Backup Battery

[Patrickgpiper]

About a week into my CPAP therapy with my air sense 11. Hurricane season just began here in Florida and I’m looking for recommendations and/or options to continue CPAP therapy when the power goes out.

[mlmollenkamp]

There are a pretty wide range of solutions available depending on your exact needs.

The ResMed web site lists several solutions, and many online CPAP suppliers carry 3rd batteries that are specific to the S11. These tend to be fairly expensive ($350 or so). Most will run the machine for 8 to 10 hours provided you don't use the humidifier or hose heat. The humidifier especially uses a lot of power, the hose as well but less. Either use much more power than the machine. The biggest limitation to these is the run time, they are designed for about one night. This could be a limit if you don't have a source of power to recharge them.

Another way to look at the problem is to use an inverter to produce 120 V from a battery. I used to have a large marine battery in the basement with an inverter. It could run my WiFi, CPAP and a few other things for quite a while. Battery life was limited if I tried to do too much, but it would run a CPAP for much longer than the small batteries. It's not out of the question to run an inverter or power converter from a car using a long cable. A power converter is more efficient than an inverter, they are available for this application.

I've also built an inexpensive backup using a DC to DC power converter (a module from Amazon). The ResMed machines run on 24 Volts. But I have a lot of battery power tools that use batteries and always have half a dozen or so charged, 18 volt Ryobi. Each battery will run my S10 for 6 to 8 hours, the S11 would run quite a bit longer since its lower power. its not a complicated project if you are technically minded.

We don't get hurricanes nearly as often as Florida but when we do we are typically out of power for about a week. I've got a standby generator now so I don't worry too much. But I also have a Z1 travel machine and a 3rd party battery pack (12V) that will run it. This is both a backup and a setup for travel.

I hope this helps.

[Dog Slobber]

I'm thrilled with my EcoFlow Delta2.

It's expensive, but has features that few other (maybe none) backup solutions have that are ideal for CPAP use.

Here's a topic about the Delta, within are some posts I made about many of the features:

viewtopic/t189452/If-you-can-afford-one ... s-hit.html

[kellygary76]

Any sort of battery backup will work. the issue is how long will it provide power.

I found this thing that uses my batteries from lawn tools.

https://duckduckgo.com/?q=ryobi+power+b ... 0BG_02.jpg

[Dog Slobber]

Any sort of battery backup will work. the issue is how long will it provide power.

I found this thing that uses my batteries from lawn tools.

https://duckduckgo.com/?q=ryobi+power+b ... 0BG_02.jpg

I don't think this is very good advice.

• No, any sort of battery will not work.
• How long it will provide power is a critical part of the decision. In all but the highest capacity power-tool batteries, capacity will be a problem.
• This is an AC-inversion solution, a lot of capacity is lost when inverting DC to AC. AC-inversion solutions, while not ideal, are fine when their is a lot of capacity, which this doesn't have.
  Power-tool batteries are expensive

If you happen to have some larger capacity power-tool batteries and an inverter, then it will do in an emergency. But don't spend any money towards this as a CPAP backup battery solution

[mlmollenkamp]

I think it would work. I would never purchase power tool batteries just for CPAP backup, but I have half a dozen Ryobi batteries that I use with my power tools. The ResMed Power Station (RPS) II is 97 Watt hours and will run the S10 for up to 13 hours according to ResMed. The S11 is quite a bit more efficient than the S11 so it would last longer. If the Ryobi power inverter is 80% efficient and the ResMed power supply is also 80% efficient (both are likely better than that) you need 150 watt hours to equal the RPS. A 4 Amp Hour 40V battery is about 160 watt hours so it should more than equal the RPS. This isn't a bad plan if you already have power tool batteries and other uses for the 120V inverter.

The more practical solution is a DC converter. The ResMed Air 11 converter will take 12 to 24 Volts and power the machine with or without the humidifier. There are 3rd party converters like it as well which is what I have for my S10. These have a plug for a car lighter socket. A Ryobi 18V 6 AH battery through this converter will run my S10 without the humidifier for about 7 or 8 hours. There is a simple adapter called a "Power Wheels adapter" that will connect to the battery can be wired to a car lighter socket connector. You can't travel with this kind of thing, but for a home backup its pretty practical, especially if you already have power tool batteries. There are adapters for most brands of power tool batteries, but the limitation is the ResMed converter isn't designed for more than 24 Volts so the 40 V batteries won't work. The ResMed converter, or its 3rd party clones will also work in a car or airplane. Its a very practical solution for an RV for example. 3rd party converters for S10 or S11 are available for less than $50. 3rd party Ryobi 18V batteries are also pretty inexpensive. There are also battery chargers that will charge power tool batteries from a car lighter socket which makes the setup practical for longer power outages as long as you have a functional car or truck.