Hi,
I hope this thread will be helpful for debugging purposes.
I'm using the latest Mekanism stable build, and I'm building an electrical power net on a minecraft map. I built a solar power farm with some Advanced Solar Panels and Ultimate Cubes that store producted energy and give that to the net. After some days, I noticed some cube decrease their energy without attached loads.

The cubes are connected to a long universal cable line that I'm building, but he's not connected to nothing: randomly, one of cubes started to decrease his amount of energy. If i break the cube cable, the cube will continue to release energy!

I think I'm doing some mistakes, but try to check this screenshots:
The buggy cubes is the disconnected cube.

Can be this an issue?
Ask me all informations you need (:

The cable are not green because I disabled the fancy graphic from the mod settings

This is normal! The cubes are still connected to single cable units which can store a buffer of power. The fancy graphic would visualize this.