Can a capacitor be charged using a DC motor and if yes how?
I think you mean DC generator, and the answer is yes. Motors convert electrical energy to mechanical energy. Generators convert mechanical energy to electrical. Of all the DC motor designs, only permanent magnet ones can function as a generator. How? first of all, the output voltage of the generator has to be less than the rated voltage of the cap. Then just connect it and spin the generator. There are two leads on the cap, + and –, and two on the generator, also + and –, and you do, I hope, then know how you connect them.
You must realize that you use an energized solenoid to generate energy and power to charge the capacitor (say 100 uF) when using a DC motor. In this case, the solenoid when not energized (when the motor stops rotating) would present a low resistance short to the charged capacitor. To prevent the capacitor being discharged as above, use a rectifier diode (1N 5408) in the circuit.
Yes. Observe Voltage polarity, if the capacitor is an electrolytic, and connect the two through a Voltage dropping resistor large enough in value to form a relatively long time constant. I think the internal resistance of the the DC (motor ? generator?) plus any series Voltage dropping resistance would form a time constant with the charging capacitor and after 5 time constants have the capacitor charged to about the open circuit value (EMF) of the DC source (generator- motor). I have never charged a capacitor in this manner so I am only making what I consider a logical guess.
DC MOTOR PROVIDES VERY SMALL VOLTAGE AND CURRENT BECAUSE IT IS NOT A PROPER DESIGN TO BE USED AS A DC GENERATOR !! TO CHARGE A CAPACITOR WITH IT IS QUITE SIMPLE AS FOLLOWING..... DC MOTOR POSITIVE TERMINAL ------> CAPACITOR POSITIVE TERMINAL DC MOTOR NEGATIVE TERMINAL ------> CAPACITOR NEGATIVE TERMINAL. ROTATING MOTOR NON STOP FOR AT LEAST A FEW MINUTES TO CHARGE A CAPACITOR HAS ABOUT 1000uF CAPACITANCE. AND BE SURE TO DISCONNECT CAPACITOR FROM MOTOR WHILE MOTOR IS STILL ROTATING WHILE YOU THINK THE CAPACITOR IS ALREADY FULLY CHARGED, BECAUSE IF YOU DISCONNECT THE CAPACITOR AFTER MOTOR IS FULLY STOP, THEN ALL THE CHARGE SHALL BE TOTALLY DISCHARGE BACK INTO THE MOTOR COIL.