I just needed to do something quick and simple today. Now, the batteries in the Nokia decrease gradually across time. You can pick up battery packs in the map which spin and glow which charge your batteries back up again. I haven't decided what happens if your battery dies - I think you'll loose access to the map/additional help and won't get messages? Not sure yet, we'll see.
If I don't do this then I'll do nothing and it'll all be boring again. I'm trying to find stuff I love to do, I used to do a lot of this stuff and now I want to do it again.