Portable oxygen generators

A while back, I had asked about the use of a CPAP unit with RV travel and got some good answers from the forum members. Since then, I have figured out that we could use a converter that goes from 12v dc to 24v dc so the CPAP can be run directly from our on board batteries.(it uses a converter to go from 120 to 24v DC)  I am also planning on adding four 100 watt panels and a Bogart charge controller to really help keep our batteries charged.

I'm back with another question...My wife has to use an oxygen concentrator at night and we are looking at both an "in home" design and a portable unit. The biggest problem is power. She needs a unit that supplies continuous flow NOT pulse. I really feel that a portable unit would be workable as they can run from 12v DC.  The others require AC but I believe several can use AC/DC. Anyway, we would have to use an inverter with these (as we want to be able to boondock/not run the genset all night) and it appears that the watts required to run the machine would drain our batteries pretty quick. The Everflo she has at home is rated at an avg consumption of 350 watts on 120 v AC.  Some of the portable units avg use can be 100-150 watts at 2 liter/min flow.

I know I wrote a lot but I wanted to give a better idea of what we want to do. I am hoping that some of the forum members have experience in this situation already and can give us some ideas/real world imput that would help us in our search for a solution. I am leaning towards the portable units such as the Resprionics SimplyGo (portable) or their SimplyFlo (home unit but AC or DC power). The possible "fly in the ointment" is the max flow limit of 2 liters/min. If her needs increase then we have a problem.

Any ideas/suggestions from any of you? Thanks ahead of time for any responses.... Gary and Jena Dent

One other parameter I left out is that we are in Colorado at about 7500' altitude and some of the areas we want to visit and boondock can exceed that easily. So the higher the altitude limits, the better.

You can also get 12 volt CPAP machines.

The only concern I have with any Medical Device is making sure you have ENOUGH battery. What are the power requirements.

FOR a DC system WATTHOURS - Watts (Average) Times run time for both the CPAP and the Oxygen concentrator run is continous so Watts= Watts(Average)

Now we are to WATT hours = Watts times hours

AMPS = Watts/12 so AMP HOURS = Watthours/12  Figure 8-10 hours run time per night and 24 for the O2 Machine.

Let us assume 100 watts.  that's 1000 watt hours for a 10 hour stretch without Generator.
or 1000/12 (If powered direct from battery) or 1000/10 (using any kind of convrter or inverter the rounding of voltage accounts for conversion losses).

1000/12 85 amp hours..  if I did the math right.

Battery capacity.. For MARINE/deep cycle try to use no more than 1/4 (25% of the battery capacity)

GRoup 24. about 75AH each
Group 27 and 29,, Just under/over 100 (like 95 and 105)
Group 31 130
GC 2 (Six volt golf car bateries which are TRUE DEEP CYCLE and can go down to half full without suffering major damage) 220 give or take 10 amp hours.. Size 4D same capacity but may or may not be DEEP CYCLE.

YOu need one pair of GC-2 to be safe. if drawing 100 watts all night long.  Other wattage requirements you can adjust up or down.

John...thanks for the reply. I'm running 4 GC-2 batteries I got from Sam's so I've got about 430 amps (215 @ 20 hr rate times 2). I need to look again at some of the units we are considering. It gets confusing when I'm trying to estimate whether or not our setup will suffice. I want to add four 100 watt panels and charge controller to help keep batteries charged. I don't want to make an expensive mistake, that's why I'm asking for input from members like you. Thanks...Gary