A Pelican style Block battery is SOOOOO easy to make it's retarded. I made a ton a few years ago with built in chargers for less than $100 a peice. The problem here is that until Red has some kind of voltage monitoring system It's impossible for the camera to know the batteries condition so the camera can shutdown without warning.
Hi Mike
PM me please as I want to talk to you further about this and a few other things.
cheers
D