The pbm-m series portable battery pack charge / discharge maintenance instrument has the functions of battery module and battery pack charge / discharge, capacity test and voltage balance between modules, and can expand the functions of monomer voltage collection or BMS communication, external online communication and networking work. The series of products adopt high-efficiency power electronic transformation and unique load technology, so that it has a wide range of output voltage adaptation It has the advantages of wide range, complete protection, high reliability, small size and easy portability.