Green’s Dictionary of Slang

1. (Aus.) an illicit device used by jockeys to give a racehorse an electric shock and thus increase its speed .

1954

Sun. Mail (Brisbane) 7 Feb. 23/1: Batteries are as much a part of the everyday equipment of most of the older jockeys riding in the country as are whip and spurs.

2. (W.I.) a man who uses a performance-enhancing drug during sexual intercourse [he ‘charges his battery’].

1995

Francis-Jackson Official Dancehall Dict. 4: Battery [...] 2. a lone male using performance enhancing substance during intercourse.