Q: Er, why not use 5x1.5V batteries in place of 6x1.2v (or more properly 6x1.25)? That would be a very close 7.5V vs 7.2~7.5, and it's not exactly difficult to just bridge the empty slot with a random piece of metal (bar, foil or wire)...
I've done similar before in creating a battery pack for an old MP3 player ... cheap Maplin battery box, and a dummy battery (straight piece of metal to bridge the terminals) that can be put in when using alkalines rather than ni-cads in order to not toast the charge circuit... 18.104.22.168 02:13, 20 February 2012 (PST)
A: Because 1.2V is the standard for rechargeable AA-batteries and because those batteries are available cheap and environment-friendly. So there's no need to fiddle around with battery boxes, soldering-irons, ... once you've found the original holder for rechargeable AA-batteries. --Jpolzfuss 03:07, 20 February 2012 (PST)