating would result in heavy condensation (rainout) in a colder room. I say it doesn't make much difference, though I find breathing difficult at higher temp/humidity settings (hotter, more humid air being less dense and carrying less O2). I can breathe better camping in cold climates than I can in more tropical locations.

Sleeping in a cold room with a CPAP does not materially increase your risk of freezing any more than a person not using CPAP. You can pretty well breathe cold air. I actually quite enjoy it in colder winter climes.

OMMOHY

[Marthajoy7]

Question? Why are you thinking 10 amps @ 24 volts? That is 240 watts. There is a 10 amp fuse but my thinking that is protection against accidental shorting. Much as in CB radios had a reverse biased diode on power up. If hooked up correctly, every thing was fine, but if connected backwards, the diode would short taking fuse and likely traces off the circuit board, requiring repair. Because they did not want to drop the input voltage that a series diode would have.

I am being told to expect like 10 watts per device if humidity and heated hose is not used. That would mean less than 1 amp for 2 devices. At 10 amps you would deplete two 40 ah batteries in less than 4 hours. I really do not think, even at units using everything, you are going to be using anywhere near 10 amps @ 24 volts. Even the companies up converter cannot handle 10 amps @ 12 volts, as that would be 120 watts, or even 135 watts @ 13.5 volts.

Since I do not expect 2 fully charged 40 ah batteries to only be good for 4 hours, as I can sleep long hours say 10 at a time. I would like to keep current draw @ 4 amps or less. At 24 volts that is 120 Watts of power. I do not expect that I would ever exceed those limits. So with less than 4 amps being used, yes, one could easily place a 4 amp fuse instead of a 10 amp one, and still not expect it to blow. I doubt the dreamstation used much more than 4 amps @ 12 volts leave alone 14 volts.

[OMyMyOHellYes]

I don't do ANYTING at 24 V DC anymore. I realized the error of my ways and repented to standard 12 V systems. As I don't really use heatedc humidificaiton much, I doubt that I ofetn break two - or maybe even one - amp draw.

10 is a nice round number - and I was using the worst case scenario from ResMed's battery guide as a starting place. They show some configurations at 6-7 A draw for an S-9 like I used to use. So I covered that plus a couple more. Belt and suspenders.

OMMOHY.

[Marthajoy7]

I am not familiar with the S9. Is it 12 volt or 24 volt? A long time ago, I had a respirinics brick that recorded nothing but time used. It was 12 volts and used a few times on battery, Then it started giving my face a infection any time I used it and DME refused to do anything about it. Changing supplies did not help as it was coming from inside the machine. So doctor told me to quit using it. I almost died a little over a year ago and hospital could not get me a machine. So was sent to nursing home where I was told I would be provided one. Well they did not till after about a week when I told them I was going to check myself out with or without their permission unless they got me one. With no one checking on how I was doing and doctors not speaking English. I did check out and took my brick apart and soaked every passage way with alcohol and something not plastic came out of the last elbow before going into humidifier. I was then able to put back together and let it run almost 24 hours to get rid of smell. Used that until finally got a sleep test and was told a cpap wold work when hospital had said I needed a bipap. Well cpap did not work, way to many central apneas. So had another sleep study and now I have an AirCurve 10 Vpap and it is working so much better for me. My mind is starting to function again as long as I keep my oxygen level high enough. In the hospital I had to be intubated and it seems to have damaged my airway, which is why I have COPD and have never smoked. I know without a doubt that I will become non functioning at being able to care for myself unless I used my equipment.
Any way, 6-7 amps at 12 volts equals 3-3.5 amps at 24 volts. So wire size can be smaller.
I have multiple power chairs/scooter that all run on 24 volts. Need to see if I can find schematic of controllers and see if the charging XML can provide current out to run bipap. If so, it will be simple. XML to 7.4mm connector with resistor for sense line. I know there is voltage one the pin open circuit, just do not know if there may be a diode in the way.

[surferdude2]

Now you gotta ask yourself, "Did they put that sense line in there just to be selfish or is it really doing something important?"

Dude

[PoolQ]

If they needed that resistor for anything operational inside the CPAP, they would have just put the resistor inside the CPAP. That goes for the 3 pin power connector and the 3 volt DC at that resistor. Lower cost, fewer problems to just put it all inside the CPAP if it has any purpose other than trying to stop people from using 3rd party power bricks.
But it is what it is

[surferdude2]

We have previously discussed the problem and the consensus was that the "smart line" was used to tell the blower motherboard what wattage the power supply was capable of delivering so that it would not allow you to exceed that capacity by connecting too many loads.

Dude

[OMyMyOHellYes]

We have previously discussed the problem and the consensus was that the "smart line" was used to tell the blower motherboard what wattage the power supply was capable of delivering so that it would not allow you to exceed that capacity by connecting too many loads.

Dude

If you're running a battery instead of the manufacturer's power supply, how does that play?

My considered consensus is that it is just the manufacturers padding their pockets at the expense of users. I mean we went how many generations of machines without it?

Follow the money.

OMMOHY

[Marthajoy7]

Remember the days of the texas Instruments home computer. they patented a memory that the memory chip generated interrupt instead o the cpu. They figured with this being used on their computers that only they could sell games for them. Another company found a way around the patient by using multiple chips. They tried suing and lost in court. The next day they dropped out of the market.