To double rooks on a file, or to place a bishop and a queen on a diagonal. In chess problems, battery refers to an arrangement of two pieces in line with the enemy king on a rank, file, or diagonal so that if the middle piece moves a discovered check (or a threat other than a check) will be delivered.

Lining up two pieces that move similarly, like a Queen and Rook or Queen and Bishop.

A lineup of pieces that move similarly on a single file or diagonal, usually pointing toward a critical point in the enemy's camp. Batteries can be created by Queen and Rooks on a file or rank, and Queen and Bishops on a diagonal.