Just a forewarning I am a complete rookie when it comes to capacitors
I am looking to supply a 0.5mV charge into a capacitor, then have the capacitor discharge to a battery once the accumulated charge reaches 4V. Once the stored charge on the capacitor is below 4V, the capacitor should store the energy again until the accumulated charge reaches 4V to repeat the cycle listed above.
So basically I am looking to have a low voltage input into a capacitor, and have the capacitor discharge to a battery only when the stored charge is above 4V. What type of circuit is capable of this task? Will just a super capacitor work?