Battery and ResMed revisited

Hi Gang,
I just picked up a steal of a battery supply at SamsClub.com (no appropriate link on-line) - it was $45, included a dc jack, 2 ac outlets (modified sine wave) and some other goodies. very bulky, it says good for camping - i woudln't want to carry it around -- but i do want it around for when i lose power (usually 2 big storms per summer)
i read (from links on this site, and then resmed) about actually being able to use modified sine wave for the machine, but not the humidifier (i have the s8 autoset ii with the h4i) - my questions:
1) does anyone know if you can keep the humidifier assembled but switched off - so passive?
2) resmed appears to say modified sine wave is fine but not for the humidifer (which suprised me - i thought the machine would lose power)
3) i thought about buying a sine wave inverter (like on cpap.com) and plugging it into my new battery backup (and ignoring the built in inverter)
4) i thought about skipping the inverter and buying the $80 proprietary s8 dc plug - it is supposed to be more efficient
5) doing the math, it makes more sense (to me) to spend $109 or so for a multipurpose inverter, than a proprietary $80 adapter - whether or not i want to run the humidifier
any thoughts or suggestions appreciated! Thanks!

bumptety umpety bump

Gary,
I'm a 2 week Newbie, and have the same machine and humidifier. Needless to say, I am very uneducated regarding what I need, and living on Cape Cod where we are always ready for power outages from Nor'easters, etc. I am very concerned about not being able to use my CPAP.
Please tell me what the name of the battery supply package is, maybe I can find one somewhere else, as I'm not a member of SamsClub. (Or maybe I can find an "uncle" who has a membership!)
Thank you, and please keep us updated if you purchase a multipurpose inverter for $109 and what that product name is as well.

Good luck

Violet - i have now 3 "12 volt dc" doohickeys at home - one was for my computerized telescope, then i bought a bigger one that also has car jumper cables, and now finally "the behemoth" i picked up last night (no booster cables, but yes to a radio, flashlight, etc.)
the gist is you essentially have some sort of 12 volt sealed battery - whether it is a motorcycle battery or a scooter battery i have no idea - and the battery is in a "package" - my prior ones merely had 12 volt dc lighter socket receptacles - turning them into mini cars - you know, like when you plug in a car vaccum or air pump or whatever into the cigarette lighter? the one i bought last night also has, built in, a modified sine wave inverter - meaning it will power SOME home electronics using a regular 2 or 3 prong outlet - needless to say this is not for keeping your lobster fresh in the refigerator - it would probalby melt the thing - but it should be fine to power a notebook computer, MAYBE a small tv, etc.
then there are bigger ones for campers, or dedicated purposes.
the big choices that i see for us are:
1) get something on the idea i did, i.e. a 12 volt battery, and the resmed 12 volt adapter, or
2) get a battery and a no-name adapter (i'm a little nervous about this one) - normally i would, but i'm scared of damaging the machine,
3) get a battery and use a modified sine wave inverter (like what's built into my $45 purchase from last night, or
4) get a battery and get a pure sine wave inverter (which should also power the humidifier) - a pure sine wave inverter is available from cpap.com - so then you just need a 12v battery - you can get that at sears or walmart or any other large (or not even large) store - the idea is a portable car cigarette lighter.
i do believe a battery and the 12 volt adapter (cpap.com has them) is a more efficient way to go -- but it is proprietary - so i can't use the adapter with anything else - if i get the inverter it will be less efficient (i'm only worried about 8 hours of power) so i'll see about trying out the built in inverter (if it's strong enough) with a spare machine to see how long it can power - not sure if it will be accurate but it should give some guidance
hope this helped, and i welcome thoughts from the pros!!!!!

Thanks Gary, I'll print this out and carry it with me for purchasing. I think it was a 12 volt battery I bought recently for my JD rider mower, I'll have to check. Hopefully, I can pull this together sooner rather than later, will keep you updated.

Violet - good luck - though you can use a "bare" battery and hook wires to the terminals, for what you want (presumably in your bedroom) i'd spend the roughly $40 or so on some sort of DC pack - and then plug into it - you don't want bare terminals hanging around your bedroom - maybe okay for the garage.
this is on the idea of what i'm talking about - there are bigger and smaller units, and you're not stuck with only one brand:
http://www.blackanddecker.com/ProductGu ... ctID=15589
Hope this helps!

Gary,

I can't answer your exact question about the humidifier because I don't own a ResMed, but I've run my RemStar with the humidifier in place, power not connected most of the summer with no problems. I believe you only need pure sine wave for the humidifier.

Violet,

Like Gary I have reservations about using a bare battery inside. I own the Black and Decker 400. My husband picked it up at Walmart for $80.00. If you plug your CPAP into the AC outlet you will get about a night and a half (depending on your pressure) Purchased the DC inverter from cpap.com ($25 about)and can get 5 nights but remember, draining the battery completely will cause it to lose efficiency, so I don't advise it, I drained it only to test how far I could push the thing, now it gets pluged in as soon as I can after I've used it.

