Resmed Air Mini and Freedom Battery Compatability

[Kags1969]

I recently took my Air Mini on a camping trip and ran into a problem using my Freedom Batteries.  I have two Freedom batteries that I have used with my Resmed 9 as a camping setup.  I purchased the Air Mini, because I wanted something that was smaller and hopefully more efficient.   The Freedom batteries uses a 2->1 cable setup.  Plug the batteries into the split part of the cable -> then one into a 12 car adapter and use the 12volt power cable for the unit.   This worked great for the Resmed 9, however on the mini it would only work for about 4 hours and then it would start shutting down.  Batteries indicated 80%-90% charge, but no love for running the AirMini.    I see that ResMed has a 24Volt battery that works with the mini, but I would like to keep using the batteries I have if possible.  Has anyone else ran into this and developed a solution.  These are Freedom gen 1 batteries. 

Thanks,
Chris

[Crimson Nape]

Hi Kags1969! -
How old are the batteries? Mine finally wore out after 5 years. The battery tender always showed it was at peak charge. However, after a power outage, I learned that it wasn't holding a charge. A battery tester confirmed its weakness. Do you have a battery tester for large batteries that you can use to rule out this possibility?

-- Red