Originally any engine for discharging missiles (catapults, slings, bows, etc.); modern restriction to "ordnance, large guns" is from 16c. Technically, "all firearms discharged from carriages," as opposed to small arms, discharged by hand. As a branch of the army, from 1786.
type of cast-iron smooth-bore naval artillery cannon, by 1854, named for its inventor, U.S. naval ordnance officer John A. Dahlgren (1809-1870), who was of Swedish ancestry.
1530s, "action of battering," in law, "the unlawful beating of another," from French batterie, from Old French baterie "beating, thrashing, assault" (12c.), from batre "to beat," from Latin battuere (see batter (v.)).
Meaning shifted in French from "bombardment" ("heavy blows" upon city walls or fortresses) to "unit of artillery" (a sense recorded in English from 1550s). Extension to "electrical cell" (1748, first used by Ben Franklin) is perhaps from the artillery sense via notion of "discharges" of electricity. In Middle English, bateri meant only "forged metal ware." In obsolete baseball jargon battery was the word for "pitcher and catcher" considered as a unit (1867, originally only the pitcher).