Not wanting to overload you with more information but all the talk of batteries triggered some memories.
Back in the 'old days', when I was a lad getting up early in the freezing cold to deliver papers for £1 a day, I carried a tape player and of course, as they actually had to turn the cassette tapes they took a lot more power than modern MP3 players. I always used to be running out of battery power and often carried spares, but at times forgot. When that happened I had a few tricks to get that last bit of life out of the batteries. Swapping them around sometimes worked for a little while. Then when it got more desperate I could leave them for five minutes and miraculously I might then get another few minutes of juice out of them when I turned them back on, but they would do things like play at a slightly slower speed, which made the music sound funny. Then when I got really desperate I'd switch it to radio which required less power, but the signal wasn't great. When that died I had to walk on in silence. When on low batteries I also avoided any rewinding or fastforwarding of tapes as this really used up the juice. So i really had to adapt my behaviour to manage the energy and get the most out of it.
But if the next day I had forgotten to replace or recharge the batteries, I'd turn it on and I'd have a couple of minutes of magic juice that had appeared from somewhere, and I wouldnt remember that I needed new batteries till I'd walked a little bit down the road from my house then it would die on me, I'd remember, and annoyingly have to walk back home to get new batteries.
I don't know how this is relevant really, but it came to mind when I thought about my ME batteries being low. I guess with ME, maybe its like this all the time, that at best I am running on miniscule amounts of power each day and just trying to get something functional out of what I have left, having to pick carefully what I do and dont do. The batteries never get properly recharged. I'm just running on residual power.