A drive arrangement (1) comprising an input (2) from a primary power source (5) and an auxiliary power source (7). The drive arrangement (1) incorporates a DC-DC converter (8) and a motor driver circuit (14). The motor driver circuit (14) is connected to a motor (18) in a motorized seat belt retractor. The drive arrangement (1) drives the motor (18) in the event of a crash situation. If the connection between the drive arrangement (1) and the primary power source (5) is lost then the drive arrangement (1) draws power from the auxiliary power source (7) to drive the motor (18). The auxiliary power source (7) can also assist the primary power source (5) by limiting the current drawn from the primary power source (5).