OK, reporting. My battle DR1000 battery finally started its slow agony: setting a DR1000 to do no power saving, it will normally go from 100% to 'low battery' condition in about 12 hours; mine did in about 4 now, so it was time for a change.
Now, dremeling out the inner ribbing of the DR1000 is dangerous and changing the battery isn't guaranteed to work...
As some of you may know, I now use a custom made cover
of which I never take out the DR1000. This gave me the idea of sticking 'large' batteries to the back of the DR with duct tape (the 5mm thick lump is barely noticeable with the cover on) and passing the cable through a single hole in the back cover. This allows for more flexible testing with different batteries without risking too much the unit integrity.
So, I set my DR1000 to not shutting down automatically and connected it to the 5240110 2200mAh battery to see how long it took to discharge. It kept responding to touch for longer than 18 hours before it froze (I set up everything before going to sleep and it was still alive the morning after). However, it gave a constant battery reading of 100%. After that it has gone through four or five cycles of very fast charge and discharge (as reported by the gauge), slowly extending the cycle period, but still not up to par with the original battery.
Since the first time this battery gave energy for a good 50+% longer than an original one in good condition I conclude the whole change stuff works but we still need to learn how the DR battery gauge adapts to a new battery. Our friend Mackx apparently wrote code for that, so we'll be testing that in this other thread