I've been planning for prepping for several years, and am finally getting around to the CPAP.

I have a model that uses a transformer to convert 120V AC to 12V 5A for the actual appliance. I have an adapter that can connect to a 12V battery.

Does anyone have suggestions for a longer term, off-the-grid, battery and charging solution?

My general prepping philosophy is to minimize reliance on electricity because of the requirements for generators, outside fuel sources or expensive solar systems, but some things need electricity.

Thanks.

I've seen several examples of rugged, portable home designed units featuring deep discharge batteries topped off with solar photo voltaic cells... the quality and power output of the panels is rapidly improving, but I'm not in the business, so can only offer a suggestion...

for emergency backup, one of the 2000W inverter generators like the Honda EU2000 with a propane/natural gas adapter would be high on my list if I had to rely on a CPAP...

good luck

I would investigate a couple of things: an oral appliance rather than CPAP (for example: http://www.sleepsilently.com ), a nasopharyngeal airway, sleeping on your side, losing weight.

These things, if they can be made to work as an alternate to CPAP for you, in emergencies, beat the heck out of being dependent on an electrically powered medical device, which is inherently "not long term".

Assuming, for the moment, that you cannot use an alternative to a CPAP, I'd want to know more about your situation and possible alternative sources of power. Solar, hydroelectric, fossil-fuel generator and wind all come to mind but I don't know which could work for you in your circumstances.

I came across this chart for available usage times for CPAP machines for a 100Whr battery

http://www.eu-pap.co.uk/super-cpap-battery-pack.html

So I suspect you will be needing something like a Solar PV system around the 600-1000W and an 80-100 AmpHr 12V LiFePo4 Battery system.

$1200 for the Solar PV Panels and $800 for the LiFePo4 Battery and $500 for the LiFePo4 Charge controller and cabling etc. i.e around $2500, but this will depend on how much sunny weather you have.

Tirec,

I have a short answer, and a long answer.
Short answer

any generator would work for you as long as you have fuel for your timeframe.
For long term, a more energy efficient CPAP would be more logical.

looking at web reviews..
http://www.alaskasleep.com/blog/cpap-machines-camping-review-best-equipment

machines that come with a 2-3 day battery that are under 5 pounds.


Long answer

Using the machine you have
Taking worse case- The 12V 5 Amp can supply 12*5=60 watts per hour. If you sleep for 9 hours, that would be 540 watts per night.

To power this for longer than a few days, you either get a generator, or go solar.

For short/medium term,days to weeks, a small generator would be cheapest. ANY generator would give enough power for your current machine. Your only limit is fuel on hand.

Battery/solar.
So Battery wise, you want to store at least twice that, ~ 1000 watts minimum.

Using 6 or 12 volt lead acid is cheapest-
Energizer Golf Cart @ Sam's club (example only) 6 volt ~ 107 AH or around 856 watts.
I like golf cart batteries, as they are designed for hard use, and available anywhere.

To get to 12 volts buy 2, so 107 AH at 12 volts, or 1712 watts stored. Cost in Omaha 85.00 each, or 170.00 plus tax.

Panels- To fill those batteries in 1 day 1712 watts divide by # of useful sun hours in your area (average in US is 4.5 in a year) 1712/4.5 would mean 340 watts in panels.

If you are South, you need less panels. In summer you need less panel (more useful sun) Google of 200 watt panel ~ 200.00
So 2 would be 400.00.

Charger- Google Search for 25 Amp MPPT (Can handle up to 3000 watts in panels Seems to start in the 180.00 range.

SOOOOO>>>> to power your current one would cost as much or more, and mean 100 pounds of stuff. No joke, Lead acid batteries weigh a ton.
OR
A smaller CPAP of 2 pounds that only uses 20 watts in a night (google: battery powered CPAP) A transcend model has a 45 watt battery, and supposedly runs for 2-3 nights on it, plus can be hooked up with an adapter to recharge from 12 volt power supply.. car/ 12 volt/solar...

Does the machine actually draw 5amps at 12volts? Or is that just what the power supply is capable of providing? Look for a label on the machine to find out what it actually draws. Could be the power supply is sized to handle extra attachments, which you may or may not have installed. Example: A heated humidifier. If you turn off the humidifier/heater, you will save power.

I don't know this for sure, but it's a theory: In order for the CPAP machine to maintain pressure, it has to pump harder to overcome leaks. So make sure you have a leak-free fit. There are different types of masks available. I believe the full face mask will probably leak the most (thus having the highest power requirements), a nasal mask will be less leaky, and even less leaky will be nasal pillows. Now, just how much a leaky fit will affect power consumption, I don't know. As I said - it's just my theory. If you get up to go to the bathroom, turn the machine off. I have a friend who brings his CPAP on camping trips (we're lazy and stay in a trailer with electricity!) He gets up to pee, takes the mask off, and leaves the thing running. It sounds like a leaf blower over there by his bed, pumping its little heart out in a futile battle to maintain pressure.

"off the grid" is a bit open to interpretation. If you are thinking of it as a "lifestyle" or "permanent" or "semi-permanent" lack of grid based electricity, then solar seems the way to go.

OTOH, if you are thinking of some local problem that cuts the electricity, (think Katrina), but other energy sources are available, then I think generators are the way to go. If the CPAP is the only remaining item that needs electrical power, as others have pointed out, there are many small generators that will fit your need. If you have access to natural gas or propane, you should consider an automatic standby generator. It will more than cover the CPAP and provide power to some of the creature comforts, but most importantly the fridge, and safely storing food is a key thing. Between 10 to 15% of the folks (including me) in our neighborhood of 65 homes have installed them.

If you're in a Katrina-type situation and you have a generator, make sure it is securely chained down to something solid. No doubt, within minutes of you firing it up and the resulting noise, someone will try to steal it!

One needs to exercise caution in all situations. I live in a safe neighborhood. But I wouldn't let a thousand-dollar machine on wheels just hang out in my back yard without any security device. Security is not just "for Katrina-type situations." In other words, lock up your generator always.