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An Apogee with approximately 40% hard flux and an additional 20% soft flux.

Flux is one of the fundamental concepts in Starsector combat. It resembles heat in that firing and receiving strikes to shields produces flux. Each ship has a certain maximum flux above which it will overload and be helpless for many seconds. Balancing flux is one of the most important skills to develop in combat.


Flux is shown as a bar above the hull rating, both in the bottom left HUD and in the info directly above a ship. Weapons will not fire if a ship's flux is full or if the flux from the weapon would fill it.

The flux bar slowly falls with time because ships are always passively dissipating flux into space. Ships can vent flux at twice the normal dissipation rate (press the 'V' key) but meanwhile cannot fire weapons, use shields, or stop this active venting until all flux is vented.

On the Refit Screen, ships can be fitted with additional flux capacitors to increase their maximum flux by 200, or flux vents to increase flux dissipation/venting rate by 10. Several skills also improve flux dissipation/venting and capacity.

A ship with an empty flux bar and not generating any flux (this requires shields to be down) will gain a zero flux speed boost that raises its maximum speed by 50 su/s. The Dynamic Stabilisation perk of the Helmsmanship skill allows the bonus to apply at up to 1% flux (including with shields up). The speed bonus always applies when a ship has the Safety Overrides hullmod installed.

The Resistant Flux Conduits hullmod increases venting speed by 25%, and the Dedicated Conduits perk of the Power Grid Modulation skill increases it by 25%. The Safety Overrides hullmod doubles dissipation speed (including from vents) and disables venting.

Hard flux and soft flux[]

Flux from firing weapons, using shipsystems and keeping the shields up is known as soft flux because it can be passively dissipated with shields raised. Flux generated by the shields being struck is known as hard flux because raised shields (normally) prevent passive dissipation. A vertical bar in the flux gauge denotes the boundary between hard flux and soft flux in the flux capacitors. Soft flux always dissipates before hard flux.

Phase cloaking produces hard flux upon activation and during use, and prevents hard flux dissipation.

The Defensive Systems skill level 3 allows gradual passive dissipation of hard flux with shields raised. The Flux Shunt hullmod has a similar but greater effect, but is only found built into a few ships.


Firing cannot raise flux above the maximum, or overload a ship, but shield strikes can. An overloaded ship cannot raise its shields, fire, use ship systems, or actively vent, but it will passively dissipate at half its normal rate and maneuver as normal. The overload lasts a number of seconds (up to 15) depending on the damage dealt by the last hit. An overloaded ship is extremely vulnerable to missiles and strike weapons.

Level 3 of the Damage Control skill in the combat tree reduces overload duration by 25%.

Change History[]


  • Weapons will not reload for the first two seconds of venting or being overloaded