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
[1]
•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 [2].
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:
[1] [Online] Available: http://www.gadgetreview.com/wp-content/uploads/2006/08/explosion_dcrop1.jpg.
[2] “Lithium Batteries.” [Online]. Available: http://ulstandardsinfonet.ul.com/scopes/scopes.asp?fn=1642.html.
Any Questions?