Hey everyone, I took an electronics class not too long ago and I learned how simple circuits work So i now have a question.....I have a fan mount for my car and i found a 30mm 12v fan (used from an old power inverter). Can i simply add a capacitor on the positive side to up the voltage to 12v to have the fan spin at its normal speed? 8.4v has it spinning really slow...

Sorry, that won't work. A cap can only charge up to the voltage applied, 8.4v in this case. You'd need a switching boost regulator to get 12v, or use a seperate small (like 500mAh) 3s lipo pack.