[ars]

The word battery doesn't mean that. It means to beat and batter. Which is what artillery does.

The electrical meaning came much later, possibly from the electron discharges which looked like artillery attacks.

I have no idea where battery cage came from. The original battery cages were warmed with electricity - maybe an actual battery?

[vacri]

An artillery battery is an organised group of artillery pieces. It is not a single artillery piece, nor is it used to refer to the effects on the target. It's a noun, not a verb. It's "the artillery battery pounded the Viet Cong", not "the artillery batteried the Viet Cong"

A battery of chickens is an organised group of chickens. The chickens don't batter anything, and neither do the cages

A doctor might order a battery of tests on you, or a schoolkid might take a battery of academic tests - both of these things mean 'organised and related grouping' and not 'batter you down'.

The idea of organised grouping probably came from artillery battery, but in the current day, one of the meanings of battery is most definitely 'an organised, related group'.

[kalleboo]

New Oxford American Dictionary: ORIGIN Middle English: from French batterie, from battre ‘to strike,’ from Latin battuere. The original sense was ‘metal articles wrought by hammering,’ later ‘a number of pieces of artillery used together’; on this was based a sense ‘a number of Leyden jars connected up so as to discharge simultaneously’ (mid 18th cent.), from which sense 1 developed. The general meaning ‘a set or series of similar units’ ( sense 3) dates from the late 19th cent.