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Knowledge to Shape Your Future Electric / Gas / Water Information collection, analysis and application MekElekItroniks Design Review Battery Charger Project November 19 2004

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Knowledge to Shape Your Future

Electric / Gas / WaterInformation collection, analysis and application

MekElekItroniks Design Review Battery Charger Project

November 19 2004

Electric / Gas / WaterInformation collection, analysis and application

Knowledge to Shape Your Future

Agenda

System Overview

Project Status

Mechanical Design

Electrical Design

Next Steps

Electric / Gas / WaterInformation collection, analysis and application

Knowledge to Shape Your Future

System Overview

Major Components–Plastic Injection Molded Charger Case

–Charger Labels

–Beryllium Copper Spring Electrical Contacts

–Battery Charger PCB

–Gang Connection PCB

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System Overview

Functional Requirements• User interface is the same as MC-06 with

similar front label and instructions • Same basic shape/color/material as MC-06• Vertical battery installation • Docks with MC-06, using same PCB gang

connection and wall power supply • Docks 2 Li-Ion battery packs• Flashing red LED for charge, solid green

charged• Cost similar to MC-06

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Electric / Gas / WaterInformation collection, analysis and application

Project Status

Electric / Gas / WaterInformation collection, analysis and application

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Battery Charger Development

Mechanical Design:– Rapid prototype generation, iteration, and

testing– SLA generated of Final Design Prototype– Spring contact design prototyped – Injection tooling formulation– Beginning Final Design Documentation

Electrical Design:– Schematic Design– EAGLE Layout– Voltage Regulation Prototype– MAX1737 Design, Prototype– Beginning Final Design Documentation

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Project Costing

Injection Molded Charger Case– Using cost estimate from MC-06– Top Plate - $2.97/unit– Bottom Plate - $1.77/unit

Electrical Spring Contacts– One time tool charge of $9,000 - $11,000– $.08 - $.12 per spring– 6 springs/unit yields a cost of about $2.92/unit

Charger PCB / Electrical Components– Cost of $26.86/unit for all electrical components

Total Cost– Materials - $35.66– Assembly - $3.83– Overhead and Profit - $17.73– Total Unit Price - $57.22

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Battery Charger Schedule11/0409/04 01/0512/0510/04 02/05 04/0503/05

Mech Design

Product Testing

PCB Layout

Elect Design

Inj. Tooling

Design Doc.

Design Doc.

Build Tooling

05/05

Manufacturing

20 Prototypes

Piece/Part Design

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MECHANICAL DESIGN REVIEW

Rory Olson

James Franklin

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Design Overview

Highlights–Updated Design

•Battery Alignment Slots

•Electrical Spring Contacts

–Accommodates Ergonomic Battery Pack

–Exterior similar to MC-06

Features–Curved Battery Pocket

–Drain / Mounting Boss

–Beryllium Copper Electrical Contacts

–Contact Alignment using PCB Design

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Design Overview

Battery Charger Top Plate–Curved Battery Pocket

•Designed around Battery Pack shape

–Three Contacts Slots

•Contact Alignment Fins

–Prevents Shorts

–Pass Core

•Contact Slots

•No need for Expensive Slide Mechanism

–Drain Boss

•Drain Foreign Materials

•Adds Surface Mounting Option

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Design Overview

Battery Charger Bottom Plate

–Similar to Previous Design

–Removed Interior Support Flanges

–Drain Boss Holes

•Moved small Label on Bottom

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Design Overview

Printed Circuit Board–Single Layer PCB

–Sandwiched between Top and Bottom Plates

–Beryllium Copper Spring Contacts

•Mounted underneath of PCB with PEM Nuts and Mounting Screws

–PCB Alignment Slots

•Spacing

•Prevents Shorts

–Battery Pocket Cut-outs

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Design Overview

Beryllium Copper Electrical Spring Contacts

–Beryllium Copper chosen for its formability, high electrical conductivity, high fatigue strength, and corrosion resistance

–Used deflection model to ensure 1/2 lb contact load per contact

–Optimized design using infinite fatigue life model

–Slope face to accommodate sharp battery edge

–Mounted directly to PCB with threaded PEM inserts

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Design Overview

Basic Assembly–Spring contacts mounted to PCB through PEM nuts using screws

–Board captured between case halves

–Two halves screwed together with six mounting screws

–Instruction label place on label surface

–Rubber feet attached to bottom plate using adhesive

–Units connected together using previous gang connection PCB

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Electrical Design Overview

Joe Cote

Lee Solum

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Design Overview

Highlights–Design new charging circuit

•Accommodate one cell Li+ battery pack

•Incorporate original gang connectors

•Maintain original display characteristics

–Meet FCC class A requirements

–Conform to PCB real-estate

Features–Safely and accurately charge battery

–Maintain interconnectivity with MC-06

–Maximize efficiency while minimizing cost

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Design Overview

Charging IC Selection–Logic vs. Microcontroller

•Pros and cons

–Designed for Li+ batteries

•Accurate charging capabilities

•Integrated safety features

–Incorporated Charge Status

•Voltage detection

•Current detection

–Maintain Charge

•Reverse leakage protection

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Design Overview

Voltage Regulation and Protection

–Input Voltage

•Maintain constant voltage

–Noise Prevention

•DC plug protection

•Emissions

–ESD

•Incorporated protection

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Design Overview

Alternate Design–MAX1737

•Incorporated Design

•Expandability

–Pros

•Size

•Component count

•Greater protection

–Cons

•Cost

•Cost

•Cost

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Design Overview

Layout–Software

•EAGLE

–Component Placement

–Routing

–Footprints

•OrCad

–Itron compatibility

–Conflicts

•Importing

•Cross Compatibility

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Next Steps

Mechanical Design:– Design Documentation / Fabrication Drawings– Formulate Plastic Injection Molding Tooling– Build Plastic Injection Tooling– Create Mechanical Prototypes– Assemble Prototypes– Product Testing

Electrical Design:– Design Documentation / Schematics– Create Electrical Prototypes– Product Testing

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Q & A

QUESTIONS