**Introduction**
Environmental pollution and energy scarcity have driven the need for new energy sources. To use these new energy sources in a more efficient and sustainable way, battery storage systems have become essential. A Battery Management System (BMS) plays a crucial role in ensuring the safe and effective operation of energy storage batteries. It monitors battery voltage, estimates the state of charge, and provides recommendations for battery runtime.
Early BMS systems were built using distributed components with limited functionality. They mainly focused on monitoring the overall voltage and current of the battery pack, but their accuracy was low, and they could only provide basic protection against over-voltage and over-current [1]. These systems were complex, had poor scalability, and were not suitable for large-scale energy storage applications. This paper presents a BMS design for energy storage batteries that uses the LTC6804 as its core, incorporating features such as cell balancing, battery condition monitoring, and fault alarm functions.
**1. Overview of LTC6804 Functionality**
The LTC6804 is the third-generation multi-cell battery monitoring IC from Linear Technology. It can monitor up to 12 series-connected battery cells simultaneously, and it can also handle smaller configurations where the total series voltage is above 11V. Each individual cell can have a maximum voltage of 8V, and the total series voltage can reach up to 75V. The chip offers a high measurement accuracy of 1.5mV, and it can measure all cells in just 290 microseconds.
The LTC6804 supports an isoSPI communication interface, allowing multiple LTC6804 devices to be connected to a control microcontroller via serial communication. Each device can be individually addressed, enabling parallel management of multiple units. With twisted-pair wiring, the communication distance can extend up to 100 meters.
This IC includes an integrated balancing circuit, which allows direct control of external switches to discharge individual cells when needed. It also has five general-purpose digital I/O pins that can be used for sensor inputs or as communication interfaces. In sleep mode, the LTC6804 consumes only 4µA, making it highly power-efficient.
Additionally, the LTC6804 integrates a 16-bit delta-sigma ADC with a programmable third-order noise filter for accurate voltage measurements. It also includes an auxiliary ADC, which can be configured to use general-purpose I/O pins as input channels. Temperature sensing can be achieved by connecting a thermistor to the ADC input, and battery current can be measured by connecting a Hall-effect current sensor to the same port.
**2. Design of LTC6804 Peripheral Circuits**
The peripheral circuits for the LTC6804 include a power supply circuit, an ADC reference circuit, a communication circuit, general-purpose I/O circuit, a watchdog circuit, and a voltage measurement circuit, among others. The hardware architecture is illustrated in Figure 1. The LTC6804 is powered directly from the battery pack, eliminating the need for an independent power supply.
This design ensures reliable and accurate battery monitoring, making it ideal for modern energy storage systems that require precision, scalability, and efficiency.
This design ensures reliable and accurate battery monitoring, making it ideal for modern energy storage systems that require precision, scalability, and efficiency.
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