It would be great to think about a battery plate to cover all power needs (camera and all accessories).
cine batteries cost about 2€ + per Wh and cheap battery packs for eg. sony bp-u series cost only 0,5€ per Wh.
I think we should use an existing system with a wide variety of 3rd party producers and make our own plate which manages our different voltage needs. like this example but smarter and more solid.