A battery management system includes an external non-volatile memory and a battery management chip with embedded SRAM, CPU, ROM, and ROM_RAM encoder. The chip communicates with the non-volatile memory via standard protocols. While the battery management system is powered on or reset, a battery management program stored in the non-volatile memory is loaded to the embedded SRAM and the executed by CPU. As turning off this system, the program in the SRAM is then restored back the non-volatile memory. A battery protection IC is optionally embedded in the chip or externally connected with this chip to protect the battery from over-/under-voltage, over-current and short-circuit in both charge and discharge.