My battery backup setup

[OMyMyOHellYes]

I will also post this in its own post, but as this one often gets kicked around, I wanted to put it here too.

Much todo has been made regarding the Deltran Battery Tender chargers from time to time here for maintaining backup batteries for CPAP use. Still top flite, but I have also added the NOCO Genius chargers to my lineup. The four spare 35 AH batteries in the closet are now on a NOCO G4 charging bank with four separate charging circuits. Not the fastest as it is only a 4.4 A charger (divided by 4 if all four slots are on), but fast is not the purpose. It is to keep all four of them charged, all the time, with no intervention required from me.

Still have and use my 6 A Battery Tender for when I want to push the charging rate up (like a partially depleted car battery). No longer driving the truck daily - maybe every week or two - and I intend to mount a NOCO 2D under the hood so as to, in the words of Ron Popiel, RONCO founder, "Set it and Forget IT!" to keep that battery topped off when not in use (don't want to do a complete cutoff as I want things like the radio and clock and electric door locks to continue working).

Anyhow, just thought I'd offer up another option if anyone is considering a new charger.

[Fats Drywaller]

Good thread, fun stuff.  Here are a few non-technical contributions:

Resmed versus others:  I want to gripe about the Resmed-bashing that has been inspired by the connector conspiracy.  ("I'd like to complain about people who hold things up by complaining about people complaining.")  There are far more important things here than which manufacturers let you use a 12V battery without a converter.  Shouldn't we decide which machine we want to use based on the internal features and performance in objective comparisons of the various makes & models, rather than whether we have to buy another cable (or maybe build one)?  Deciding based on the cable is absurd.  Elsewhere, I mentioned all the good points I could think of about the De Vilbiss DV54, then I said "But none of these has anything to do with CPAP!  What is wrong with this picture?"  Judged as a CPAP/APAP machine rather than a UPS, the DV54 turns out to be mediocre.

In my experience, Resmed does many things right except for (speaking of Resmed-bashing) the vile P10 mask (I fart in its general direction) and the lack of an on/off switch for the cellular modem.  The Air10 machine itself, either Airsense or Aircurve depending on your needs, is ab fab.  So anyone who is shopping around and deciding what to buy shouldn't pay any attention to complaints about the special cable.  Buying that converter is a little bite, not a big one.  Or if you want to make a converter, that's great.  If you already have an A10 or an S9, there's no reason to get a different machine unless you need to minimize weight for backpacking.  As for dropping Resmed and buying some other brand just because of the connector conspiracy, as someone mentioned way back in the thread, that's even more absurd.  Anyone who is willing to give up all the benefits of the excellent Resmed firmware for that trivial reason needs a check-up from the neck up.

Off-the-shelf DC-DC converters for Resmed:  For anyone who doesn't want to do the home-brewed stuff, the Battery Power Solutions DC-DC converter, which I think has BPS part number FBA_BPSC-24V-RES (at least that's what it's called on Amazon), around US$70, is more versatile than the Resmed 37297, which is specific to the A10: the BPS has more options for cables & connectors, not just a cigar-lighter plug on one end and the Resmed DC plug on the other.  In addition to the A10 & S9, it can be used to power other devices, not only CPAP machines, that take 24VDC without the Resmed Masonic handshake.  As was mentioned upthread, the Resmed converter can use either 12V or 24V as input, and the same is true of the BPS, in case you have a 24V power source and you want to add the Resmed handshake to that.

Off-the-shelf DC-DC converters for others:  For any device that needs 24V without the Resmed thang, a slightly less expensive 12-to-24 converter is the Bixpower DD90M-24V, US$50, which the manufacturer claims is very efficient, 96%.  One reason I mention it is that the Philips Dreamstation Go wants 24V but its proprietary battery costs about US$300, ouch!, for a puny 62 watt-hours (one night's worth).

