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Lithium Ion battery for CPAP machine? Answered

I'm trying to figure out how to power a CPAP machine (this one) for a few nights of backpacking/camping. Does anyone know how to hook it up to a lithium ion battery (and what type to get) with out forking over all my money to the medical supply industry? I'm dying to go backpacking for at least a night or two.

any help would be appreciated.

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If you are thinking of making your own Li-ion battery pack, I would ask you to think long and hard about whether it makes sense to connect on of these to your CPAP device. It is, after all, a life-support system that you use while you are unconscious.

Please now google "lithium ion battery fire videos" so you can see just how dangerous these things can be. Holy Cow, this is scary stuff!

Unless you can find a commercially-made 12 volt lithium-ion battery pack that contains an internal battery management system (BMS), and can also find a matched charger specifically for 12 volt lithium-ion battery packs, I wouldn't try this. A BMS prevents you from either letting these packs discharge too low or from charging them too high, and keeps the individual batteries in a pack "balanced." Discharging them too far makes them risky to recharge. Charging them too high risks having them heat up, go into "thermal runaway," and catch fire.

Assuming you find a commercial product that meets your needs, I would still test and verify that the battery pack can supply enough energy to run the CPAP for as many hours as you will need to run it all night (and if camping, for all the nights you will not be able to recharge.)

Thinking that the EBIke industry was gouging people on batteries, I thought I would save money by building my own Ebike battery packs. I read widely, designed and built an EBike battery spot welder that works well, and took apart several "dead" battery packs to see how they are made. After all this effort, I concluded that that the commercial packs, expensive though they may be, are worth every penny because of all the safety features they contain to prevent undercharging, overcharging, short circuits, overheating and fire. Also, they are fairly difficult and laborious, (though not impossible,) for hobbyists to make safely, because one accidental short circuit could cause a fire that you probably wouldn't be able to put out until all the fuel in the pack was consumed.

One final word of warning. I've read that Li-ion batteries give off hydrofluoric acid when they burn. If your homemade battery pack were to ignite in your tent while you were asleep, it could damage your lungs catastrophically and possibly even take your life. After much effort, I've concluded, therefore, that well-designed commercially-made battery packs are not really so expensive after all.

Disclaimer: I have no relationship whatsoever with the commercial battery industry.

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mpilchfamily
mpilchfamily

8 years ago

Look at the power brick for the unit. The unit uses 12VDC. Find a 12V battery that offers the most Ah that fits your budget and is a suitable size for going backpacking with. Get a DC jack and some wire and your all set. Just make sure you get the positive and negative leads in the right place.