An apparatus, comprising: (a) a handle assembly , wherein the handle assembly comprises: (i) a housing , and (ii) a first control circuit located within the housing; and (b) a battery pack assembly , wherein the battery pack assembly comprises: (i) a power supply configured to selectively transition from a first state to a second state, wherein the power supply is configured to energize the first control circuit of the handle assembly in the first state, wherein the power supply is configured to not energize the first control circuit of the handle assembly in the second state, and (ii) a second control circuit in communication with the power supply, wherein the second control circuit is configured to transition the power supply between the first state and the second state; characterised in that the battery pack assembly further comprises an accelerometer in communication with the second control circuit, wherein the accelerometer is configured to detect movement of the battery pack assembly, wherein the accelerometer is configured to instruct the second control circuit to transition the power supply from the second state to the first state in response to the accelerometer detecting movement of the battery pack assembly; and in that the second control circuit is configured to draw power from the power supply when the power supply is in the second state. (a) a handle assembly , wherein the handle assembly comprises: (i) a housing , and (ii) a first control circuit located within the housing; and (i) a housing , and (ii) a first control circuit located within the housing; and (b) a battery pack assembly , wherein the battery pack assembly comprises: (i) a power supply configured to selectively transition from a first state to a second state, wherein the power supply is configured to energize the first control circuit of the handle assembly in the first state, wherein the power supply is configured to not energize the first control circuit of the handle assembly in the second state, and (ii) a second control circuit in communication with the power supply, wherein the second control circuit is configured to transition the power supply between the first state and the second state; characterised in that the battery pack assembly further comprises an accelerometer in communication with the second control circuit, wherein the accelerometer is configured to detect movement of the battery pack assembly, wherein the accelerometer is configured to instruct the second control circuit to transition the power supply from the second state to the first state in response to the accelerometer detecting movement of the battery pack assembly; and in that the second control circuit is configured to draw power from the power supply when the power supply is in the second state. (i) a power supply configured to selectively transition from a first state to a second state, wherein the power supply is configured to energize the first control circuit of the handle assembly in the first state, wherein the power supply is configured to not energize the first control circuit of the handle assembly in the second state, and (ii) a second control circuit in communication with the power supply, wherein the second control circuit is configured to transition the power supply between the first state and the second state; <EOS>