Big screens and big batteries: what's the best combination?

So the larger the screen (and resolution) on your smartphone the bigger the battery you need to keep it running.

Huawei has popped an awesome 4,100 mAh battery in their Ascend Mate 7, which is a massive 6-inch device. But because it is only a Full HD display the battery life is pretty phenomenal.

Lenovo put such big batteries in their phones that you can actually charge other phones with theirs (the Mate 2 could also do this).

So what's ideal? How big does a screen have to be? What resolution is optimal? Just how big a battery do you need? Remember that the battery is the biggest part of a phone and it also adds to the weight, so getting the balance right between run time, weight, cost, screen size and resolution is a tricky business.

What do you think we should expect from batteries and our phones?

As much as I like QHD displays, I'd almost prefer a Full HD offering that can run for several hours longer. I'm still out to lunch on the weight issue, because I often use battery packs and hate the additional weight, but at least I can leave that at home if I feel like it. I don't know how excited I am for a much better battery if I have no choice but to lug it around in my jeans.