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Marine batteries are 7.5 Ah? If that's the case I can probably take a 12 Ah regardless of machine & pressure differences and take a little 1 watt solar panel just in case.

Edit: oops I forgot, our 1W panels are 6 volt. Ah well the 10watts aren't that big either.

Now that I know the unit has a DC power connection, I'm fully capable of using the equipment in our lab to test it's current draw and formulate the exact power/solar I need.

Hope you get the camping thingy all worked out and have a blast!

DH and I just bought a pop-up camper - we love camping but decided we are just too old and crabby to sleep on the ground any more (or get up from ground level). We plan to "rough-it" in more luxury these days and always use a powered site for the CPAP, lights and a fan.

Cheers,
xena

xenablue wrote:Hope you get the camping thingy all worked out and have a blast!

DH and I just bought a pop-up camper - we love camping but decided we are just too old and crabby to sleep on the ground any more (or get up from ground level). We plan to "rough-it" in more luxury these days and always use a powered site for the CPAP, lights and a fan.

Cheers,
xena

Lol, I don't blame anyone for that, but I'm gonna do it the good old fashioned way while I'm young enough to enjoy it.

Alshain wrote:? Marine batteries are 7.5 Ah? If that's the case I can probably take a 12 Ah regardless of machine & pressure differences and take a little 1 watt solar panel just in case.

Edit: oops I forgot, our 1W panels are 6 volt. Ah well the 10watts aren't that big either.

What do you mean "Marine batteries are 7.5 Ah"? While that would be small for a "marine" battery, "marine" vs. "non marine" doesn't really have anything to do with Amp Hours. What you want is a "deep cycle" battery. Some people mistake "marine" for "deep cycle", but the terms aren't equivalent. Some deep cycle batteries aren't "marine." Some "marine" batteries aren't deep cycle.

If you buy a "marine" battery, be sure it's a "deep cycle" marine battery, not a "starting" or "dual purpose" marine battery.

A 1 watt solar panel isn't worth bothering with. A 10 watt panel would probably be inadequate, too. You need something like 10-20 watts for 8 hours to run your machine (varies by machine, settings, leaks, and pressure). That is 80-160 watt hours. With a "perfect" setup on a sunny day, your 10 watt panel might get 80 watt hours. You won't get 100% efficiency charging and discharging your battery. You'd be lucky to get 50%.

For $70 or so, you can buy a 75-100 Ah deep cycle marine battery that looks and weighs like a large car battery. It will probably run your machine for several nights. Another $40 or so for a good trickle charger and battery box, and you can keep it in your house on charge all the time in case of power outages at home. It will be a spillable like a car battery, so if you turn it over while transporting it, you'll spill acid. Non-spillable deep cycle batteries are around twice the price for the same capacity.

The Respironics DC power cable is $25. If you want to hook it to the battery you'll also need an alligator clip to cigarette lighter socket adapter. Respironics wants $25, but that's a ripoff. You can probably find them cheaper elsewhere. You could also make a bare wire to cigarette lighter plug adapter.

By the way, don't try to run long DC cables. Power loss in cables is 100 times worse at 12V vs. 120V.

Oh don't worry, I'm well versed in the properties of DC/Solar power (I design these for a living). The only thing I don't know as of yet is how much amperage the unit draws at my settings. I'm going to bring it up to work when I have time and run some power simulations with our equipment to determine it's draw and then I will know exactly what I need to use. (I have access to various panels, so if I need more than 10, it's not a problem. I could get an 85 watt if I needed to, but I don't think it will fit in my little car, lol)

Remember that trickle charging a battery that under a load 24/7 takes a ~3x more to maintain then charging it while it is not under a load. Since the CPAP won't be in use while the battery is charging, you get a lot more efficiency from the charge. I just need to be sure that the battery is large enough have at least 2 days of autonomy and hope that I get enough sun to charge it for the remainder (if we get unlucky and it rains all week, we will find a hotel anyway). The batteries I will be using are non-spillable.

As for the Respironics Power cable, it's just a inverted mini-pin. I can get that for $1 or less from Mouser.