Li-ion batteries:  There have been more lithium-ion battery products, at least (I don't know about SLA/AGM, etc.), introduced in the last few years, so it's a good idea to do a lot of window-shopping before buying anything expensive.  A while ago I started a thread in the Other Product Reviews forum about a Gissaral 130-Wh Li-ion battery, and that includes some more general information, although it's about backpacking rather than UPS setups at home where the weight doesn't matter.  I don't recommend the Gissaral for reasons mentioned there, but some similar products look very good, including one from Renogy (266 Wh) and one from XTPower (195 Wh).  These days, you should be able to get three nights of unheated CPAP use from a high-capacity Li-ion battery before recharging, if you don't mind that the battery weighs about 3 pounds.

So there's no need to settle for the lame Li-ion batteries that are sold specifically for CPAP: the ones branded Resmed, Philips, BPS, Medistrom, Bixpower, and Powermod.  Each of those has a capacity under 100 Wh, is good for only one night of CPAP, and costs between two and eight times one of the alternatives I've mentioned.  However, if you have money to burn and you'll be using the thing as part of a UPS setup at home where the max duration of the "power outrage" (sic) will be 8 hours, those CPAP-intended products should work fine (with the machine's heaters switched off).

With a full-size machine and an arbitrary third-party battery, be sure to plan for the startup current, probably 3.75A or thereabouts.

[OMyMyOHellYes]

Resmed versus others:  I want to gripe about the Resmed-bashing that has been inspired by the connector conspiracy.  ("I'd like to complain about people who hold things up by complaining about people complaining.")  There are far more important things here than which manufacturers let you use a 12V battery without a converter.  Shouldn't we decide which machine we want to use based on the internal features and performance in objective comparisons of the various makes & models, rather than whether we have to buy another cable (or maybe build one)?  Deciding based on the cable is absurd.  Elsewhere, I mentioned all the good points I could think of about the De Vilbiss DV54, then I said "But none of these has anything to do with CPAP!  What is wrong with this picture?"  Judged as a CPAP/APAP machine rather than a UPS, the DV54 turns out to be mediocre.

In my experience, Resmed does many things right except for (speaking of Resmed-bashing) the vile P10 mask (I fart in its general direction) and the lack of an on/off switch for the cellular modem.  The Air10 machine itself, either Airsense or Aircurve depending on your needs, is ab fab.  So anyone who is shopping around and deciding what to buy shouldn't pay any attention to complaints about the special cable.  Buying that converter is a little bite, not a big one.  Or if you want to make a converter, that's great.  If you already have an A10 or an S9, there's no reason to get a different machine unless you need to minimize weight for backpacking.  As for dropping Resmed and buying some other brand just because of the connector conspiracy, as someone mentioned way back in the thread, that's even more absurd.  Anyone who is willing to give up all the benefits of the excellent Resmed firmware for that trivial reason needs a check-up from the neck up.

Oh, that make me laugh.

"benefits of the excellent Resmed firmware".  Bug not feature.

Power supply capability is for some every bit as important as those silly data reporting features that some folks seem to consider necessary.  Or heated humidification.

I have two S9 Autoset units gathering dust.  Will likely never see the dark of the nightstand.  My DeVillbiss gets far more use than the RumpMeds, er, ResMeds.

[Fats Drywaller]

Power supply capability is for some every bit as important as those silly data reporting features that some folks seem to consider necessary.  Or heated humidification.

I didn't mean data reporting or heated humidification, but the better sleep that I get when using the Air10 compared to, for instance, the DV54.  It's obvious that a lot of development effort has gone into the Resmed firmware over the years, and the result for the patient is better breathing, lower AHIs, etc.  Although Resmed has made a few mistakes with other things, they got the basic machine right.  Very much so.  Well, I guess that shouldn't be surprising; this is the tenth generation of it, so they've had a lot of practice.

My DeVillbiss gets far more use than the RumpMeds, er, ResMeds.

Just as long as you don't mind that its firmware is from 2015 and will never have its various bugs & misfeatures fixed.  To me, the DV5x series basically works OK and does the job.  I can use it, and I give it a passing grade.  But it's not as restful an experience as the Resmed.  It's sort of analogous to sleeping in some random motel room compared to sleeping at home: which one is more comfortable?

