Abstract: A retrofitable drive assembly attaches and detaches quickly, easily, and reversibly from a conventional, manually powered wheelchair and is employed to convert the manually powered wheelchair into an electrically powered wheelchair. The drive assembly includes a plurality of wheel troughs, each adjustably sizeable to receive therein a rear push wheel of the manually powered wheelchair, regardless of the wheelchair's size and its rear push wheels' dimensions. In addition, the drive assembly includes two drive wheels positioned towards a front end of the drive assembly and a single caster-wheel assembly positioned towards a rear end of the drive assembly.