MorningStar TS45

ewarnerusa wrote:
I'd say it is duty cycle. Essentially the inverse of how much clipping the solar controller is doing to prevent the battery from exceeding the charging setpoints. During bulk charging, the duty cycle is 100% because the controller is allowing all of the solar current input to reach the battery. Once your absorption charging setpoint is reached, the controller begins to taper the current by decreasing the duty cycle (increasing the off time of the on/off PWM cycle) so that the absorption setpoint voltage is maintained. This is why you see that number fluctuating. As sun comes and goes and as battery SOC increases, the controller will do what is necessary with the duty cycle to allow the battery voltage to remain at the absorption setpoint. The Trister PWM will transition from absorption to float based on time at or below a preset duty cycle percentage.