Megajoules

1 MegaJoule is equal to 1000 ElectricCharge.

All of the components in this mod produce or consume energy in quantities that are quite large compared to the ElectricCharge used by the stock parts. While the mod could simply use large values of ElectricCharge, using a separate unit gives the mod a way improve the way some components consume energy, allowing very thirsty items like the Alcubierre Drive to consume as much energy as you want to feed it, but without starving other components.

To maintain compatibility, any component that produces MegaJoules will first check to see if there is any demand for ElectricCharge. It will satisfy this demand first, and then use the rest of it's power to produce MegaJoules. Parts that require MegaJoules to function, however, will not draw from the available ElectricCharge even if you have enough. Some examples may be in order:

many solar panels → plasma engine

Does not work; plasma engine requires MegaJoules, solar panels produce only ElectricCharge.

many solar panels → microwave power transmitter → microwave power receiver → plasma engine

This works, provided the receiver/engine is on another ship.

Electric charge is needed to produce megajoules, the amount is proportional to the time taken for the electric charge to run out. This means you may need a significant amount of batteries to produce usable amounts of power when using gigantors in low Kerbol orbit

nuclear reactor → electric generator → spotlights

This works just fine; the generator will produce gobs of power and convert a trickle of it to ElectricCharge to power the lights.

nuclear reactor → electric generator → science lab + spotlights

also works; the generator will produce slightly less power for the science lab.