Portable DC Power Supply with Adjustable Voltage

DIY Portable DC Power Supply with Adjustable Voltage (3-28V)
Wanted to make one to use on the go or when my bench supply is hooked up to something else.

Instructions: https://www.youtube.com/watch?v=tS9OZw_sj4k

Min voltage: Battery voltage (3.0 - 4.2V)
Max voltage: 28V
Max current: 2 Amps
Capacity: About 4800 mAh (Depending on battery condition)


Bill of Materials
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2x 18650 Batteries (wired in parallel)
1x TP4056 Li-Po charger with protectio