I like the C40 because it can be used in 3 different modes:  Solar Cell (PV Photovoltaic) charge controller mode, (2) Charge Diversion controller, and (3) LVD Low voltage drop out controller.  

I bought one of these and tried to hook it up to a pedal power bicycle generator  in the 1st operating mode  (Solar Cell Charger Mode).  It was connected between the bike generator and the capacitor as shown in the diagram below.  The capcitor was connected to an AC inverter which was providing power to a 100 Watt light bulb.  When I change pedaling speed from slow to fast, my voltage going from the bicycle generator into the C40 controller changed from ~13VDC to ~18VDC.