Bump...
Ended up getting a non-Neato battery which works great in the D3 both running and recharging on the D3 base. The fully charged battery will power the D7 just fine, but will not charge on that base (and I know they aren't interchangable from prior contact with them years ago), but I did try the D7 on the D3 ... just because.
The battery was supposed to work for all D3-D7s btw.
Sooo... my D3 is now happy.
Think I'll crap-shoot another one (different source) and see what happens?
I couldn't get into MIT ..... Midvale Institute of Technology
... but this one has me ???