A method of registering a plurality of Battery-Monitoring-Units (BMUs) in a battery pack with a Battery-Management-System (BMS), the method comprising: providing an indication to a user, wherein the indication prompts the user to register one of the BMUs with the BMS; the user performing an action on a communication-initiating mechanism on one of the BMUs, wherein the communication-initiating mechanism is configured to initiate the sending of a communication by the BMU to the BMS in response to the user performing the action; the BMU sending a communication to the BMS in response to the user performing the action on the communication-initiating mechanism; the BMS receiving the communication from the BMU; and the BMS registering the BMU in response to receiving the communication from the BMU.