About damn time!
I've been working on a AA-battery module for my old Motorola for months! The batteries fit in the space under the extended-battery caseback, but their 2.4v output doesn't meet with the phone's 3.6v expectation, so I'm trying to build a small boost converter. Except I'm not very good at it, nor am I very diligent.
Ham radios have come with AA-battery auxiliary cases for years, because we all know you don't always have a charger handy. It's almost criminally stupid that cellphones, which the majority of the population now rely on for emergency calls while traveling, don't offer a similar option. Well, I guess they do now!