12V Battery Pack help for CPAP

Updating. Thought I'd put it here and add a new post at end. Looking for a new CPAP now, and thinking somebody here might know of a more efficient unit, and/or a great battery pack

I thought this went better here than in the Battery Forum as that specifies Flashlight Electronics, however if a Moderator wants to move it, feel free.

I'll sum up the long story below. I need a battery pack that will power a 3A, 12V draw for 8 hours, better would be 16 hours to allow an extra day between charges. It needs to be capable of 5-7 charge/discharge cycles a week as well as car travel on country roads for 20 minutes to and from charging. The ideal would be an easily portable 'pack' with a 12v female accessory (cigarette) socket.

I use a CPAP machine for help in breathing while I sleep. The machine works well and helps reduce snoring. However I live off grid, during the winter I don't like using up my hard won solar power. So I persuaded my insurance company to get me a battery pack when I started using it, I could get about a night and a half worth of power out of the pack. After about 8 months of fairly consistent use, it is down to about 4-5 hours of power. The medical supply provider replaced the pack without much problem. However I have a feeling the chemistry of the pack is the problem. It uses two "gel cells" giving a rated 14.4 AH @ 12V. My guess is the 5-7 times a week discharge/recharge cycle will kill this pack also. The bouncing back and forth between home and shop probably doesn't help much either. So I'm looking, in anticipation of failure, for a different pack. Any suggestions are welcome.

A different machine might be an option also. That one has a Lithium-Ion pack.

Is that 3A continuous load or does it cycle on/off, and how portable does it need to be? Will you be carrying it around or does it mainly just sit next to your machine? I was trying to help a friend with the same problem, coming up with a battery pack that could be taken camping and traveling.

For that kind of power, have you looked into a National Luna power pack? Not the portable jumpstarter packs, those don't have enough power. I'm talking about this

http://www.nationalluna.com/PPPack.htm

for running refrigerators while camping. It's basically a deep cycle marine battery in a box with some added accessory outlets. Not very cheap or lightweight, but you could easily build your own for about half the price. A mid size deep cycle battery would give you about 50AH, good for at least a couple days, and should last you years. No matter what, to supply that kind of power is either going to be expensive or heavy. Since you live off grid, do you have a generator that you can run for an hour or two each day to charge it?

Can you charge it off your car batt? When I first bought my home...100 years ago...I was so broke I used a marine deep cycle batt.

I put it on the floor of my car (120 amp size) running through a inverter (120 volt A/C 300 watt max) and a 75 ft extension cord to power a B&W 12' TV (you know...essential) fan and a couple lights.

Did this for a month or two and it worked well...no problems at all that I can remember...but I drove the car to/from work every day...so plenty of batt charging time.

I disconnected it from the car charging system when home so I did not risk discharging the car batt to low. Might work to augment your solar system.

For my CPAP I use an inexpensive 12 volt marine battery, deep cycle. These types of batteries are meant to be drawn down to almost nothing and be ready for a relatively fast recharge, and keep going and going.

I have been using Respironic CPAC machines exclusively for years. My current one is similar to this http://www.directhomemedical.com/machines-cpap-bipap/remstar-mseries-cpap-respironics.html This machine is easy to setup with a charger system of your own.

Bill

I'm trying to stay away from homebrew to keep insurance and medical provider happy. I can't believe that there are no manufactured Li-ion packs for 12v use that would meet guidelines.

See updated opening post.
In 6 years there have to be many more options :tired::thinking:

I am interested as well. Im a cpap user and would like to have an option. There has to be something out there...

http://www.thecpapshop.com/freedom-travel-cpap-battery-bundle

At $259, it looks OK. I'd rather have a 12V Accessory outlet {Cigarette Lighter}. This is better for single purpose use though.
OnAmazon, a bit more, would be nice to have Mah to compare

Hi!

Educate yourself concerning Headway LiFePo4 cells. I built a pack out of these to power my RC chargers at the field:

http://www.rcgroups.com/forums/showthread.php?t=1784667

You would need 4 cells in series for around 12V, and as many in parallel as you want for your application. A pack is easy to build as the cells have screw terminals.

Also you need a capable charger, an iCharger 206B for example, to charge your pack back up.