Here is informative content regarding the , typically associated with solar charge controllers (often branded as HQST , Renogy , Eco-Worthy , or similar PWM controllers). Note: Always verify your specific device label. "QP3-12a" usually refers to a 12A PWM (Pulse Width Modulation) charge controller for 12V battery systems. 1. Terminal Identification (Standard QP3-12a) The controller has 6 labeled terminals arranged in two rows. From left to right: