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Bike Cellphone Charger

Bike Cellphone Charger. Chris Battaglia (ME) Ajeetesh Govrineni (EE) Kellen Warriner (IE). Project Summary and Background. Create a system that harvests human waste energy and converts it into electricity in order to charge a cell phone To be used in Haiti

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Bike Cellphone Charger

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  1. Bike Cellphone Charger • Chris Battaglia (ME) • Ajeetesh Govrineni (EE) • Kellen Warriner (IE)

  2. Project Summary and Background • Create a system that harvests human waste energy and converts it into electricity in order to charge a cell phone • To be used in Haiti • Collect energy from riding a bicycle • Previous team designed a system (upper right) but proved expensive, unappealing, difficult to manufacture, etc. • Includes generator and cell phone holder • Current plan is to optimize old design and achieve better results • Using MIT’s design (lower right) as the standard to meet/exceed

  3. Customer Needs • Must be able to charge Nokia cell phones (250mA, 3.5V) • Ability to charge Blackberries (750mA, 5V) desirable but not strictly necessary • Design should be adaptable and fit a variety of bicycle frames • Easy installation (little to no tool use) • User feedback is important, user wants to see the phone charging • Total material costs should be <$15 with <1hr labor • MIT design is $11 but lacks phone housing • Willing to ship materials and more complicated components (breadboard, generator, etc) but main assembly should be done on-sight with minimal supervision • Should not use any machining equipment more complicated/expensive than hand tools • Forgiving tolerances • Design should be simple enough to repair and/or cheap enough to replace if broken

  4. Customer Specifications

  5. Test Plan

  6. Project Risk Assessment

  7. Technical Risk Assessment

  8. Technical Risk Assessment

  9. Same general design but with a few modifications Housing is made of cut stock PVC pipe End caps are glued along the inner diameter of the PVC and are made of cut Plexiglas Opted for simplicity and low cost over complexity and utility (details in next slide) Not shown: Weather stripping around generator for cushioning Small spring acting against generator inside the housing Shaft for generator rod has twice the diameter in clearance Will hopefully be enough to hold generator shaft against any bike wheel. May need adjustments. Generator Housing Design

  10. Generator Housing CAD Drawing

  11. Generator Housing Concept Selection • The need to machine metal (even just drilling) made choices undesirable • Most of the options seemed too flimsy or expensive • Ultimately needed to “step back” and return to the simplest solution for this project • Kept the “wiggle shaft” idea and made it internal

  12. Frame Attachment • Needs to support 4+ times the housing’s weight under rough road conditions (-Prof. Lam) • Lack of machining equipment in Haiti prompts a purchased pre-manufactured component • Generator can be removed by hand later, but only with added cost (clamps, wing nuts, etc – all more expensive) • No sure way to determine which options (See below) would be best. Luckily options are easily interchangeable so we can experiment during testing • Will be used both on the frame and the generator housing • No need to machine into the housing • Shouldn’t need an arm to bridge the two, but one can be made from plastic if necessary $0.10 - $0.50 $0.75 - $1.50 $2.00 - $2.50 $2.50 - $2.75 (Current Design)

  13. Decided to use a breadboard over PCB Cost Heat generation is the biggest concern mechanically Analyzed under very conservative conditions (no convection whatsoever) Nokia (3.75W) setup passes, Blackberry (10W) does not (see right) Current design is to place the breadboard in a separate housing Made of same materials as generator housing Thermal testing may show that it can be safely placed in the generator housing Generator shaft and any metal fasteners may dissipate enough heat Circuit Board Housing Design

  14. Heat Transfer Calculations

  15. Phone Housing Design • Alternative Design to the purchased phone holder • More expensive • More labor intensive • Not necessarily a bad thing • Can be manufactured in Haiti • Made out of cut sheet stock, glue, and one metal dowel

  16. Phone Holder CAD Drawing

  17. Material Selection

  18. Manufacturing • Goal of project was to make device as cheap as possible • Use of mass produced product • PVC pipe • Plexiglass • Steel rod and tubes • Tools Used: • Handsaws, Cordless drill

  19. Manufacturing • User Assembled • Cheaper • Create jobs • Slow assembly time • Learning curve • Incorrect assembly results in device not working • Preassembly • Costs more (labor in U.S.) • Lower risk of assembly mistakes

  20. Circuit Selection

  21. Circuit Simulation

  22. Bill of Materials

  23. Bill of Materials

  24. Moving Forward

  25. Moving Forward • MSD II Project Plan • Address Issues in Detail Design Review • Purchase components with long lead times

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