Eli5: How does a power bank charge a device until it dies, wouldn’t equilibrium be reached?

Question

Eli5: How does a power bank charge a device until it dies, wouldn’t equilibrium be reached?

In: 551

Answer 1

Power for most devices are one way for power. Power bank has an output and the phone has an input. If you plug two phones together they don’t charge each other. It’s like filling a toilet tank there is a valve (Transistors) that stop the flow when the receiving device is full.