The Sony RX-1 has a small battery; it looks like the designers decided to double down on small size and light weight. There have been some complaints — although non from me — about the RX-1 battery life, which has usually been enough for me to make 400 or 500 images. I use a 1600 mAh aftermarket battery rather than Sony’s 1240 mAh battery.
Then I got the EVF. Now I get a thousand or so images from a fresh battery. It seems that the EVF doesn’t take as much juice as the LCD on the back of the camera. Using the built-in flash and chimping will affect the battery life, so YMMV.