WARNING to CPAP Users: PREPARE for the Unexpected - When the power goes out

[archangle]

Unless your town experiences power outages every so often it is not worth wasting time and money in case of the remote chance its out for several days.

Thats like building a fallout shelter in case Russia attacks.

The odds of a multi day power outage are a lot larger than the odds of nuclear war. (I hope). Also, the fallout shelter is much less of a complete solution, and costs a lot more than a good CPAP power backup. The CPAP power backup is also very nice to have even if it's only a few hours worth of power outage.

[Konnarock Kid]

That's a solution for another problem, but what about power failures for a few days or more? How many hours wil it run your CPAP?

[archangle]

That's a solution for another problem, but what about power failures for a few days or more? How many hours wil it run your CPAP?

That depends on CPAP machine, settings, leaks, battery size, battery condition, direct DC connection vs. inverter, inverter efficiency, heated humidifier/hose use, etc.

There's a ResMed doc on battery usage in my signature line.

My my PRS1 CPAP, no heated humidifier or heated hose, I draw about 10 watts on the AC power line running at 16 cmH2O. Powered directly off of DC, that's less than 1 amp at 12 V. With a 100 amp hour battery, that's theoretically 100 hours. That's 12 nights of 8 hours. If I use the heated humidifier, I draw around 30 watts average, but that probably varies with the settings, and room temperature and humidity. That would be 4 nights in theory.

Your mileage may vary a lot.

If you want to use something like a generator be careful. If you don't maintain it and test it, you may find it doesn't start when you need it. You have to have fuel, and it may not be readily available in a disaster. Modern gasoline doesn't store well. The neighbors may not like you running a generator all night long.

Solar panels can work, but the panels have to be big enough to keep your batteries charged. Your battery system has to be large enough to last through several cloudy days. You have to maintain the system and the batteries or they might not work when you need them.

[GladiatorConjugate]

I have a question. would a UPS for a computer work with cpaps?

[surferdude2]

Yes, but not for a very long cycle. It's all about ampere hour capacity. Typically you'd get minutes not hours. There is also the consideration of the stepped approximation of a sine wave voltage output that the typical UPS produces and how it may affect your equipment.

[Sleepster]

That's a solution for another problem, but what about power failures for a few days or more? How many hours wil it run your CPAP?

Every couple of decades or so a hurricane will do that to us around here. My plan for those events is to have an extra car battery on hand. As long as I have gasoline in my car I can install the battery in the car, drive around and charge it up. Alternatively I can use a generator or solar panels to charge the battery.

It's all about being prepared. The alternative is to suffer through several days of untreated sleep apnea. Not a lot fun, especially with the stresses of being without the grid, grocery stores, and other amenities we've come to expect as part of a normal existence. There are few things as enjoyable as having the grid come back up.

[player]

My computer UPS units all beep when they are working when the power goes out.

Is that the same with all UPS' units?

What about the Medistrom Pilot-12/24 units? Their website gives no indication of run time...

[GWild]

My two cents ...

I have an 18AH battery with the connector attached that plugs into my 12 Reperonics RemStar 550P (my older machine). Yes, I need to update the plug for my newer 560P. The battery fits into the one side of the ResMed bag,

I did the battery because I wanted to be able to camp under the stars - and enjoy it. The battery allows 2 to 3 nights (night 3 is iffy). NOTE: I do NOT use the humidifier on battery.

I have a small inverter for car use to run the small charger on day 3 (before night three). D1,N1...D2/N2...D3charge/N3...

At home, I have that battery setup ... I also have my computer UPS that has another set up batteries that will power up the CPAP for a night or two - depending on how long it ran before the computer actually got shut down.

Longer term (while the fuel supplies last) the car recharge method would get me by, and I have a couple 15W solar panels to recharge with. But if things came down to that - not sure surviving is worth it since living in a zombie land doesn't sound like that much fun -- you can only carry so much ammo, and the zombies will likely shoot back.

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My computer UPS units all beep when they are working when the power goes out.

Is that the same with all UPS' units?

What about the Medistrom Pilot-12/24 units? Their website gives no indication of run time...

Mine has a button to shut the beep off.

[SuperSleeper]

Just a cautionary note for those who have lead-acid batteries (the more common ones)... Don't think that you will be able to hook up an 100 amp-hour (marine type) deep cycle lead-acid battery for 100 hours of use with a 1 amp draw or that a standard 18 amp-hour lead acid can be used for 18 hours with no problem... you'll be sadly mistaken if you let the battery get discharged that low. With lead-acid batteries, to be safe, you never want to discharge them too low (less than 70% of their overall amp-hour rating). Might work for you for a couple nights, but try recharging them and you'll find you have damaged the battery and now it's capacity has been ruined (although you may be able to get a few minutes of use out of it).

And keep in mind that "open-terminal" battery testers do not measure capacity. You need a load-tester for that. So when you ruin your lead-acid battery by discharging it too low, you can recharge it, and it may even show something like 13.0 volts open terminal, but if it's dead, it has no real capacity (ability to run something for a period of time). And you'll have a false sense of how well that battery will perform for your CPAP machine when you really need it.

As far as the common lead-acid batteries (either sealed or the type where you can add distilled water), you CANNOT discharge them much below a 70% charge numerous times without completely damaging the battery. Again, we're talking about the kind of batteries that are like car, boat and UPS batteries (commonly lead-acid).

So the effective time period for use for most of the large car-battery-sized 100 amp-hour lead-acid (marine hybrid) batteries is really only about 2-4 nights for most folks on CPAP... (perhaps 32 hours of run time depending upon the CPAP machine's amperage draw).

Some more expensive batteries (lithium-ion & others) will allow you to deep-discharge with no damage to the batteries' capacity. But not the more common lead-acids - if you discharge those that deeply, they're toast as far as future capacity.

Just a clarification so folks aren't confused on these battery types.

[GWild]

I agree with the non-engineer level understanding of batteries. Use - aka - depth of discharge and life expectancy are often ignored.

My 18AH battery will power a third day but results in what I consider excessive DOD. Also, my battery is rated to 200 100% DOD cycles; but would last a lot longer at 30% DOD, or over 1000 cycles. In my use, I'm somewhere around a 50% to 60% DOD.

For my use, even 200 cycles means several years... and 500 cycles is a lifetime.

Anyway - a good source of sealed lead-acid batteries and info is Powersonic, and their general data sheet.