RE: Power outage
(12-12-2018, 07:21 AM)OMyMyOHellYes Wrote: You don't gain anything notable by going to a 24 V power supply or battery if it's going through the Resmed DC-DC converter. The step up is not that substantial. 12 V stuff is much more readily available both locally, wherever you may be, and even on the the world wide internwebs. Cars use 12 v; airplanes use 24 and there are probably more cars than airplanes out there. That flexibility is probably worth way more than what would be gained with 24 V.
dc-dc converters are more efficient when the input voltage is closest to the output voltage but you're right in that the difference wouldn't amount to much. I would use 12v to feed the Resmed converter too unless I found a mega sale on batteries. Well, but then I would just parallel them to get longer runtimes.
Regarding 12v for automobiles, it won't be the standard for long. 48v systems are starting to work their way into the auto industry. We should start seeing 48v car systems next year give or take. Of course it will take years but the push will be there.
(12-12-2018, 09:35 AM)Fats Drywaller Wrote: In case you hadn't been taking this into account (and this is one reason OMMOHY said there's nothing to be gained by using 24V instead of 12V), the Resmed DC-DC converter or its equivalent from Battery Power Solutions or any other third party (Medistrom, Bixpower, Powermod) also provides the Resmed secret Masonic handshake on a third pin as an input to the A10 or S9 power jack. So, unfortunately, you can't plug just any 24V supply into one of those Resmed machines and have it work; the machine will play dead.
...
BTW, the maximum current draw is probably estimated assuming that the humidifier heater and heated hose will be used. ISTR from other posts here that without the heaters, the motor startup current is less than 3.75A and the usual consumption after that is 1A or less. (See the Resmed Battery Guide for the full story.)
Yup, you're right about the signal. I was referring to the 24v PWRgate version not a different ResMed adapter. You still need ResMed's adapter (or one of the others that you mentioned) no matter what power you feed it. Going by Rockpal's specs, 3.75a would be enough to overload the Rockpal at 24v. The ResMed adapter would draw more at 12v and Rockpal's limit at 12v is 4a.
ResMed specs for the converter
Input: 12v/24v 13/6.5A
Output: 24v 3.75A
peak power consumption
A10 - 106W
S9 - 110W
typical power consumption
A10 - 51W
S9 - 70W
Real world, would you ever see that? I doubt it. However, I would not rely on the Rockpal to always work when it would be pushed close to its max rating. Not for the coin you shell out for it anyway.
RE: Power outage
(12-12-2018, 07:33 PM)AlanE Wrote: Yup, you're right about the signal. I was referring to the 24v PWRgate version not a different ResMed adapter. You still need ResMed's adapter (or one of the others that you mentioned) no matter what power you feed it.
Yes. Sorry to confuse the issue earlier. Your last sentence there is all I meant: the adapter has to be at the end of the chain, regardless.
Also, about the power requirements, I was stupidly forgetting that if the objective is to have automatic failover and uninterrupted sleep, then the heaters have to be included in the calculations.
So anyway, never mind, and "As you were!" and all that good stuff.
The fancy auto-failover configuration with the hefty batteries and the PWRgate is something I would like to have, just sort of casually wishing, but can't afford ... so for me it's sufficient to have a Li-ion battery pack charged and ready to be manually swapped in (and at that point it'd be necessary to switch off the heater).
12-13-2018, 05:36 AM
(This post was last modified: 12-13-2018, 07:27 AM by OMyMyOHellYes.)
RE: Power outage
(12-13-2018, 05:29 AM)Fats Drywaller Wrote: The fancy auto-failover configuration with the hefty batteries and the PWRgate is something I would like to have, just sort of casually wishing, but can't afford ... so for me it's sufficient to have a Li-ion battery pack charged and ready to be manually swapped in (and at that point it'd be necessary to switch off the heater).
For the longest time, I just kept a 35 AH 12V SLA on a Deltran battery tender and if the pwr dropped, I would just get up, unplug the Respironics power brick, lug the battery out of the closet, plug it in to the CPAP, turn the humogrifier off and go back to sleep. Slight inconvenience, but relatively cheap and effective. Nothing wrong with that.
Did that for probably four years before I put together the money to upgrade (as I like tinkering with electronics, for me the upgrade was as much of a fun project as it was a utilitarian exercise). But in those four years, I probably only had to do the midnight express change over a couple of times. Perfectly fine.
There. I said it.
OMMOHY
Contrarian in Residence
RE: Power outage
That will work, assuming someone wasn't as lazy as me. lol I would just get P.O.'d, get up to get a drink of water, then have to pee, then watch tv (assuming power was back on by then), then go on the Apneaboard and surf power failure options.
12-13-2018, 04:19 PM
(This post was last modified: 12-13-2018, 04:19 PM by AlanE.)
RE: Power outage
(12-13-2018, 05:36 AM)OMyMyOHellYes Wrote: I put together the money to upgrade (as I like tinkering with electronics, for me the upgrade was as much of a fun project as it was a utilitarian exercise).
Have any notes you'd like to share? Always looking for an excuse to buy parts.
Lt. Colonel Bill Kilgore's brother's friend's third wife's cousin's electronics professor Wrote:You know, one time we soldered, for twelve hours. When it was all over I walked up. We didn't find one of 'em, not one stinkin' soldering iron. But the smell! You know - that burning flux smell... the whole lab! Smelled like... victory.
RE: Power outage
Oh, yeah. It's been out there several times.
35 AH SLA battery, West Mountain SuperPWRgate 400, Astron power supply, wires and Anderson PowerPole connectors.
I think they made one of the last ones a wiki, so Ill just point folks to that rather than burning up lots of electrons again.
http://www.apneaboard.com/wiki/index.php..._Solutions
There. I said it.
OMMOHY
Contrarian in Residence
12-16-2018, 09:47 PM
(This post was last modified: 12-16-2018, 09:51 PM by AlanE.)
RE: Power outage
Thanks. I suppose I could have just searched.  
These last two nights in a row saw my power fail for just long enough to shut down everything. So this renewed my interest in backup power.
BTW, on an unrelated note, Philips Hue lights now have an update to shut the lights off when the power returns from a failure. Previously they just stayed on. Wonderful at 2am to wake up to.
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