Senior Design II Final Presentation December 1, 2009

Team Members Jonathan Chapman Duties: Recharging Major: Electrical Engineering Quoc Dang Duties: Recharging Major: Computer Engineering Quintin Grice Duties: Power Circuit Major: Electrical Engineering Richard Teeple Duties: Communication, System Monitoring Major: Computer Engineering David Smith Duties: Fault Protection, System Monitoring Major: Computer Engineering

Overview Problem Solution Constraints Technical Practical Design PCBs Enclosure Bill of Materials Testing

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: Total output current monitoring Ambient temperature monitoring Individual cell voltage monitoring CAN-bus communication

Technical Constraints Name Description Battery Technology The technology used to output voltage from the REBATEM must be lithium ion cells. AccuracyVoltage: 0 to 5 volts with an accuracy of ± 0.1 volts Current: 0 to 6 amperes with an accuracy of ± 20 milliamps Temperature: -30 to 200 °F with an accuracy of ± 2 °F Capacity / Cycle Life 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 ProtectionDisconnect the cells from the system when temperature passes 175 °F or when current passes 10 amps. OutputOutput voltage must be within 12 to 16 volts. CommunicationThe battery management system must communicate cell voltages, temperature and current to external devices.

Environmental Green energy Contains no toxic metals Cadmium Lead

Safety Unstable - needs to be monitored Sony battery recalls UL 1642 [1]

PCB - Main

PCB - Charge

PCBs Charge Board PCB Main Board PCB

Enclosure Side View Inside View

Enclosure Front View Back View

Bill of Materials Main Board (X1) PIC24HJ32(1)$7.00 INA219(1)$3.76 ISL9208IRZ(1)$7.51 MCP2551(1)$1.12 Other Discrete Components$20.00 PCB(1)$33.00 Charge Board (x1) MOSFET 2N-CH(1)$1.20 MAX745EAP(1)$11.61 MAX931CPA(1)$2.46 Other Discrete Components$20.00 PCB(1)$33.00 Enclosure (Estimated)$50.00 Total:$190.65

Total Output

Accuracy-Voltage Setup (No Load) VM BMS Tol VM BMS Tol Results

Accuracy-Current Setup (Test Load = 14.9 Ω) BMS- Voltage (V) Shunt (A) Ammeter (A) Tol Results

Accuracy-Temperature Setup (No Load) Monitored (°C)Measured (°C)Absolute Error Results

CAN Communication

Charging Cells

Any Questions?

References: [1] [Online] Available: [2] “Lithium Batteries.” [Online]. Available: