This is where my iPhone's battery was at 10:20PM tonight. I had taken the phone off the charger around 10AM that morning and had been using it sparingly throughout the day. Since I hadn't used the phone much, I didn't have a good idea of how my battery life was doing. On days like this where I have to work late, I have not always gotten this far with this much juice still in the tank. Having over half my battery left was amazing!
It was amazing not because it meant I could use my phone a lot more, but because I could choose to ignore it if I wished. I still had an hour;s drive home and needed the phone to make it though that journey. If I was sitting at 10% battery, my mind would immediately shift to thoughts of "where can I charge this thing now?" and "can I make it all the way home?" Neither of those thoughts help me in any way get my actual work done. In fact, they distract me from the tasks that I have to get done.
People who talk about productivity always talk about "friction" and for good reason. When it comes to smartphones, batteries are still a huge point of friction for a lot of people. I don't love the Samsung commercials, but they do have a point. When you're thinking about or tending to your smartphone, you're wasting time and mental cycles on this silly rectangle in your pocket.