Mini portable power supply 5Vcc-50Vcc

I made this portable box to feed rail relays;
The box uses a step_up modulator powered by a 4.2V 18650 lithium battery; the voltage is adjustable by potentiometer, in output up to 50Vcc; there is a button to check the output voltage on the display or the battery voltage; There is a protection circuit for the battery and for charging via micro-usb

Here's what you need:

N ° 1: TP4056 Lipo charger https://goo.gl/hiqBMV
N ° 1: Banana plug https://goo.gl/sJ7zqU
N ° 1: Battery 18650 https://g