The charging cycle process is: high current pulse charging → cut off the charging channel → brief discharge to the battery → stop discharge → turn on the charging channel → high current pulse charging... This principle is used in the electric car charger, during the charging process, the charging channel is not cut off, and the battery is short-circuited with a small resistance.
In short circuit, because the charging path is not cut off, the inductance is connected in the charging path. Generally in 1 second short circuit 3-5 milliseconds (1 second = 1000 milliseconds), because the current in the inductor can not jump, short short circuit time, can protect the power conversion part of the charger.
If the charging current direction is called positive, the discharge is naturally negative, and the electric vehicle industry has the term \"negative pulse charger\