Well put! A little brain salad surgery never hurt, as long as you're careful, and it works.



Definitely do not mix mah (mili amp hour rated) batteries, it's wrong and it's dumb. You should be ashamed.
Well, not really, but it works LESS well than the lower mah rated one because of electrical inequalites when charging.

Whenever possible you want new matched pairs (or whatever). Used matched ones are okay too, as long as they are the same mah rating.