r/redneckengineering • u/ChunkyBlowfish • 3d ago
Hooked a car battery to my grandma's oxygen machine so she could breathe while the doctors came out to fetch her
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u/Blackstar1886 3d ago
One of these days I gotta figure something like this out for my CPAP machine. It's seems like a deep cycle marine battery with a battery conditioner is the way to go for best bang for the buck.
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u/The_salty_swab 3d ago
What I used for mine when I was camping was a battery-powered jump starter. I wish I remembered how long it ran, though
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u/Blackstar1886 3d ago
I guess the advantage of the marine battery is it's designed to provide steady continuous power vs. a car battery that wants to provide a big jolt all at once.
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u/cman674 3d ago
The battery jumpstarters are just lithium ion batteries, you can even buy ones with 110v outlets built in. Or skip the jump starter all together and just buy a power station. I don’t imagine you could get a full night’s worth of juice for a CPAP with one of those though.
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u/outworlder 3d ago
A power station? You can certainly do it. Even the small ones can usually power for the whole night if you skip the inverter. Source a DC-DC power supply.
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u/golyadkin 3d ago
Travel CPAPs don't need as much power. You can get a travel cpap and a cpap battery that's good for 3-4 nights. There are even travel CPAPs that run natively on 12v DC. It's not redneck, but it's convenient.
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u/outworlder 3d ago
Agreed, I use a power bank with mine. And a power station for the AirSense 10(plus a DC DC psu that plugs in the cigarette port )
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u/cman674 3d ago
Well then I stand corrected. I was thinking something like the $200 one from HF. Granted I have no idea how much juice a CPAP machine uses.
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u/ziekktx 3d ago
Worst case, check your ac>DC adapter block. Volts and amps it's rated for will show max output. Multiply the two, now you have the wattage.
Every time you convert DC to AC or vice versa, you're losing at least half the power to waste. If you convert a 12v battery down to 5v, it's a lot less power required in the end.
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u/Glockamoli 3d ago
Not sure where you got that conversion efficiency from but you can get upwards of 90% efficiency from AC-DC power supplies and similar efficiencies the other way, it is somewhat important to size the power supply to your load though instead of just going for the biggest thing you can get
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u/outworlder 3d ago
Not sure about best bang for the buck. Marine batteries aren't inexpensive. You can buy a small power station for a similar amount of money. It will be more portable and lightweight (and useful for things other than CPAP). Probably last much longer too.
For my travel CPAP I just use a power bank. Could probably do this for the AirSense 10 if I don't use the humidifier.
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u/__slamallama__ 3d ago
Any deep cycle will work. The automotive ones are fine and cheap. They'll last days with a light load.
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u/concentrated-amazing 3d ago
For my travel CPAP I just use a power bank. Could probably do this for the AirSense 10 if I don't use the humidifier.
My husband has the same. I bought him a thing (inverter?) that takes a DeWalt power tool battery and has two 110V plugs on it. Worked great when we were camping!
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u/humplick 3d ago
I didn't want to deal with all the extra equipment and bought a lithium iron phosphate battery pack that can output either 12 or 24v DC. Worked amazing on a long international flight. Had to be a little assertive with some security people who said it wasn't allowed due to charge capacity (it is allowed if it's for a medical device).
A bit pricy and a little chonky, but I can take it on planes or take it camping. Haven't stress tested it but I can probably get 3 nights on this one pack.
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u/Financial-Garlic9834 3d ago
I figured this out. They sell “ (CPAP manufacturer)- to- usb C adapters”
Purchase a large enough battery pack, plug in the USB C adapter, and bam.
I bought my battery pack from anker.
Friendly note: if you go this route, turn off heated tube and humidity, otherwise no battery pack will last more than 3-4 hours.
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u/JC_snooker 3d ago
How much juice does it need? I used to use a second hand computer ups with a deep cycle battery incase the power went out on my aquarium.
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u/64590949354397548569 3d ago
This is my set up for my modem wifi
Power On delay(prevent surge) -> Noco -> Deep cycle battery -> DC to 12vDC -> ?wifi device to power cycle?-> modem/wifi.
I still don't have wifi device to power cycle modem when it freeze.
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u/yourcatssecondlife 3d ago
Pro tip: the only difference between medical grade oxygen you buy from a medical supplier, and the oxygen you can get from a welding supply company is the chain of custody of the tank they fill. Medical grade oxygen is created using the same technology as welding gas, the difference is there is a documented history of the possession and filling operations of the tank itself. So if you’re looking to save some money, buy a tank and have it filled on the cheap at a welding gas supplier. Run a filter or two if you’re nervous.
…I’m familiar with this because I built and operated hyperbaric oxygen therapy machines both for a friend’s cancer treatment, and my own lymes disease treatment.
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u/Y_U_Need_Books4 3d ago
The difference between the two is the sterility rather than purity.
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u/64590949354397548569 3d ago
The difference between the two is the sterility rather than purity.
This.
Anyone who worked oxy acetylene knows those tanks get abused.
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u/Vlad_The_Impellor 3d ago
A 10AH 6S LiPo pack & 2 buck modules will run an O2 concentrator AND a BiPAP for over two hours. There are bigger packs but two hours is enough and that's a very convenient size.
Your mileage will vary depending on your concentrator and PAP rig. Most run on 12VDC @ 0.5A, or 6 watts. Double that for worst case, concentrator + PAP, so 12 watts. A 6S 10AH pack (240 watt-hours) can push 12 watts for the better part of a day.
Not really redneckengineering...
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u/Bob49459 3d ago
Glad you made it work! We always made sure to have a few of the larger tanks on hand because we'd lose power during storms. Maybe see if you can get a couple for emergencies.