I think the answer is probably yes, but it would be really hard to do and very expensive. It would be virtually impossible to find a manufacturer who would/could do this, at least at a reasonable price. Besides, it probably wouldn't increase battery life very much anyway, since there usually isn't much wasted space in a flashlight.
I get what you're saying. Would be neat but I figure if the battery went bad you'd toss the light instead of replaceing the battery. Kind of like a lot of things now a days that aren't user servicable. Like a BMW drive shaft... you can't buy a new U joint and bolt it in, you gotta buy a WHOLE NEW drive shaft. /ubbthreads/images/graemlins/frown.gif But you could take it to a machine shop to have them cut/weld a new one in... If only you could just bolt a new one in...
Get what I'm saying... heh. Not for me!! /ubbthreads/images/graemlins/smile.gif