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

It’s a little more like water draining from a container that’s intentionally slightly higher up. All or almost all of the water can drain into the lower container as long as the water levels don’t catch up with each other.

We just use trickery and clever design to always make sure the thing that charges is higher on the shelf than the thing being charged

Edit for clarity: height, in this case, is analogous to voltage