HyTech Racing is an award-winning student-run organization at the Georgia Institute of Technology dedicated to furthering students' engineering experience through the rigorous design and development of Formula SAE electric vehicles. Every year, we design, build, and race a brand new student-designed single seater electric formula style racecar. Thanks to JLCPCB for providing us with this sponsored PCB.

HyTech Battery Management System (BMS) Segment

HyTech Racing utilizes a custom battery pack with a nominal voltage of 310V that is split into four battery segments of 21 cells each. Each battery segment is monitored by its own BMS segment, resulting in a semi-distributed battery management system. 

The 21 cells are connected to the BMS segment through the use of spring contacts that are soldered to the pads shown above. This allows the BMS segment to maintain electrical contact with the batteries under the vibrations and shocks the pack experiences while the vehicle is in motion.  

At the heart of the battery management system segment are two LTC6811-2 multicell battery monitors from Analog Devices. This IC can monitor the voltages of up to 12 cells in series, taking voltage readings with total measurement error of less than 1.2mV at a user-selectable data acquisition rate. Each of HyTech's battery segments contains 21 cells, which results in an architecture where one IC monitors 9 cells, while a second monitors 12 cells. Each chip is independently addressable, with the chip addresses set through the use of jumper resistors to represent the address in binary. The IC communicates through isoSPI, a proprietary version of the SPI protocol that uses a twisted pair to achieve isolation and allows us to read data on our control unit. 

Battery temperatures are monitored using thermistors that in contact with metal directly touching the battery leads. Using the GPIO available on the LTC6811, temperature data is transferred to the control unit, allowing HyTech to monitor for safe temperatures. The LTC6811 also internally monitors IC temperature, and the board also contains two dedicated temperature and humidity sensors to monitor for ambient temperature and water ingress inside the battery pack container. 

PCB Fabrication at JLCPCB

The BMS Segment PCB fabrication has been generously sponsored by JLCPCB. Their quick turnaround times and high quality products allow us to prototype our designs more efficiently and effectively. Ordering from JLCPCB is simple: simply hit the Order Now button, upload your gerber zip file, and you're all set! HyTech frequently uses and highly recommends JLCPCB for PCB fabrication needs.