N135F2DC: Battery Solution: I would like to call everyones attention to this video by David Oaster in Australia. And he has some really good videos that are of interest to all Sony users. Copy and past this into your address line.
It's not something I'd need to travel with, it's just more convenient in the studio or for long stints of shooting video from a tripod. I carry 7 batteries for the 2 cameras when I travel. This allows for two days use with three spare so I have more than enough to cover during recharging.
Once you've used mirrorless you get into a habit of being more careful with your battery usage and now, it's not something I give a second thought to. I can easily go out for a full day in the mountains, one fresh battery in each camera and carry 2 spares. I rarely have to use the spares and shoot approx 300 images plus 20-30 footage clips on top. It would be nice to have a more powerful battery but it's low down on my "Wish list" in terms of how they may improve the A7rii in the future.
Tony's right. I use a 21,000+mah power pack that is equal to about 20 batteries. I use this for long studio shoots (when tripod mounted) and for shooting video. Especially video as that can use up a lot of power. It's worth buying a couple of them (£25 each) as they do take a while to recharge.