What are the requirements to charge a Macbook Air? I have a 2017 13 inch MacBook Air, and I also have a big power bank. I am wondering, if it would be possible to charge my MacBook Air using that power bank. The power bank only has an output of 5V/2.4A. I am also wondering, how would you be able to find out the requirements for any Macbook device?

Thanks!
Apple publishes technical specifications for its products and are available at its website.

Have a look at: MacBook Air (13-inch, 2017) - Technical Specifications

Under Battery and Power2 it shows:


45W MagSafe 2 Power Adapter with cable management; MagSafe 2 power port


As your power bank only has an output of 5V/2.4A, which would be 12 watts, it's little more the 1/4 the output of the 45W MagSafe 2 Power Adapter that comes with the MacBook Air (13-inch, 2017). It will charge it, but it will be very slow compared to using the 45W MagSafe 2 Power Adapter that comes with the MacBook Air (13-inch, 2017).

Personally, I'd use the 45W MagSafe 2 Power Adapter that comes with the MacBook Air (13-inch, 2017), not your power bank.