Hey guys, I recently conducted an experiment which involved charging a battery via a PV module and also logging the I and V values to calculate conversion efficiencies. I also logged the I and V values from two other circuits with a fixed resistance. I understand that every irradiation has a Maximum Power Point (MPPT) so a fixed resistance will never draw the maximum energy yield from the PV module. But when I saw the results I saw that the power conversion for the battery was good under high and low irradiances. My question is why is this? Does a battery have some sort of control circuit to vary its resistance ? Thanks in advance.