ResMed S9 and external power/UPS supply

idamtnboy wrote:

DreamDiver wrote: The problem with the S9 is that without a 12V DC to 90V DC converter, I'm concerned my marine battery wouldn't last three days on a single charge for the S9 because I'd have to first connect an inverter to my battery and then plug the S9 into the inverter.

I think you mean 12V DC to 24V DC. 90 is the wattage of the power supply.

I can see the concern about overall efficiency of inverter + power supply but I wonder how that compares in reality with the efficiency of a DC-DC inverter. Is there such a significant difference that the DC-DC unit is much more desirable? I have a hard time thinking how the DC-DC could be much more efficient since the same basic steps in the single unit and the combined separate units would have to be much the same. The last I knew the only way to step up voltage is with current passing through a transformer or inductor coil, and that's probably the most inefficient part of the process.

You're right about the conversion factor! Thanks. It's not so much that one might be more efficient than the other. With my M-Series Pro, I only have to go from battery to converter to machine. With the S9, I have two steps: battery to inverter, inverter to ac adapter. DC to AC, AC to DC again. It's more efficient to do it just once: DC to DC.

I'm considering printing out these pages and the clinical manual and giving them both to the guy at Batteries Plus to see what he comes up with.

Me putting out $600 buck will probable insure Resmed will come out with the solution soon afterward.

I think all we really need to be able to come up with a good solution is a source for a power plug that will fit into the S9 socket. I found today on the 'net a battery charger specifically made to keep two 12 volt batteries, connected in series, properly charged. The charger has sufficient capacity that it could be connected to the batteries and will provide power adequate to run the S9, but will also keep the batteries charged with a trickle charge. Then the batteries could be connected directly to the S9. You would have to have two 12 volt batteries connected in series to give 24 volts, but each would only have to be half as big as a single 12 volt battery, or actually even a little smaller since a direct battery connection to the S9 is the most efficient. The S9 would always be connected to a power source even when the house power goes out. You would avoid the losses caused by a 12 to 24 volt DC inverter, or the inverter/S9 adapter setup.

Anyone have any idea where we can get a plug that will fit in the S9? I think it may be nothing more than a 3 pin version of a 6, 7, or 8 pin DIN connector configuration. Another possibility, but not the most desirable, is to cut the the plug off the S9 power adapter and reconnect it to the adapter with a readily available male/female connector pair. Then a matching connector would be connected to the lead from the battery and the S9 connector plugged into it. The same S9 plug would be used to power the S9 from either the house power adapter or the batteries.

Power outages are not a concern for me but I would be willing to help someone fix up this kind of configuration. My unit is on rent from the DME so they still own it. I would probably have a very upset DME supplier on my hands if they found out I cut the cord on the power adapter!

jazzer4 wrote:I've been reading on here about back up power for a year and still have not initiated anything because it's all so complicated.

I wish Resmed would just work on this. Come on Resmed step up to the plate.....make it easy. (for dummies like me)

Yeah-that'll be the day. Even my S8's humidifier won't work without pure sine wave power on 12V. And my DME was cluless about it until I proved it to him.
Sorry, rant off.

I am curious what the small pin does? I bet there is something exclusive to the S-9 that must have a signal of some sort to operate. Mine has 24.16 volts at the 2 large pins and 3.26 volts on the small one. 3 volts is a common voltage for electronics, but a regulator could have been be put inside the S-9 to do that. They don't want anyone to be able to power it up without buying the power supply from them. john

jlk wrote:I am curious what the small pin does? I bet there is something exclusive to the S-9 that must have a signal of some sort to operate. Mine has 24.16 volts at the 2 large pins and 3.26 volts on the small one. 3 volts is a common voltage for electronics, but a regulator could have been be put inside the S-9 to do that. They don't want anyone to be able to power it up without buying the power supply from them. john

I was wondering about that this morning and was thinking I should have said something about that in my post above. It very well could be that third pin is for some sort of feedback circuitry that makes it so the S9 must have a proprietary Resmed power source connected to run.

You have to be cautious about what you measure on the output pins of modern power adapters. My experience has been sometimes the no load voltages are significantly different than with loads connected. Caused by electronic idiosyncrasies I guess. I'm not an electronics tech or engineer so when it comes something like this I'm flailing in the dark!

Keep thinking boys. You guys can figure this out. I'll keep posting to bump this post. Possibly others will jump in and help too.

Solve the whole problem, not just the CPAP.

Whole house Natural Gas generator:
http://www.kohlerpower.com/residential/ ... num=347261

14kW unit, transfer switch auto senses grid power failure, and switches on to provide power to the whole house, I mean everything you would normally use in your house.

Because my house already uses NG, this seemed to be the obvious choice. NG is clean burning, and supply is consistant, even in a power failure.

So if the power goes out, the generator kicks in (up and running in under 20 seconds) and all is normal again.

When power is restored by the supply grid, the unit turns itself off.

TOken wrote:Solve the whole problem, not just the CPAP.

Whole house Natural Gas generator:

Good solution providing --------------------

1. You can afford it, and
2. You suffer enough power outages to justify it, or
3. Power outages result in such a dire consequence that cost or frequency is a secondary factor, and
4. Cost effective alternatives are not available.

But, and this is a BIG BUT for some, you can't easily take your 14 kw unit generator with you when you go camping!!

idamtnboy wrote:

TOken wrote:Solve the whole problem, not just the CPAP.

Whole house Natural Gas generator:

Good solution providing --------------------

1. You can afford it, and
2. You suffer enough power outages to justify it, or
3. Power outages result in such a dire consequence that cost or frequency is a secondary factor, and
4. Cost effective alternatives are not available.

But, and this is a BIG BUT for some, you can't easily take your 14 kw unit generator with you when you go camping!!

Valid points... Now this "Camping" thing you speak of.... That's like a Holiday Inn right??? LOL!

TOken wrote:Valid points... Now this "Camping" thing you speak of.... That's like a Holiday Inn right??? LOL!

I know some people for whom a Motel 6 is, or was, in the same category as camping!

I did check into a whole house generator.
$14 grand for my house.
Not an option right now.

idamtnboy wrote:

TOken wrote:Valid points... Now this "Camping" thing you speak of.... That's like a Holiday Inn right??? LOL!

I know some people for whom a Motel 6 is, or was, in the same category as camping!

Does this count as camping? Zion 2006

Is that a converted horse trailer?

I purchased a DC power pack (for another purpose). I noticed they have some nifty AC Power packs as well.

I wonder if they would be more suitable than a UPS designed for coputers and the like?

http://www.powerportstore.com/power.htm ... 20SUPPLIES

Mort