Question Сonnector for charging

[Linet]

Hello all! I have a laptop HP, I need to understand what is the connector for charging, where can I see it? There is nothing marked on the laptop itself. As far as I understand they come in several kinds (HP pavilion g6, dv6, dv7, 15, 17 and others. With a round plug and a needle in the center) but how to understand which one I have?
I would appreciate your help!

 

[Lutfij]

HP have a multitude of laptops in their portfolio both new and old(discontinued). Which one do you own?

 

[Linet]

I have an HP 250 G7. I want to buy a power bank for my laptop to be able to work outside the home.

 

[robert600]

I'm not at all sure what you mean by a power bank? Do you mean a plug in the wall power supply or do you mean something that requires no external power?