power bank functioning for battery charger

[kg_anjana]

hiii
please anyone help me by explaining the functioning of power bank...i have a doubt , how 2800mAh power bank is used for charging 2200MAh battery by completely draining out itself... i stuck with the idea that current flow is from higher potential to lower until both are at equal potential...if it so, then how a power bank is working by completely draining out itself....
help me please
Thanks in advance

 

[Audioguru]

Does the "2800mAh power bank" have a high enough voltage and have a charging circuit for charging your 2200mAh battery?
You did not say the type of battery so it might be a 3.7V single cell of Lithium that is 4.2V when it is fully charged and is about 3.2V when it should have its load disconnected. The power bank might have a voltage stepup circuit and a battery charger circuit.

- - - Updated - - -

I looked at "power bank" in Google. It does not charge a battery, instead it supplies 5V power to a cell phone and the charger circuit inside the cell phone charges the 3.7V battery inside the cell phone. Some power banks are charged from an AC wall outlet and others are charged from a 5V USB jack in a computer.

 

[ArminVanBuuren]

Does the "2800mAh power bank" have a high enough voltage and have a charging circuit for charging your 2200mAh battery?
You did not say the type of battery so it might be a 3.7V single cell of Lithium that is 4.2V when it is fully charged and is about 3.2V when it should have its load disconnected. The power bank might have a voltage stepup circuit and a battery charger circuit.

- - - Updated - - -

I looked at "power bank" in Google. It does not charge a battery, instead it supplies 5V power to a cell phone and the charger circuit inside the cell phone charges the 3.7V battery inside the cell phone. Some power banks are charged from an AC wall outlet and others are charged from a 5V USB jack in a computer.

Could I ask?

Is this process identical to charging? IE standard charging is the same as "instead supplying 5V power to a cell phone and the charger circuit inside the cell phone charges the 3.7V battery inside the cell phone"?

Or those two are not identical, and the second (supplying 5V from power bank) can even damage the battery / phone charging circuit?

Thank you

 

[Audioguru]

The power bank has a charger circuit inside to charge its Lithium battery from a 5V source.
It also has a voltage stepup circuit and voltage regulator inside so that its 3.2V TO 4.2V Lithium battery powers it for its output to be 5V.

 

[ArminVanBuuren]

So it's completely the same as if charging from the wall?

No damage can occur to the battery / phone electronics?

I consider this power bank:

**broken link removed**