How many batteries would it take to run a Cpap machine for 8 hour ?

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Jay Waller

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Posted 2 months ago

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summetj

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How much power (in watts) does your CPAP machine use? Look for a sticker on the back/bottom that gives you a watt draw, or a amp usage at 120 volts.... Or even better, use a kill-a-watt meter overnight to measure the actual watt hour draw over the full 8 hour period.

Many CPAP machines, depending on pressure settings, are between 30-60 Watts.

Assuming you have a 7.5 AH battery at 56 volts * 0.85% efficiency that would be 357 watts of power, able to drive a 60 watt load for 5.9 hours (or a 30 watt load for 11.9 hours).

So, to answer your question, a single 7.5 AH battery might be able to run a CPAP machine for a full 8 hours depending upon the watt usage of your machine. Unless your watt usage is at the very low end, none of the smaller batteries (2.5 4.0 or 5.0 AH) would be able to drive it for the full 8 hours, and you would probably need a combined AH rating of 7.5 or slightly more to drive it for 8 hours.

Typically the loss of a CPAP machine while sleeping isn't immediately life threatening, but depending upon your situation you may wish to consider a medical grade UPS as opposed to a consumer grade camping accessory....
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Timothy

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I have a Resmed S9 CPAP, that I use at a pressure setting of 10.   I also have a Medistrom Pilot-24 battery that I can use with it that is rated by their documentation as 98Wh @ 24v DC (or 19000 mAh @ 5v USB).    The pilot-24 can power my CPAP, without the humidifier, for 2.5 nights of camping, or around 20 hours of actual sleeping time.

I'm considering getting the Nexus Escape to recharge the Pilot-24, rather than using it to run the CPAP itself, since I go on longer than 2-night camping trips a couple of times per year, and have a longer than two night power outage at the house every couple of years, it would be a nice backup power supply for my backup powersupply. :)
(Edited)
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summetj

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It sounds like your Pilot 24 has a 95-98 Wh battery.  A 2.5AH Ego battery has 140 Wh, a 5.0 AH ego battery has 280 Wh, and a 7.5 AH Ego battery has 420 Wh of capacity. [brand new]

So even with efficiency losses and age of batteries, I would estimate that the 2.5 AH battery could fully recharge your Pilot-24 one time, and the 5.0 AH battery could recharge it twice, and the 7.5 AH battery could recharge it 3-4 times.
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Timothy

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Exactly so! 

98 Wh is what the specs say.  That's to comply with TSA regulations that limit the maximum capacity of carry on batteries to 100Wh.

I'm not worried about flying with my battery.  For me, it would be more for driving to boy scout camping events with my son's troop.  I would just put the 7.5ah battery in the car, and charge up my cpap battery every couple of days.