I have been taking some foil and various "dielectrics" in attempt to build a capacitor. The best I have done so far is an extremely low capacitance (potential difference drops fast even on reading voltage with great resistance) where I will get about 3v for a few milliseconds after having charged with a 19 v battery pack. Really though, no matter the capacitance, I should be able to get the same potential difference. I am thinking this is not the case because the plate separation to plate area ratio is too large. If I were to decrease the distance, would I then be able to get a closer potential difference to that of the supplier (battery)? Or that is; does the potential -> battery potential as separation distance -> 0? Also, would saran rap be a good or bad dialectic material considering it stores charge quite well?