I found a video where the guy was chatting on 6m SSB for just under two hours using the 705. The battery life was the point of the video. He kept the screen on during the test. I am not sure of his screen brightness level, but per the manual it defaults to 50%. He's outdoors, so I am unsure if he changed it for visibility on the camera. If I come across a test video or information of how much power the screen draws I will update.