Abstract: The invention relates to a battery system which includes a master controller (101) arranged to determine a current control signal for controlling a charging current from a current source (102), one or more battery modules (103) comprising battery module terminals, a connection arrangement (121) arranged to electrically connect the one or more battery modules in parallel via the battery module terminals to enable parallel charging/discharging via individual switches (104), where each battery module comprises at least one battery cell (105), and a slave control unit (106) configured to monitor a battery condition of the battery module and to determine a battery event based on the battery condition, where the master controller is configured to determine the current control signal dependent on the battery event from any of the battery modules so as to cause a reduction or increase of the charging current, and to determine the current control signal dependent on battery module capacities of the one or more battery

Abstract: A method and a system for controlling the charging and discharging of one or more battery packs (8) connected to a power source (7) or an apparatus (9) driven by the battery packs. The battery pack (8) comprises a number of battery cells connected to two or more terminals for establishing an electrical connection with the power source or the apparatus. The electronic system (2) for controlling the charging of the battery pack (8) and the electronic system (6) for controlling the operation of the apparatus (9) are integrated into the battery pack (8). The battery pack (8) comprises a communications interface for communicating with other battery packs (8) and generates a charging and discharging pool, where the most effective battery pack (8) to charge or discharge is charged and discharged first.