Secon battery monitor

Hi. I have diy x8 octo. I have dual 6s 10000mah lipo and 3s 2200mah lipo. I will use 3s lipo with 3dr power modul for gimbal etc… But I dont know wiring battery to pixhawk ADC 13pin, 14pin, 15 pin or otherway. I use copter 3.4.6 and. I see battery monitor 2 on miision planner secreen. Help please. Sorry for my bad english.