Battery life of Video assist 12g 7" vs. 5"

Does anyone have experience comparing the battery of of the 7" and 5" versions of the Video Assist 12g?

What I'm hearing about the 7" isn't very encouraging. Doesn't seem to last more than 30min max. Is this correct? Is the 5" version any better?

Keith Sanborn

How would you be using the BMVA12G7/5? Battery life will depend upon:
ambient temperature?
how would you power the video assist?
brand of batteries?
number of batteries used at full-strength?
screen brightness?
monitoring and recording or not recording?
working with 1080p or 2160p?
recording to internal or external media?
codec flavour used for recording?
frame rate?
passing data through to other devices?