In recent years, due to the rapid development of the lithium battery industry, many portable products use voltage measurements to estimate the remaining battery power, but the relationship between battery voltage and remaining power will change with the discharge rate, temperature and battery aging. The error rate of this method can reach up to 50%. As the market's demand for longer-lasting products continues to increase, more precise solutions are required when designing, and smart batteries are born. Smart batteries use TI fuel gauge IC to measure the amount of power charged or consumed by the battery, which will be able to provide more accurate battery power estimation within a wide range of application power levels.