[Equipment] Resmed Autosense - No Electricity Scare

[Zainabpb]

Hi there 

They have just implemented Load-shedding in South Africa ( Load shedding is when they cut the electricity due to overload in Power supply) This can happen at any given time for up to 4 hours where there is no electricity. Needless to say this will not be good for my CPAP that is reliant on power. What to do? What do I need to get my CPAP off the grid and keep it running when the power goes off. I'm already stressing that this will happen during the night.

[Fats Drywaller]

It's a big topic.  If it has a short answer, I don't know what that is, other than "Try an off-the-shelf UPS", but that has various problems ... mainly, it doesn't make any sense to convert battery power to higher-voltage AC using an inverter and then have the CPAP machine's power brick convert that back to the same low-voltage DC that you started with. That's wasteful.  There are many discussion threads here on AB about using a UPS with a CPAP machine or, a better idea, putting together a home-brewed setup with batteries & cables that you can switch to manually when the power goes out.  For starters, here are some search terms you can give to Google if you want to read up on it:

site:apneaboard.com intitle:ups

And:

site:apneaboard.com intitle:battery OR intitle:batteries

If there is a recipe for putting together a good configuration from off-the-shelf components, it's probably somewhere in one of those threads.

Let's ignore the UPS method for the moment. To oversimplify, there are two kinds of batteries: big & heavy & expensive, or else small & lightweight & less expensive, which this year are lithium-ion.  The small & lightweight ones will usually give you only one night of CPAP use (somewhere around 100 watt-hours) before needing to be recharged from AC power or from a running motor vehicle, but it is possible to buy one with a capacity sufficient for two nights (around 200 watt-hours).  Then you'll need some cables with particular connector types and, for a Resmed machine, a converter box that goes from 12V to 24V and provides the secret Resmed handshake.  That last component can be either a Resmed part or one from Battery Power Solutions.  Those are the only two that I know of that are available separately, not packaged with an overpriced battery.

But if you have money to burn and you don't want to put together your own home-brewed setup for power backup, you can buy one of those overpriced off-the-shelf "solutions" from BPS or Medistrom or Bixpower or even from Resmed (not recommended because that one is priced around US$700).  Those all use the small, lightweight lithium-ion batteries, which aren't as good in a lot of ways as the larger, heavier ones.  Those lightweight products are intended for use when traveling and camping, but they are also appropriate for power backup during an outage lasting only several hours. So that's one way.

If you do consider a UPS (DC to AC to DC to CPAP machine), remember that its batteries also wear out after maybe a couple of years and need to be replaced at great expense.  Most of the cost of a UPS is in the batteries.

[Fats Drywaller]

I forgot to say that if I had to choose one of the off-the-shelf packages including the battery (good for up to 8 hours of CPAP use) and a Resmed-compatible converter cable for the A10, it would be the Battery Power Solutions "Freedom". I haven't chosen it so far because I'm a cheapskate and I prefer to roll my own, but that does look like quite a good product on paper. The retail price at the moment is somewhere around US$330, which is about half of what Resmed charges for its equivalent "Power Station II".

So, to contradict what I said before, that is one possible short answer of the "Buy this product" type.

[Zainabpb]

Thank you for the feedback. I understood half of what you said lol. But it seems I have to go for he off the shelve route as I don't have any knowledge of brewing my own. O don't however have that kind of money laying around as I'm only 3 months on CPAP and paid for my CPAP out of my pocket, needless to say I'm broke. But will te read your post again when I have the money to buy one....Thanks ?

[Fats Drywaller]

Oh, OK, here is a good one, thanks to OMMOHY for that and to Simon H for the thread bump just now that called attention to it.

But that is more expensive than the lithium-ion short-term backup and much more trouble to build. So for CPAP use during mere load-shedding, I think the smaller battery pack is the way to go.

[Fats Drywaller]

O don't however have that kind of money laying around as I'm only 3 months on CPAP and paid for my CPAP out of my pocket,  needless to say I'm broke. But will te read your post again when I have the money to buy one....Thanks  ?

You're welcome, and thanks to the actual pioneers here who have figured out the ways to do it, but yes, the expense is always a problem, one way or another.

The cheapest way I've found so far is described in this thread (also somewhat technical) in the "Other Product Reviews" forum: US$80 for a battery pack plus $70 for a BPS Resmed-compatible converter cable, total US$150. That gives about 8 hours of CPAP use before needing a recharge.

[Zainabpb]

 Looks a bit more affordable. Now for the hunt in South Africa for these gadgets.

[Fats Drywaller]

If you do it yourself with those components, you have to be careful to get the polarity right, in this case what goes into the BPS converter box.

Also, something that has been in the background here, unstated, is that with the low-capacity batteries (lithium-ion and not super-expensive) you can't use the humidifier heater. When you wake up in the middle of the night after your CPAP machine stops because of a power outage, you have to manually switch cables, disconnecting the AC power brick and plugging in the cable from the battery, and then you have to immediately tell the machine to switch off the heater ("Humidity Level" on the A10) and the heated hose if you use one. Otherwise the heater will quickly drain the battery and you'll be back where you started, only this time with a battery that needs to be recharged.

Also, as I mentioned in the review thread, that Gissaral pack defaults to 15V output and you have to manually switch it to 12V every time you use it, before you plug its power output cable into the Resmed converter box. That's a design flaw of that battery pack and a lot of others like it.

So you see one reason why the packaged "solutions" are so expensive: the product designers have solved some of those problems for you. But with the products from BPS, Medistrom, Resmed, etc., you still can't use the heaters.

An automatic switchover from line power to battery power is nice and convenient, but it can't be achieved for free with the Resmed machine. Either you use a UPS and put up with the inefficiency (and disable the audible alarm!), or else you spend a lot of money and effort to build a relatively complex system based on the larger, heavier batteries that will also let you run the heater.

[Fats Drywaller]

These two items are just for completeness and are, I'm afraid, not much help!  In other words, don't get your hopes up.  The general problem is either somewhat technical to solve, or expensive to solve, or both.

First, I happen, just by chance, to have the kind of setup that you want, except that the machine is not a Resmed.  My other machine is a De Vilbiss DV54, now obsolete (circa 2012), which has both AC and 12VDC power inputs and UPS circuitry built in: it automatically switches from AC to DC when AC fails, then it switches back to AC when that becomes available again.  Not only that, but it automatically switches off the heater when going to DC. And it works with that US$80 Gissaral pack without the US$70 Resmed-compatible converter cable.  You can still buy a DV5x these days (DV54 is APAP and DV53 is fixed-pressure), but it's not worth it unless you can pick up a used machine for very cheap. And it's not a good general replacement for the super-excellent A10.

Second, Medistrom sells one of those expensive "power solutions" including automatic failover (UPS), but a few people have reported, including in this recent thread, that the quality control at the factory seems not to be very good.  Maybe (this is only my guess) Medistrom has chosen lithium-ion cells from some manufacturer that turned out to be of inferior quality.  So not much help there either.

Sorry!

[Zainabpb]

I'm learning alot from you, thank you. It's all still very complicated and at this point I just hope the electricity never goes of. With technology at the forefront it is quite strange that any of these companies making these machines have never thought of building these batteries inside the unit itself. Surely it should be a standard feature. How many products you get these days( Cellphones and Laptops for one) that doesn't need to be plugged in to operate. I think you should design a CPAP with built-in standby battery pack FATS.

Thanks for the help. ?