This is the hardware design section of the BMS project. It was designed with KiCAD.
Here you will find the design, gerber, BOM and render files of the PCB.
As the main goal of this project, this board is designed to support a li-ion battery pack with a 6 series - 3 parallel architecture based on 18650PF cells following the next goals:
- Protection
- Balancing
- Charging/Discharging
- Temperature measurement
- Battery SoC (State of Charge) estimation
To meet the project's requirements we have chosen the following components with their respective role:
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BQ76PL536A: This is a 3 to 6 series lithium-ion battery monitor and secondary protection. It is used as a frontend analog device to measure each series cell voltage and it has dedicated outputs to balance passively through resistors the desired cell.
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INA226: Bi-Directional current and power monitor with I2C compatible interface, we are using this to measure the discharge current, fusioning this data with the voltage measurement of each cell we can infere the SoC of each cell.
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BQ24618: 6 cells Li-Ion battery charger, designed to charge the battery pack at a 4A rate with led status indication.
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STM32F407VGTx: ARM Cortex-M microcontroller with DSP instructions and FPU unit, used to estimate the SoC and control all the peripherals and sensors through their respectives communication protocols applying all the mentioned features earlier. It is enabled to interact with other external devices (such as an on-board computer) through CAN and RS232.
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SN65HVD233: 3.3V CAN Bus transceiver to operate with the latter MCU compatible with ISO 11898 standard. This device is isolated from the rest of the components through the ADuM1201AR.
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IRF9310PbF: Charge and Discarge switch for battery applications, this device is in charge of connection and disconnecting the load from the battery, basically, it's the main endpoint of proetection for the battery pack