A petrusite capacitor is a capacitor which uses the rare and valuable element Petrusite to augment its ability to store and discharge electrical energy. The petrusite capacitor can be used as a power source for a number of different electrical and electronic devices. When the capacitor is fully charged, the seven rods located under the handle become deep blue in color.
This type of capacitor appears to be the primary power source for the petrusite drills which supply power to the MSU. The petrusite capacitor is also used as a backup power supply on Helghast air assault craft, as well as on Overlord Dropships. The capacitor can also be used to provide a power supply for doors if their main power supply is disabled or cut off. Despite the Helghan origin of petrusite, the petrusite capacitor can also used on ISA intruders.