One variation of a system includes a kit including: a driven axle configured to install on a trailer; a motor coupled to the driven axle; and a battery assembly configured to install on the trailer. The battery assembly includes: a set of cross members; a set of batteries arranged between the set of cross members; a set of clamps; and a set of fasteners. Each clamp in the set of clamps is: pivotably coupled to a cross member in the set of cross members; and configured to couple the battery assembly to a pair of adjacent beams of the trailer to suspend the battery assembly below the trailer. Each fastener in the set of fasteners is configured to: extend through a cross member in the set of cross members; and couple a clamp, in the set of clamps, to the cross member.