Solar Power to Traction Pack Fan ?

I've started using a 5 W, Harbor Freight solar panel designed for tickle charging the 12 V. to power a small, squirrel cage fan in the window to exhaust cabin heat. But I need to add another circuit.

The variable power supply of the solar cells means it often has voltage but not enough current to handle the motor startup load. What is needed is a storage device, capacitor or battery, to accumulate the power with a load controller with voltage hysteresis:

• charge a big cap to ~14-15 volts
• discharge cap into load with solar still connected
• turn load off at ~9 volts so cap recharges

I've sketched out a circuit that uses a MOSFET, bipolar transistor, zener and resistors to be a solar, hysteresis controller. However, there are alternate designs. It would be an excellent assignment for students. Give them some design constraints for extra credit. <grins>

Bob Wilson

 

If I was a student, I would cheat and Google it...This circuit might help.


You might want to put a big capacitor on there to handle the surge.

I have not tried this out yet.

A simple solar panel regulator

 

I actually had the same idea, I even posted about it on here several months ago. But I never got around to trying it.