Transcript Rechargeable Battery System (REBATEM)
Final Presentation April 13, 2009 Team Members Chapman, Jonathan Dang, Quoc Duties: Recharging Duties: Cell Monitoring Major: Electrical Engineering Major: Computer Engineering Grice, Quintin Smith, David Teeple, Richard Duties: Power Circuit Duties: Fault Protection Duties: Communication Major: Electrical Engineering Major: Computer Engineering Major: Computer Engineering Project Origin This project stemmed from the curiosity of Dr. Marshall Molen and the EcoCar competition. Eight lithium ion cells CAN-bus (Control Area Network) Overview: Problem Solution Constraints Technical Practical Hardware Test Software Test Problem When dealing with lithium ion battery systems, the following aspects must be taken into consideration: Safety Fire and Explosion Communication CAN-bus System Life Weakest Link (individual cell) Solution A rechargeable battery system that offers the following: selective charging over-all current monitoring individual cell temperature and voltage monitoring CAN-bus communication Technical Constraints: Name Battery Technology Description The technology used to output voltage from the REBATEM must be lithium ion cells. Accuracy Voltage: 0 to 5 volts with a tolerance of ± 0.1 volts Current: 0 to 80 amperes with a tolerance of ± 10 milliamps Temperature: -30 to 200 degrees Fahrenheit with a tolerance of ± 2 degrees Cycle Life / Capacity The REBATEM must maintain at least an 80% state of charge for the individual cells and a minimum of a 400-cycle life. Technical Constraints (cont.): Name Description Fault Protection Disconnect the cells from the system when temperature passes 175 degrees Fahrenheit or when current passes 80 amperes. Charge cells up to 80% capacity. Output The output voltage must be within 14 to 16 volts. Current hour rating must be between 3.4 and 3.8 amp hours. Communication The battery management system must communicate cell voltages, temperatures and current to external devices. Environmental •Green energy •Contains no toxic metals • Cadmium • Lead •No toxic fumes released if improperly disposed (incineration) Safety •Unstable - needs to be monitored  •Sony battery recalls •UL 1642 states that users must be protected from risk of explosion or fire due to any instability of the Li-ion cells . Top Level Diagram Hardware Tests Current Sensing Voltage Sensing Temperature Sensing Charging Current Sensing Voltage Sensing Temperature Sensing Charging Charge State Charging Results Before Discharge After Discharge After Recharge Charging Results Continue Software Test Fault Protection CAN-bus Communication References:  [Online] Available: http://www.gadgetreview.com/wp-content/uploads/2006/08/explosion_dcrop1.jpg.  “Lithium Batteries.” [Online]. Available: http://ulstandardsinfonet.ul.com/scopes/scopes.asp?fn=1642.html. Any Questions?