02/06/031 state of the art battery charger team: richard musumhi bo bo oo pascal openshaw chris...
TRANSCRIPT
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
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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,[email protected]
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
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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
Questions?