USING A CPAP ON AN AIRPLANE

[pavelow360]

I was recently diagnosed with severe sleep apnea and I fly long hours on a jet for a living. I have to sleep on the airplane. I have been told that if you plug something with a motor such as a vacuum cleaner into the airplane's outlets, it will burn the motor up. I assume that I will not be able to use the machine on the airplane unless I get a battery. The outlet I would use is 115 volt / 400 hertz. Does anyone have any experience with this sort of issue?

[CapnLoki]

I was recently diagnosed with severe sleep apnea and I fly long hours on a jet for a living. I have to sleep on the airplane. I have been told that if you plug something with a motor such as a vacuum cleaner into the airplane's outlets, it will burn the motor up. I assume that I will not be able to use the machine on the airplane unless I get a battery. The outlet I would use is 115 volt / 400 hertz. Does anyone have any experience with this sort of issue?

I'm surprised no one has responded so I'll get the ball rolling. First a disclaimer: I have no direct knowledge here, I've never used a cpap on a plane, and I didn't find any personal info, so there's still a lot of work to be done here.

But here's a few things I've found:. The official line from the airlines is usually that 400hz is only for maintenance crews and will likely blow up anything plugged in. On the other hand, there are lots of flight attendant comments about using their iPhone chargers with no problems. Interestingly, ResMed actually says to ignore the "50-60 Hz" rating and go ahead and plug into 400 Hz:
http://www.resmed.com/us/en/consumer/su ... pment.html about 2/3 of the way down.

Respironics has no such comments, but I wouldn't be surprised either way. However, they suggest using Empower which is the 15V DC 75 watt outlet some airlines provide. There are adaptors for this that would work fine with Respironics and other 12v systems.

By the way, the reason for 400Hz is that historically it saved a lot of weight because the alternators can be smaller. Nowadays it probably isn't really needed, but the tradition is hard to break.

[BlackSpinner]

Are you sitting in a standard seat? If yes then you can't always count on a working plug. Plus a lot of the planes I have flown in recently don't have have them anymore, they have USB ports.

[JDS74]

While it is possible to convert from 400 Hz to 60 Hz, the cost of such a device is very high.
So, you are likely to need to carry a battery that may weigh up to 30 pounds of so to power a cpap and its humidifier.
I suspect that aircraft humidity levels are quite low so that extra humidity will be required.
Do you have a means of recharging a rather large capacity battery between flights?

My machine draws 80 watts at 12 volts or about 1 KW per hour of operation including a heated humidifier.
Edit: Mea Culpa, my arithmetic is in error. 80 watts at 12 volts is about 7 amps times 8 hours yields about .56 KWH not the 1 kwh I calculated.
Most larger auto batteries are rated at something like 60 amp hours and a 80 watt draw works out to be about 7 amps continuous. A 60 amp hour battery would be almost completely drained after an 8 hour period so you would need a couple of them in parallel to meet the requirement without killing the battery each trip. For this use, a deep cycle marine battery would be a good choice.

If you can get away without the added load of a heated humidifier, then the power requirements would be quite a bit less.

[CapnLoki]

Sorry, there's a bit too much misinformation to let it go without comment ..

While it is possible to convert from 400 Hz to 60 Hz, the cost of such a device is very high.

This it true, but what we really need to do is convert 400 Hz to 12 or 24 V DC, which is what most cpaps run on. ResMed claims its power brick works OK, it would be nice to verify this and to find out about Respironics.

So, you are likely to need to carry a battery that may weigh up to 30 pounds of so to power a cpap and its humidifier.

There are alternatives - I can't imagine even considering a 30 lb battery as a routine.

I suspect that aircraft humidity levels are quite low so that extra humidity will be required.

Yes, this is an issue. Aircraft humidity is around 12%, definitely lower than most would prefer. (The new 787, being largely composite and thus suffers less condensation, maintains much higher humidity.) However, using a humidifier while flying is problematical enough that most folks would probably learn to tough it out. More below ...

Do you have a means of recharging a rather large capacity battery between flights?

Small chargers aren't really that big. The larger issue here might be if the travel is every day, because it takes 6 to 12 hours to really top off a battery. Many off the grid users habitually only charge to 85%, which takes a toll on batteries. But if the travel is every other day, it should be possible to recharge.

My machine draws 80 watts at 12 volts or about 1 KW per hour of operation including a heated humidifier.

This is my big issue - the "80 watts" on the converter does not indicate the actual load, its the maximum load the power block can provide. In practice the load, even with a humidifier, is much less. (The "1 KW per hour" is so far off it must be a typo - even 80 watts would be 0.64 KH Hours for 8 hours)

Here's my study on the load of various settings:
viewtopic.php?t=102179
Normally I work in Amp-Hours, but I'll use Watt-hours here since the airlines prefer that. In summary, the pump is about 50 Watt-hours. A very minimal use of humidity would add another 50 Watt-hours, and that would triple or more if you tried to get what most would consider "normal" humidity.

Most larger auto batteries are rated at something like 60 amp hours and a 80 watt draw works out to be about 7 amps continuous. A 60 amp hour battery would be almost completely drained after an 8 hour period so you would need a couple of them in parallel to meet the requirement without killing the battery each trip. For this use, a deep cycle marine battery would be a good choice.

A 60 Amp-hour battery would easily cover a night, but it would weigh 50 pounds or more. Staying with lead-acid chemisty, a UI AGM would give 35 AH at 24 lbs, but that still rather more than I would consider. More interesting for this discussion might be a 7AH AGM battery that weighs about 5 pounds and is 84 Watt-hours. These are cheap ($18) and are commonly available as UPS replacement batteries. This would work if humidity is not needed.

But really this discussion should be about Lithium batteries. Airlines (and governments) limit the amount of Lithium (which is flammable) to about 100 Watt-hours, although you might find a slightly larger battery, up to about 140 Watt hours. This means that a Lithium pack would cover most pump needs for one night, but adding humidity would be difficult. I've never used one, but some have reported success with such Lithium battery packs. Those marketed for charging cell phones are under $150, but versions built for cpaps will run about double that.

If you can get away without the added load of a heated humidifier, then the power requirements would be quite a bit less.

Very true - its really the only practical way to do it.