simlpe inverter setup question

[akghound]

Here is the deal. My sister in law is staying with us for a few days and needs an oxygen machine running almost all the time. We shut all power to the house off at night and during most of the day. So here is what I have to work with; I have a 1000 watt, 12 volt inverter, a B&D 25 amp smart charger battery charger. We run the generator about 4 hours each evening and a couple hours each morning. I need to get batteries.
The oxygen machine is 115vac, 4.2 amps, 520 watts and needs to run almost 24/7. I would like to set up RV / Marine batteries to handle the setup. How is the best yet not over expensive way to do this? Keep in mind that this setup will only be needed a month or so, it is temporary.
thanks … Ken Gardner

[Tom Reed]

Well that puppy is using around 13 kw per day. That's as much as my whole house well pump and all! I calc you'll need around a 800 ah battery bank to handle the load. About 7 of the 120 ah marine/deep cycle should do it.

[akghound]

More info. I guess it would help if I posted run time for oxygen machine. It well need to be powered from the inverter for 6-8 hrs at night and 8-10 hrs during the day. Will 4-6 hrs charge time with the B&D charger be enough?

[akghound]

Yikes Tom. You are scaring me! I have a little Geo 3 cyl car I can run prettty cheap to charge the batteries. Maybe run it during the day and provide a battery bank for only the 8 or so hrs of night time use.

[Tom Reed]

Your battery charger is not enough to even carry the load. Might be more economical to buy her a tank of medical O2. The calcs were based on a 15 hour run time. It's good to make conservative estimates on life sustaining devices. 

[akghound]

Your battery charger is not enough to even carry the load. Might be more economical to buy her a tank of medical O2. The calcs were based on a 15 hour run time. It's good to make conservative estimates on life sustaining devices. 

Starting to look that way. Thanks Ken

[quinnf]

Welding O2 is purer and much cheaper.  Then, when she leaves, you have half of an oxy/acetylene welding setup, so you might want to go to Harbor Fright and get the torch for it and have fun melting metal without the guilt/recriminations from the wife about buying another man-toy.

There's a system to these things.

Quinn

[Ronmar]

What type inverter?  Will this medical machine accept the power available from this inverter?

[akghound]

Quinn. I like the way you think.you have the best plan yet.

What type inverter?  Will this medical machine accept the power available from this inverter?

It is an Elcheepo WM $70 Special. It handled the power ok, all that seemed to work ok. I was just trying to figure a way to not run the big genny so much.

[bentcrafter]

In most locals, you can rent o2 bottles. Run the oxygen concentrator during the day - bottle at night. I personally would feel much comfortable with her on the more reliable bottle, than having a potential genny/inverter disruption in the middle of the night. And having a bottle of o2 around will provide critical backup during the day. 

[bentcrafter]

Then, when she leaves, you have half of an oxy/acetylene welding setup,..

Personally, I'd keep the OC. But considering the OP's circumstances, I would strongly discourage taking her's.

[mike90045]

A few days.   3 days ??  8 days 

More than 2 or 3 tanks, you should look into a cryogenic dewar of LOX @ 200 psi.  use the boil off vapor, should last you a couple weeks.

I don't understand how a tank of welding ox is "purer" than medical ox.


Medical devices (o2 concentrator) will likely NEED a pure sine wave, the concentrator will have a motor in it that may overheat on mod sine.

[akghound]

You guys are so good! We are here laughing our heads off. We went the bottle route.

[Tom Reed]

Inquiring minds want to know. Did you go with the medical or welding O2?