MAINTAINING CELL STATE OF CHARGE BALANCE IN LITHIUM ION BATTERIES

摘要

Because they have no safe overcharge mechanism, most lithium ion batteries require some sort of external means for compensating differences in self discharge rates between series-connected cell blocks. (A cell block consists of one or more cells connected in parallel). Without this, the useful capacity of a battery would diminish steadily with time. This paper describes some simple and potentially low cost solutions for maintaining state of charge balance. Tests with real batteries and breadboard circuits have amply confirmed the correct operation of the concept. A preferred solution suitable for batteries with cell failure tolerance has been analysed in detail.