Be forewarned, If you have Resmed.s, they are power picky, That 's why the Resmed power cord costs more than other brands... Plan wisely. Doorstops are costly. Jim

Goofproof wrote:Be forewarned, If you have Resmed.s, they are power picky, That 's why the Resmed power cord costs more than other brands... Plan wisely. Doorstops are costly. Jim

Jim, valid point - until i read the resmed white paper earlier today, i thought i could not use modified sine wave because of the motor - or that the humidifier pulled too much power. i was suprrised that the whie paper from resmed allowed modified sine wave.
i personally believe the 12v resmed dc adapter will give "cleaner" power but i guess the circuitry can compensate for modified - strange that the humidifer can't though...if i have a power failure, i'll have to remember to shut the humidifier, though i'll likely leave it connected - then again, i'm so neurotic i'll probably disconnect the humidifier...

Goofproof wrote:Be forewarned, If you have Resmed.s, they are power picky

No.

The S8 flow generators will blow an internal fuse if you put reversed polarity on the input, but otherwise the flow generators are not more or less "picky" about DC power that other brands.

dsm showed the connections for running an S8 directly off a car "cigrarette lighter" outlet on CPAPtalk years back!

Goofproof wrote:That 's why the Resmed power cord costs more than other brands...

The Resmed DC-12 provides a number of things which are there to basically ensure that a user who doesn't understand anything much about battery electrical systems can use an S8 in a wide range of circumstances with good results.... that's why it costs more than other brands

The DC-12 provides for:

• operation from (nominal) 12V and 24V DC power systems, so it useable from both "automobile" type battery systems, and "truck" type battery systems
• complete isolation between the input and output circuit
• filtering out of electrical "noise" from the input side
• preventing a battery from becoming fully discharged

Cheers,

Bill

GaryGarland wrote:1) does anyone know if you can keep the humidifier assembled but switched off - so passive?

Yes, but you should definitely go into the setting menus and make sure the humidifier is deselected if you are thinking of running with an H3i/H4i attached to an S8, when the S8 is running of "modified sine wave" AC power, as a safeguard against accidently turning the humdifier on.

GaryGarland wrote:2) resmed appears to say modified sine wave is fine but not for the humidifer (which suprised me - i thought the machine would lose power)

The S8 flow generator is like most electronic systems now a days and it fairly tolerant of input power voltages and waveforms.

The humdifier is basically a phase controlled electrical heating system and needs true sine wave power to operate correctly.

GaryGarland wrote:5) doing the math, it makes more sense (to me) to spend $109 or so for a multipurpose inverter, than a proprietary $80 adapter

There nothing "proprietory" per se in the DC-12... it contain fairly standard DC power electronics. The "special" aspect of it is that it combines a number of functions which aren't normally grouped togther in one unit, to particularly address the issue of fool-proofing (as far as resonably possible) the use of S8s from battery systems.

For a CPAP user, not being able to run a flow generator from a battery supply is something more than just an inconvenience, so battery power solutions that work for running a TV or computer off a battery which just "mostly" work are not going to be satisfactory.

Anyway, as the old saying goes.... you pays yer money and you makes yer choice!

Cheers,

Bill

billbolton wrote:

Goofproof wrote:Be forewarned, If you have Resmed.s, they are power picky

No.

The S8 flow generators will blow an internal fuse if you put reversed polarity on the input, but otherwise the flow generators are not more or less "picky" about DC power that other brands.

dsm showed the connections for running an S8 directly off a car "cigrarette lighter" outlet on CPAPtalk years back!

Goofproof wrote:That 's why the Resmed power cord costs more than other brands...

The Resmed DC-12 provides a number of things which are there to basically ensure that a user who doesn't understand anything much about battery electrical systems can use an S8 in a wide range of circumstances with good results.... that's why it costs more than other brands

The DC-12 provides for:

• operation from (nominal) 12V and 24V DC power systems, so it useable from both "automobile" type battery systems, and "truck" type battery systems
• complete isolation between the input and output circuit
• filtering out of electrical "noise" from the input side
• preventing a battery from becoming fully discharged

Cheers,

Bill

I thought that besides [*]preventing a battery from becoming fully discharged[/list], it was as the voltage drops the current required to run goes higher, and can cause problems from that. Having a the +/_ backwards from what most the world uses doesn't make much sense either. Maybe it has something to do with the water going down the drain in reverse at the manufacturing plant. Jim

Goofproof wrote:Having a the +/_ backwards from what most the world uses doesn't make much sense either.

The reason that all the "universal" plug packs come with polarity reversible connection tips is that there is no "standard" that most of the world uses.

Its also why just about all electronic equipment with a 12V input socket puts a symbol near the power input socket that shows which polarity convention the socket is wired to.

So its just plain silly saying that Resmed kit is wired backwards.

I'm down in my Cave, with 3 computers in it and a dozen power bricks, all over the room running 6 different 12 volt D/C devices, all + (POS) center connectors, and I am bothered because one kind isn't 3.5 mm. I do wish they would make a standard, or maybe color code plugs, for us almost blind people with poor room lighting.

for whatever it's worth, i ended up buying a pure sine wave generator on ebay last night - i am hesitant to hook the s8 directly to the 12v even with a reverse tip, though i think it would be alright. i may disconnect the humidifer altogether and then try modified sign wave from my supply, and then compare to pure sine wave -- if i can get 8 hours with pure sine wave and humidifer it would be a home run - as my buddy said, the storms are usually in the summer, so if i don't have air conditioning running i won't be doing much sleep anyway!
when my DME told me the machine was roughly $1,300 without insurance, i was a lot more nervous than when i picked up a spare unit for $300...