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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 Chris Battaglia (ME) AjeeteshGovrineni (EE) KellenWarriner (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 • 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
First Generation Design • Comprised of two major subassemblies: • Generator Assembly • Phone Container Assembly • DC motor ran along wheel of the bike • Transfer of rotation • Connected to frame via clamp • Phone Housing/Breadboard • Clear tupperware container • Breadboard bolted to container/plastic shield • Contains USB port for phone interfacing • Problems With Design • Expensive (~$20) • Difficult to manufacture on-site (requires milling, lathe) • Not aesthetically pleasing • Poorly optimized from an overall manufacturing/design standpoint
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
Concept Selection • Overhaul or Optimize? • AC vs. DC Motor • If DC, can we find a better motor? • How to incorporate Blackberry phones • Purchase phone holder or manufacture?
Concept Selection Decisions • Ultimately decided to optimize the current design rather than redesign from scratch • MIT product has a similar design, as does several other models on the market (lends credibility) • AC motors not feasible under the scope of the project • Will add Blackberry support via a modular design • Can add a second generator for increased output • Segregates cost between Nokia and Blackberry models • Will design a phone holder, but will reject the design if it’s more than $5 to manufacture.
Drawbacks of A.C Motor • Cost • A.C motor costs more than the whole design for a D.C motor • Manufacture and Repair possibilities • Complex to repair if it breaks down and difficult to manufacture • New design • Will not be readily available for purchase and would depend on manufacture's capabilities
Drawbacks of Solar and Wind Energy • Cost • Will cost more than the D.C motor design and necessary components may be difficult to procure at low costs • Power Source efficiency • The Energy source may not be able to provide enough current to supports various phone models • Durability • May not be able to durable to withstand rough road conditions and rain and mud may cause a breakdown in equipment functionality
Physical Architecture • Modular design on generator housing • Can attach two generators for Blackberry model • Phone container must be near handlebars to provide necessary user feedback • Breadboard in poor location • Generator would preferably run off front wheel to minimize wire losses • Generator housing adjustable along frame rod to accommodate different wheel sizes
Feasibility - Generator • Specs for the generator • $4.62 for 1 and $3.64 for 100 units • Current: 792 mA • Voltage:12 V • RPM: 12850 • Even with conservative estimates we can reach the RPM for rated power • Toque resistance of the motor should be negligible • Must add normal force between the generator rod cylinder and the bike wheel to ensure negligible slip
Going Forward • How can we best optimize the generator housing? • Cost analysis • Breadboard vs. PCB • Can we design a phone holder for under $5?