A battery pack is an enclosure consisting of one or several cells, safety component(s) and cell monitoring electronics. A pack used in smartphones typically consist of one cell, a protection circuitry and a secondary safety component (e.g. fuse or PTC). The protection circuitry ensures that the cell voltage and current limits are not exceeded in any conditions. A pack used in electric vehicles may consist of hundreds of cells, connected in series and also parallel to facilitate both high voltage and high current. A Battery Management System (BMS) is required to ensure that each cell block in series connection stays within safe limits. In addition, BMS is used to balance the voltage level of each cell block in series connection.