The Ultimate Energy Cube is a machine added by Mekanism. It is the highest tier of energy cubes. It can store and output more energy than the Basic, Advanced and Elite Energy Cubes. Furthermore the Cube can be used as a charging station for items.
In addition to the cables from Mekanism (e.g., the Basic Universal Cable), the cables of all supported power systems can also be connected. So the Cables from IndustrialCraft 2 (e.g. the Copper Cable), the Fluxducts from Thermal Dynamics (e.g., the Leadstone Fluxduct), and the Kinesis Pipes from BuildCraft.
With a right-click on the block the player can open the GUI of the cube, which shows the internal storage.
Inside the minus slot the player can place other loaded energy cubes to load the placed cube.
The upper-left button (called "Side Config") opens the configuration of the cube, where the player can set which side should receive or emit energy. If a side is disabled, the center of the side is transparent and no cable connects on this side. If the player holds the Configurator in theirhand, the cube displays a color code on the side the player is looking at. Grey means "Off", red means "Output," and blue means "Input". Shift right-clicking a side will change its configuration.
The lower-left button changes the displayed energy system between Energy Units, Redstone Flux, Minecraft Joules, and Tesla. The change only affects the display; the energy is still available in all forms inside the system.
The upper-right button configures the access rights for this block.
The lower-right button changes the Cube's behavior to Redstone. For example setting its behavior to respond to "High" Redstone input will release energy when a redstone signal reaches the Cube.