Solar Jackets’ Racer Battery Management System(BMS) Ali Bibonge Daniel Christopher Paul Martin Mark Slade Taverishima Tsegha December 7th, 2011

Battery monitoring system for a solar powered race car BMS Project Overview Battery monitoring system for a solar powered race car Maintain batteries in a “safe to operate” and efficient state For Solar Jackets’ entry into the American/World Solar Challenge Overall BMS cost of $1200

Proposed Design Objectives It monitors: Li-ion cell over/under voltages Li-ion cell over current Battery pack over temperature Electrically isolate the Li-ion cells Transmits or receives acquired data via RS-485 to racer systems

Current Design Functionality It monitors: Li-ion cell over current Battery pack over temperature Electrically isolate the Li-ion cells The RS-485 communication component has been incorporated into the BMS PCB and is ready for programming

BMS System Flow Chart

Prototyping

Prototyping

Testing Something here...

Demonstration of Temperature Sensor

Demonstration of Current Sensor

System Development Problems Programming of the LTC chip for measuring voltages The LTC chip has been included on the PCB for further programming Georgia Tech milling machine is broken

Total amount spent is approximately $400 Final Budget Total amount spent is approximately $400 This covers the electromechanical relay, LM 35 temperature sensors, ACS758 current sensors, DC fuse/fuse holder, and copper bus/connectors

Battery Module and Cell Thresholds Green Zone Yellow Red Temperature < 40 C 40 C - 45 C > 45 C Discharge Current < 40 A 40 A - 60 A > 60 A Charge Current < 16 A 16 A - 18 A > 18 A Voltage (module) 85 V - 103 V 103 V - 105 V > 105 V Voltage (Li-ion cell) 2.6 V - 3.3 V 3.3 V - 3.6 V 2.3 V - 2.6 V > 3.6 V < 2.3 V

Recommended Future Work LTC programming Incorporating the electromechanical relay into the battery box RS-485 programming Mounting PCB components

Questions?