I'm quite confused about the p channel mosfet as a switch. I saw designs with zener diodes, other mosfets or BJTs but these seem overcomplicated. I have many P channel mosfets from broken chargers (mainly Alpha Omega 4407A, 4411, 4423 - which one should I choose?), that's the only reason I want to use the PMOS instead of NMOS.
I want to create a battery tester with charging and discharging capabilities. The only part that I don't know how to do is the power switching.
3V3 logic level with ESP8266 MCU, 5V charging voltage and 4.2-3V 18650 discharge voltage.