WHERE DID THE POWERBANK GENERATION GO TO?

sometimes back last year I was at my cousin's house . I had stopped there after a long walk in the sunny city of Nairobi for a glass of water(actually it was not only water that I needed ,guess you now know)
As I am sitted on the couch sipping my orange juice in measured millimeter sips,my nephew comes in from school, he is in class two. He is so happy to see me, he runs towards my direction and jumps on me.
''Uncle where is your phone? "He asks me curiously. Without hesitation I give it to him.
"Where is your powerbank uncle? "He asks. Now my mind starts thinking , what the hell on earth is a powerbank?.
I take my phone and I text my friend Earl since he is always up to date with those kind of stuff. "hey man, what is a powerbank"the text reads like that.
A reply comes sooner than I expected
"a powerbank is a portable device for storing extra power that you use in charging your phone"
I now start wondering what this device could look like, all my mind can phototell is picture of a chloride exide battery.
I realise that I have no idea about it.
I bid my cousin and nephew bye and head towards the bus stop to board a matatu.
Inside the matatu, something draws my attention, I see the the tout with a rectangular gadget that he is using to charge his phone, on my side there is a beautiful lady,she's wearing a beutiful smile that seems to be directed at me but I wont smile back until she pays her fare.( I have fallen for that trick like three times and I ended up paying a double fare)

After she pays her fare I now start giving her that fake smile that I do keep for those kind of scenarios. She removes her phone and coincidentally she is also having the rectangular gadget connected to her phone.

I later come to learn that the rectangular thing is the powerbank my nephew was asking me about. The next day as I am walking, I see almost everyone's phone connected to the powerbank, I decide to buy mine and head straight to my cousin's house for a glass of water(I guess by now you know its not only water that takes me there).
My nephew comes from school and asks me ,"Uncle, where is your powerbank? "I proudly remove it from my pocket and give it to him.
Coming back to 2017 the powerbank things are nowhere to be seen, am about to call Earl to update me with the latest trend before my nephew does. Now this leaves me with a question, where did the powerbank generation go to?