Energy Storage Module
The Energy Storage Module is a block that can store 2.5 Mega Joules(MJ) of energy for later use. It was added in Galacticraft 2 and replaced the Battery Box from Basic Components. A Battery can be placed in the bottom slot to expand the amount of storage to a total of 7.5MJ, however a battery will not recharge in the bottom slot. The top slot can be used to charge an additional Battery. Using these two slots, you can effectively have a 7.5MJ Energy Storage Module, but it will require some micro-management switching the batteries from the bottom slot to the top and vice versa once charged.
Using Aluminum Wire connect a power source such as a Coal Generator to the green input side. Then connect the red output side to the machine requiring energy. If no energy is being consumed by a machine or if excess energy is being produced, the module will slowly charge up. When energy is no longer being produced or if the demand from the machine(s) is too great, the stored energy will slowly deplete until a sufficient power supply is present again.