# How to connect a small PV and a wind powered motor to a rechargeable battery for educational demos?

I wish to connect a couple of small photovoltaic panels and a small motor used as energy generator to a small battery. I found these components:

Rated power: 0.55W
Output Voltage:0.01V~5.5V
Output current: 0.01mA~100mA


2x solar panels (in series). Specs for each panel

Rated power: 0.3W
Output Voltage: 3V
Output current: 100 mA (computed by myself doing 0.3W/3V)


Output Voltage: 4.8V

   Current Not sure.
I should read what is written on its charger
but I assume it should be something around 250 mA.


What is the most appropriate way to connect them?

I sketched an idea but I am not sure if it will work.
Any constructive feedback is highly appreciated.

• Depends what sort of battery. Definitely not if it's Li-ion. Commented Aug 2, 2023 at 12:50
• Ah ok, good to know. However, the battery I linked is a NiCD battery. Commented Aug 2, 2023 at 13:36
• Schottky diode drops about 0.3V. PV will be OK with 3 x NimH but motor will depend critically on actual voltage generated. || You REALLY need to decide what sot of RPM it will achieve and test it. It MAY produce more V under low load and so load down OK to suit situation. PV panel is close to a constant current source so is "happy" if loaded to a lower voltage. Commented Aug 3, 2023 at 9:25
• @Barzi2001 The generator voltage WILL vary with wind speed. Voltage at various speed will probably matter given motor voltage ratings. What rotor do you intend to use? What diameter? What wind do you expect. || Expected power is 0.6 x V^3 x A x z || V m/s wind, A area m^2, Z = efficiency 0-1 Use 0.1 to 0.2 to start. || This facebook group should be helpful. (I'm a member). facebook.com/groups/windturbinemakers Commented Aug 3, 2023 at 13:43
• @Barzi2001 The 10 Ohm resistor is not needed IF it is intended to allow the TL431 to function as a clamp. It does however reduce the TL431 clamp current to blow the 100 mA max allowed. If you want the TL431 to sink more current than its max 100 mA you can use it to drive a PNP transistor or a P-Channel MOSFET. || Examples: see this SEEE answer by Spehro . Or using a MOSFET here Commented Aug 10, 2023 at 12:00