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 [[ http://de.aliexpress.com/item/For-Sony-NP-F970-F750-Battery-Plate-To-V-Mount-Battery-Adapter-for-F-V-DOF/2021852449.html | this ]] example but smarter and more solid.