Well, I wonder why they would have bothered to do that (especially since they seem to have gotten it so wrong)
I've shot my wad for now - I went into the saved game files and tweaked up all my engine room crew and compartment settings to boost efficiency, experience, etc. - it seemed to work when I loaded the game back up (the green bar was full and all the crew showed the increased stats), but no joy in terms of effect on battery life - none whatsoever
Oh well, guess maybe I'll try what someone suggested a while back - just turn "limited batteries" off but play like they're still on. Bummer.