Senior Design II

Final Presentation

December 1, 2009

Team MembersJonathan 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

OverviewProblemSolutionConstraints

TechnicalPractical

DesignPCBsEnclosureBill of Materials

Testing

ProblemWhen 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)

SolutionA rechargeable battery system that offers the

following:Total output current monitoring Ambient temperature monitoringIndividual cell voltage monitoringCAN-bus communication

Technical ConstraintsName  

Description

Battery Technology

The technology used to output voltage from the REBATEM must be lithium ion cells.

Accuracy Voltage: 0 to 5 volts with an accuracy of ± 0.1 voltsCurrent: 0 to 6 amperes with an accuracy of ± 20 milliampsTemperature: -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 Protection Disconnect the cells from the system when temperature passes 175 °F or when current passes 10 amps.

Output Output voltage must be within 12 to 16 volts.

Communication The 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

PCBsCharge Board PCB Main Board PCB

EnclosureSide ViewInside View

Enclosure

Front View Back View

Bill of MaterialsMain 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-1 3.69

3.69

3.69

3.69

BMS-1

3.69

3.70

3.69

3.71

Tol-1 0.00

0.01

0.00

0.02

VM-2 4.00

4.00

4.00

4.00

BMS-2

4.02

4.02

4.03

4.04

Tol-2 0.02

0.02

0.03

0.04

Results

Accuracy-Current Setup (Test Load = 14.9 Ω)

BMS-Voltage (V)

Shunt (A)

Ammeter (A)

Tol

15.03 0.975 0.96 0.015

15.04 0.975 0.96 0.015

15.04 0.975 0.96 0.015

15.02 0.975 0.96 0.015

15.03 0.975 0.96 0.015

15.04 0.975 0.96 0.015

Results

Accuracy-Temperature Setup (No Load)

Monitored (°C) Measured (°C) Absolute Error

21.28 21.2 0.08

21.32 21.3 0.02

33.25 32.4 0.85

32.31 32.4 0.09

31.93 32.3 0.37

33.63 33.2 0.43

Results

CAN Communication

Charging Cells

3

3.05

3.1

3.15

3.2

3.25

3.3

3.35

3.4

3.45

3.5

0 20 40 60 80 100 120 140 160 180

Time (s)

Vo

ltag

e (V

) Cell 1

Cell 2

Cell 3

Cell 4

Any Questions?

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.