I run only these, 1 quantum torp, and photon mines. Yet my weapon power is always drained. By looking at the stats, the weapon power drain is different. This means that they drain from each other.
Is this intentional, in which case I don't think that it is a very good feature.
If this is a bug, please fix, adn move to bugs.
...all energy weapons drain power when they fire, regardless of their type. What is the setting of your weapons power level?
Mostly this. When an energy weapon fires, if there are any other energy weapons firing at the same time, it causes a power drop by the amount listed on the weapon for the duration of the firing sequence. This design was intended to limit the massive amounts of power one could otherwise have by running an all-energy weapon layout (due to the firing cycle of DHCs, though, they only succeeded at limiting non-Escorts).