Energy conservation is one of the most fundamental and well-established principles of physics. E. Noether extended the energy conservation principle to the quantum field theoretical domain in empty space by relating the time-translation invariance of the universe with energy conservation. While this is the case in an open empty space, it seems that the local space enclosed by conducting metallic plates has an unexpected property, suggesting that the energy conservation principle may not necessarily apply to localized bound systems of capacitors in electrodynamics. This point of view was raised by noting that the spherical capacitor has calculable electrostatic self-potential energy in both the inner and outer shells, which is not considered in the conventional consideration of the total energy stored in the capacitors. It seems that the concept of moving charges one by one into the capacitor plates has helped bypass the necessary steps to account for the additional repulsive self-potential energy that accumulates simultaneously in both capacitor plates in the process of charging the capacitor. We present the itemized details of the repulsive potential energy stored in the capacitors and discuss its physical reality in relation to the anomalous energy devices reported in the past.