Modular Powerbank

If you do not have any experience in electronic and with lithium batteries, I do not recommend this powerbank for you.
For charging you will need some sort of hobby charger.

So this is a powerbank I designed for my use, I tried 210mm version with QC faceplate but it was too bulky then I switched to 120/125 mm body and I think it is perfect for daily carry (not in a pocket though).
I Used this powerbank a lot for charging my phone or for powering some diy gadgets as a Bluetooth speaker etc.
I personally used 18650 from damaged e-bike battery after reviving them they originally could discharge with current of 10 amps, I used 7.5A fuses so max output from XT-60 is just up to your batteries, use 30 Amps ones and you have a beast(just for the god sake use adequate wiring and fuses)
XT-60 output is always live, everything else is connected in series with switch
4x3Ah batteries is enough for 2 full charges of your phone, maybe a little more than that (if I calculate is as a 1S batter