⭐⭐⭐⭐⭐ "Survival Energy when you NEED IT."
Keeping your electronic devices fully charged is Prepping 101.
If the grid goes down, or even if you just forgot to charge your battery, you could find yourself in a hopeless situation.
Imagine if you were in a car accident...
Or twist your ankle while hiking in the wilderness...
Or you're lost in a bad part of town...
And suddenly your phone battery is dead.
No more connection with the outside world.
Even if you don't have cell reception, having a charged battery means you can still be found through satellite triangulation. But that technology is useless if your battery's dead.
You could probably live with yourself for not being able to contact help. But could you live with the fact that having a dead battery could also mean not being able to communicate with the ones that mean the most to you... at a most critical time?