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State of the Art Battery ChargerState of the Art Battery Charger

Team:

Richard Musumhi

Bo Bo Oo

Pascal Openshaw

Chris Privitere

Client:Senior Design

2/6/2003Team

May 03-05

Advisors:Dr. John Lamont

Dr. Richard Patterson

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Presentation OutlinePresentation Outline

Overview– Assumptions, limitations

Activities– Research, design

Time and money– Budget, personnel

Conclusion– Additional work, summary

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DefinitionsDefinitions

PIC– Peripheral Interface Controller

Smart device– Able to make decisions based on inputs

NiCad, NiMH– Most common rechargeable batteries on

the market, Nickel Cadmium and Nickel Metal Hydride

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Project OverviewProject Overview

What is a battery charger?– Takes discharged batteries and restores

their chemical properties using an alternate source of power, such as the sun or a wall outlet.

The need for a new charger– None of the chargers on the market

have as full a feature set as the one that our group has designed.

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Problem Statement - NeedsProblem Statement - Needs

Need a battery charger that is:SmallPortableAmerican, European, or car poweredCharge 1-4 AA/AAA NiCad or NiMH

batteries in 1-2 hours

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Problem Statement - TasksProblem Statement - Tasks

We need to:

1. Convert the power

2. Charge the battery

3. Sense when to stop charging the batteries

4. Control the system

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Problem 1: Power TransformProblem 1: Power Transform

External power– 12V– Commercial 120V and 220V wall adapter– Commercial 12V car adapter

Internal power– DC to DC converter to 6V and 3V– User does not notice

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Problem 2: Charging controlProblem 2: Charging control

Layout

Digital-to-Analog Converter

Peripheral Interface Controller

Current controllers

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Problem 3: Stop charging?Problem 3: Stop charging?

NiCad: A voltage dropNiMH: A temperature riseSafeguards

– Combine both– Max timer– Code checks

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Problem 4: Control the SystemProblem 4: Control the System

Choices– Pre-built microchip– Microprocessor

State machine– The group decided to use a PIC

microcontroller with appropriate code and control.

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The ChargerThe Charger

Working final product: ugly, based on breadboard with plenty of wires

Commercial final product: attractive, cool design, portable.

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Operating EnvironmentOperating Environment

Used indoors or in a vehicleCan not be used in extreme heat,

cold, or wet conditions

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Intended Users and UsesIntended Users and Uses

Designed for the frequent picture taker or other user of electronic equipment

Batteries run out frequentlyCharger will charge the batteries

quickly without damaging them

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AssumptionsAssumptions

Power sources are 120V/220V AC or 12V DC

Charger will charge 1-4 batteriesCharger is only needed indoors or in

a vehicle

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LimitationsLimitations

$100 budgetThe batteries used do not have

“smart” capabilities.The charger cannot draw so much

current that it would kill a car battery.

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End-Product DescriptionEnd-Product Description

Battery charger that can be used on 120V or 220V AC and 12V DC

Can charge 1-4 batteries in 1-2 hoursPortable and easy to use

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Project ActivitiesProject Activities

DefinitionResearchDesignImplementationTestingFinal Product, yay!

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Presentation AccomplishmentsPresentation Accomplishments

Design Spec 80%Components bought 70%Software programming 0%Implementation 0%Testing 0%

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Approach considered and usedApproach considered and used

PLAN AUse a microchip MAX 713Requires no programmingBatteries can only be charged in

seriesMinimum of two batteriesFewer options

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PLAN BPLAN B

Use microchip DS 2770Charges exactly 3 NIMH cells at a timeCapable of charging Lith-Ion batteryTemperature terminatedExpensive

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PLAN CPLAN C

PIC microcontrollerVoltage and temperature sensorsSoftware programming for greater

flexibilityOne battery at a timeMore expensive

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Decisions, decisionsDecisions, decisions

Plan C winsThe PIC microcontroller provided the

most flexibility and options to the team.

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Definition ActivitiesDefinition Activities

Most important requirement– Should be able to operate on 120v

ac/60Hz, 12v DC, 220v ac/50Hz.Charge AA/AAA.Discharge/conditioningTrickle chargePortable

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Design ActivitiesDesign Activities

External transformer– Convert 120/220V to the 12V

Internal transformer– Change 12V to internal levels needed

Circuit– Various digital to analog converters, current

controllers, and sensors Software

– State machine to start and terminate fast battery charging

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Research ActivitiesResearch Activities

Handbook of Batteries,third edition.David Linden and Thomas B.

Reddy,McGraw-Hill,New York 2002

John Oeler,john.oeler@dalsemi.com

For Dallas technical support

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Implementation ActivitiesImplementation Activities

Purchasing– Most components purchased

Circuit board setupSoftware testingSoftware upload

– Final product should function on its own without any glitches

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Testing ActivitiesTesting Activities

Digital to Analog accuracyCurrent control accuracyDetecting voltage and temperature

changes properlyProperly charge 10 batteriesNo overheating

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Testing Activities continuedTesting Activities continued

Detect insertion/removal of a battery causing circuit to be reset.

Final product functionality

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Resources - PersonnelResources - Personnel

361 hrs448 hrsTotal

87 hrs121 hrsChris Privitere

98 hrs128 hrsPascal Openshaw

91 hrs99 hrsBo Bo Oo

85 hrs100 hrsRichard Musumhi

RevisedOriginal

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Resources - FinancialResources - Financial

$73.00$89.00Total

$24.00$24.00Batteries

$44.50$59.00Digital IC’s and adapters

$4.50$6.00Microprocessor

RevisedOriginal

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Risks & Risk ManagementsRisks & Risk Managements

The loss of team member– Document work

Microprocessor might not be useful– Alternatives

Delays in product shipments, damage of parts– Purchase extras and in advance

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Lessons learnedLessons learned

Start earlyCommunication is importantManage time efficientlyGood documentationGet help from faculty advisors

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Additional workAdditional work

Create a generic design that can be commercialized

Optimize the cost for mass production

Increase capabilities

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CommercializationCommercialization

Device cost

- PIC: $4.50 - LEDs: 1.00 - battery monitors:

7.00 - LED driver:

4.00 - transc amps:

1.00

- 12 V wall adapter $10.00

- 12 V car adapter 7.00

- plug receivers 1.00

- DC to DC converter 6.00

- DAC 7.50

TOTAL = 49.00

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Commercialization cont.Commercialization cont.

Estimated total cost, no bulk– $ 49

Distributor price– $ 70

Retail Price– $ 90

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Project SummaryProject Summary

State-of-the-art battery charger – Can be used worldwide– Easy to use– Portable– 1 year of development

02/06/03 1

State of the Art Battery ChargerState of the Art Battery Charger

Team:

Richard Musumhi

Bo Bo Oo

Pascal Openshaw

Chris Privitere

Client:Senior Design

2/6/2003Team

May 03-05

Advisors:Dr. John Lamont

Dr. Richard Patterson

Questions?