SERIES-PARALLEL BATTERY SYSTEM

A series-parallel battery system includes: a switch (), a series-parallel battery () and a charge and discharge management circuit (). The series-parallel battery () includes a battery combination management circuit () and at least two batteries connected to each other. The battery combination management circuit () is connected to the batteries. One battery in the series-parallel battery () includes a second battery cell () and a third protection circuit (). Other batteries in the series-parallel battery () include a first battery cell (), a first protection circuit () and a second protection circuit (). The switch () is connected to the batteries. The charge and discharge management circuit () is connected to the battery combination management circuit () and used for controlling states of the switch (), of the first protection circuit (), and of the second protection circuit (), so as to adjust a connection mode of the batteries.