Independent controlled Hot-plug Switches for Parallel Operation of Reused Battery Strings

The series strings of reused battery cells connected in parallel have different available voltage ranges due to the imbalance between the SoC (State of Charge) and SoH (State of Health) of these cells. Therefore, the utilization capacity of this battery system is limited due to overcharge and over discharge protection of any one of all cells. This paper proposes hot-plug switches to solve this problem. Series battery strings are connected in parallel via switches that are self-controlled according to the state of the battery cell. Experiments have shown that the utilization efficiency of the reused battery system is improved. The proposed switches allow batteries to be hot-swapped without inrush current into the DC bus, and a reliable and redundant power storage system can be constructed.