I am using the above circuit to charge a 7.4V Li-ion Battery.With input MPPT voltage set at 12V, I have applied 13V input voltage to the circuit. The battery is charging at 1.4A. (according to the calculation it should be 2A). But, the input diode D1, Input capacitor C1, MOSFET Q1, diodes D3 and D4, Inductor L1 are heating too much during charging. What could be the reason of heating ? Any design problem or other?
C1 looks backwards on your silk screen (certainly its the other way wround from C8). Is it possible you've fitted it back to front and it's drawing current and getting hot? That current would also heat D1, and the lack of decent decoupling would then put more stress on Q1 D3,D4 and L1 making them hot.