Military weapons are indeed likely the source of the term 'battery'. Ben Franklin coined the term in reference to arrays of Leyden jars. Presumably, this was for experiments where he would 'load' the capacitors, and then quickly 'fire' (discharge) them, resulting in a spark of some kind (which probably is what led him to suspect that lightning was electrical in nature).

http://www.etymonline.com/index.php?term=battery