I want to understand exactly how an MPPT charge controller works and all I could find is this:
An MPPT charger is a DC-DC transformer, that when it lowers the input voltage, it raises the output current as well, therefore, except for a small loss, the input and output power is the same.
But I also know that a battery bank needs to be charged in different steps having different voltages and currents (bulk, floating, ..etc)
So my question is that, if the MPPT charger always tries to get the most current out of the panel, how does it achieve those different charging steps?
Also, most references say that the output voltage is constant, so the control is done on the current, i.e. the output current is constantly compared to the maximum value and it alternates around a maximum reference value. How is the voltage constant - doesn't the battery voltage also change when the bank is charged and discharged?