Capacitor is a good battery with very big number of charge/ discharge cycles. The one in your hand is just 4.7 miliF. 35v. If charged fully, it will light a LED just for a blink of time.
1. With higher and higher Farads , it becomes bigger charge storage device.
Have you ever heard of HandShake Magnet Torches ? They use Capacitors to store charge. And LED remains lighted bright for as long as 60 seconds
2. People have also used to bluff/fool the charge controller of big solar panels by adding a capacitor in place of battery that charges up and turns on the charge controller and then they use solar energy through charge controller to directly run appliances(no battery), (as long as sun is there) because through controller it becomes a regulated voltage but charhe controllers need battery to turn on.and capacitor does that.advantage is big big charge diacharge cycles of capacitor than lead acid batteries.
3. What purpose you wish to do with coil ? If you want to charge a capacitor from a coil then yes you may charge it. But with an electronic kit that make sures capacitor is not overcharge ,otherwise capacitor will jusf blow up. Coil ka kuch nahi jana ;-) its more powerful than capacitor in its make and capability.
How it can be measure that capacitor is Ower charging. .. yes I have n idea that how capacitors works. .
But someone suggest that it will put some load on coil. .
And electrician just remove that fuse that was previously installed for battery charging. .. is it okay without 10 amp fuse. ..
And why Honda and other manufacturers not using capacitors instead of battery to reduce cost. ... ???