The invention discloses a cell management system used in an electricity changing energy storage system. The system is used for managing each battery pack in a cell module and each energy storage cell in each battery pack. The energy storage cells in each battery pack are connected in series through a circuit breaker. Each battery pack is connected to a photovoltaic power generation system and a charging pile. The system comprises a main controller, Hall current sensors, relays and Hall voltage sensors, wherein the number of the Hall current sensors and the number of the relays are the same with the number of the battery packs; and number of the Hall voltage sensors is the same with the number of the energy storage cells. The Hall current sensors and the relays are located on the circuit breaker of each battery pack in a one-to-one correspondence mode. The Hall voltage sensors are located on each energy storage cell of the cell module in the one-to-one correspondence mode. The main controller is divided into a main control plate and slave control plates which are connected to the main control plate, wherein the number of the slave control plates is the same with the number of the battery packs. Each slave control plate is correspondingly connected to the circuit breaker on one battery pack, the Hall current sensors, the Hall voltage sensors and the relays.