I read on another forum, some person says (read below) when you charge one cap, then discharge into another, there is 50% efficiency loss? I think this is wrong, as the only losses I can think of, are due to the caps ESR when there is a voltage difference between the caps. Can someone help show his\her Math is wrong.. Also you lose 1/2 the energy in this process. I can illustrate with a little math Given capacitors C1 and C2 of the same size (C). One charged to V and one uncharged then the energy stored is 1/2 C * V *V If you hook these two capacitors in parallel then they will settle (after a current pulse) to a voltage in each of 1/2 V. The energy in each will then be 1/2 C * 1/2 V * 1/2 V or 1/4 of the original energy in each capacitor for 1/2 of the original energy.