Anyroad, De Vilbiss is an also-ran, and the big competition has traditionally been between Resmed and Philips (or, formerly, the pre-Philips Respironics).  And, thanks to information obtained from the data reporting among other things, we've seen how that one has gone lately.  What machine gets recommended to newbies here, over and over?  And why? It's not because of the power supply.

[OMyMyOHellYes]

 What machine gets recommended to newbies here, over and over?  And why?  It's not because of the power supply.

"What machine gets recommended to newbies here, over and over?  And why? "

Herd mentality.  And repeating something over and over and over and over until some folks think it is a fact.  And rooting for the home team - most oflks get what they get and are not going to adventure out and try others, but they become experts in the superiority of their own choice.  See also "fanboy".  BTW, I drive GM and foreign cars.  Ford products suck.

[Technopauper]

I managed to get a cheap Freedom CPAP battery on local gumtree equivalent but it didn't come with with the convertor for Resmed Aircurve - am I right in saying that the battery is 24v and the Aircurve is 12v ? is there any cheaper way of connecting than the Freedom 24V convertor as its about CAD100 ?

Rob

[Sleepster]

I managed to get a cheap Freedom CPAP battery on local gumtree equivalent but it didn't come with with the convertor for Resmed Aircurve - am I right in saying that the battery is 24v and the Aircurve is 12v ?

The ResMed AirCurve as well as all other ResMed machines run on 24 volts DC.

is there any cheaper way of connecting than the Freedom 24V convertor as its about CAD100 ?

If you're handy with electronics you can probably get it to work. There's a third conductor, IIRC, that sends a proprietary signal. There's a thread somewhere on how to defeat this, with instructions on how to build the circuit.

[gzimmer]

I've read this whole tread with interest as I live with solar power and would like to run my ResMed AirSense 10 direct from 24V DC rather than running my large 240V AC inverter continuously.

Firstly a comment on the non-standard connector:

Any engineer who has worked in an EMC compliance lab will tell you of the extreme testing requirements for automotive products (eg 12V), and even more so for Medical equipment.

There are many requirements, but the big one is the "Load Dump Test" (please google it).

The problem is that when a vehicle with a dead battery is jump started, and the jumper leads are removed, the alternator will put out a huge voltage spike as it tries to adjust to the different load.

The test for this is a large bank of electrolytic capacitors which are charged to 200V and then dumped across the test device.
This test is sufficient to completely destroy many nominally 12V products. For example, when an unprotected auto instrument cluster is tested, the load dump test will blow every globe in the cluster. They go off like flash bulbs. Novice product engineers hate the Load Dump Test!

There are other tests: Many 4WD's and trucks use 24 Volt batteries, so the device must withstand a jumper to 24V, and also 24 Volt applied in reverse.

This means that any automotive product will have to be incredibly well engineered to survive to basis tests, and if it's a Medical device the tests are even stricter.

So all this means that any approved medical device approved for automotive use has to meet the Load Dump test, or be fitted with a non-standard connector so it cannot be easily connected to a 12 or 24 Volt battery.

A comment on the third wire resistor:

It is very common in the industry for a signalling method to be used so that the device can communicate with it's power supply.

There are lots of reasons, the main one being so the device can tell if it is plugged into a simple charger or something more complicated.

Another reason is so the device can sense just how much current it can pull from the supply. A common example is the signalling method used with USB chargers (do a google search on "Introduction to USB Power Delivery).

I hope this clears up some of the rather silly arguments earlier in this thread.

[gzimmer]

i meant to add that the plug is a fairly common one, used on Dell and HP laptops.

Do a search on "Philmore 274"

or "Barrel plug 7.4 x 5.0mm x 0.6 Pin"

or search ebay for "7.4x5.0mm Power Plug HP Dell Laptop"

[gzimmer]

Oh, and one other thing:

To be compliant with the medical standards, the power connector would need to be waterproof.

If you look at the one on the A10 you'll see that it has a rubber "O" ring.

I doubt that a normal cheap connector would meet the latest standards.