From Halopedia, the Halo wiki
A plasma battery is a form of Covenant power cell. They were used by the Covenant to power all forms of equipment under the size of a capital ship or citadel. Plasma batteries encapsulate high-energy plasma in a containment cell and could be recharged from generators. Plasma batteries vary wildly in size and shape, but are among the most standardized components used by Covenant technology and have remained relatively unchanged in function for several centuries. They rely on internal mechanisms that are both arcane and highly dangerous to replicate.
The Vantus-pattern eolipile is a prominent type of plasma battery distinguished by its triple-pronged shape. They were widely used by Covenant ground forces to recharge their weaponry and vehicles on the field. They were lightweight in construction and could be recharged at almost any generator, but their lack of shielding made them quite vulnerable to damage and explosive containment failure.
Plasma furnaces were small, high-output plasma batteries used by the Covenant for specialized applications, such as Sangheili combat harnesses and deployable shields.
In-game, plasma batteries are essentially the Covenant equivalent to the UNSC Fusion coil and the Forerunner power core. They require more shots than the fusion coil to explode. They also require a higher drop to detonate them on impact. It takes two explosions from a plasma battery to kill a fully shielded SPARTAN-II or Sangheili.
They appear in both campaign and multiplayer, and can be very useful to whomever sees the right moment to detonate it, such as near a pack of Grunts. These can also be bought when in Forge, costing a fair price. They can be placed anywhere on the map, even in mid-air. If in a last-ditch situation, you can kill enemies standing near either a plasma battery, a power core or a fusion coil by shooting at it. Any enemy killed using the explosion from a plasma battery will be listed as killed by you using an "Unknown" weapon. It appears to have energy shields as part of its structure, however, you don't need to deplete them to detonate it. There are stacks of them on the Halo 3 level, The Ark, and can be used to kill nearby enemies. Once one explodes, it causes a chain reaction of the explosions of nearby plasma batteries.
The Vantus-Pattern Eolipile as it appears in Halo 3.
A Vantus-Pattern plasma battery on Snowbound.
The Vantus-Pattern Eolipile in Halo: Reach.
Other Covenant batteries
A Covenant battery in Halo 2.
A plasma battery next to a Covenant recharge station.
Concept art depicting various Covenant plasma storage devices from Halo: Reach.
Concept art of a Covenant battery for Halo 2: Anniversary.
List of appearances
- Halo 2 (First appearance)
- Halo 3
- Halo 3: ODST
- Halo: Reach
- Halo 4
- Halo: Escalation
- Halo 2: Anniversary
- Halo 5: Guardians