DIY Mac powerbank

[ItsMinJunLol]

Hi! I want to build a powerbank that can charge my mac air. My mac air accepts 14.85V at 3.05A max. I'm planning to use 8 25R 18650 cells(with BMS), a variable current and voltage controller, a volt + ammeter for monitoring purposes, and a mac charger.

 

I have a few questions.I found 2 that can be used as a variable current + volt.

One uses a XL4006 (Link) and can output 1.24~32V and 5A max (step down) with a input voltage of 5~36V and the other one uses

some capacitors, transistors and a coil. (LINK). It can output 1.25~30V with 5A continuous current(24-7)

 

They both seem good options, but I personally think the 8A one seems a bit shady but yeah, I'll have to see.

 

My second question is about batteries. I think samsung's 25R 18650 batteries are good because they can have 20A of continuous current with 2500 mah capacitance. I will have a 4s pack of these with 2 rows, effectively creating a 14.4v 5000 mah battery.

 

My third question is how does a magsafe charger work? I can make this powerbank, but if apple's magsafe's charging methods are different than any other normal charging methods, then I can't build this. 

 

I hope someone can answer these questions and if you can, thanks in advance.