Jan 31

Energy harvesting from soccer ball

Max is using piezo-electric transducers to convert the energy from kicking a soccer ball into electricity, potentially useful for lighting or cellphone charging. Piezos produce high voltage and low current in one polarity when flexed and then in the reverse when the flex is reversed to return the piezo crystal to a neutral position.  To capture this energy, Max runs the electricity from the piezo through a full-wave bridge rectifier and to a polarized electrolytic capacitor.  The bridge prevents reverse-voltaging the capacitor as well as the capacitor discharging through the piezo.

Photos show Max wiring and testing the circuit, soldering and testing it, and then mounting it in a soccer ball.  He placed the piezo just under a ball flap he cut away, where a kick would flex it.  He drilled a hole to the center of the ball for wires to attach to the bridge and capacitor.  Max hollowed out a cave in the ball center to hold this electronics.  Two more wires run from the capacitor out of the ball for testing and, eventually, energy recovery.

Testing showed progressively higher voltages across the capacitor with each flex of the piezo, which he flexed by thumb.  Next steps: testing efficiency of mechanical to electrical energy capture and how much energy can be captured.

working outdoorswiring circuitsolderingpeeling panel from ballclosing panel inserting piezo behind paneltaping leads energy storage inside ballIMG_3641 (1)flexing piezo in ballflexing piezo under panel


measuring voltage from flex
voltage from piezo

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