Bike Cellphone Charger

• Chris Battaglia (ME)• Ajeetesh Govrineni (EE)

• Kellen Warriner (IE)

Project Summary and Background• Second generation project (see right)• Design a bicycle cell phone charger for use

in Haiti and other underdeveloped countries•Includes generator, breadboard, and phone holder

• Total material cost should be <$15 and manufacturable on-site in Haiti•No heavy machinery used (lathe, mill, etc)

• Time needed to charge a phone must be reasonable for the user•Nokia and Blackberry phones. Primarily target is the former

• Design must be simple, robust, easily repaired/replaced, and adjustable

Old Design

Our Design

Design SummaryConsists of two main sub-assemblies1. Generator Housing

• Generator is enclosed in plastic cylindrical housing with shaft extending out

• Shaft is held against the tire of the bike, friction turns the shaft

• Held to bike frame via two rubber-lined clamps joined with a bolt and wing nut

Consists of two main sub-assemblies2. Phone Holder

• Contains breadboard and power connector

• Comfortably holds Nokia and Blackberry phones and adjoining cables

• Attached to handlebar of bike with two Velcro strips

Product Performance & Information• Half-charged a Nokia phone in 25 minutes

• Takes approximately 6-8 hours of continuous use to deplete the battery

• Requires 1-4 hours (based on speed) to fully charge a phone• Approximately 1:2 Work to Use Ratio on average

CONTAINED IN KIT

BicycleFrame

AttachmentConnecting

Power Cable

Phone Holder + Breadboard

Generator + Housing

Phone

USB Cable

Customer Needs and Results# Description Target Value Actual Value Result

1 Voltage Output 4.8-5.2 V 3.9-4.4 V Achieves minimum value at 9.67 mph.

2 Current Output >250 mA 110-410 mA Achieves target value at speeds >13.5 mph. Begins charging at 9.67 mph at 110 mA.

3 Material Cost <$15 ~$14.50 Meets target price, but only just.

4 # of Machines Used in Construction 0 0 Only hand/power tools used in construction.

5 Duration on Rough Road Conditions Before Misalignment >1 hour >1 hour No misalignment after an hour on rough road

conditions or repeat use on smooth conditions.

Quantitative Objectives

# Description Pass/Fail Result

6 Charger fits standard phone connectors Fits any standard USB cable (typically shipped with phone)

7 Aesthetically pleasing; provides user feedback Reactions to the design have been positive

8Easy to install, maintain, and use While it’s fundamentally easy to install, proper installation

takes several fine adjustments, instruction, and trial and error to do correctly

9Protects user safety While a potentially minor issue, the breadboard is

uncovered and may present a hazard. The generator shaft also becomes painfully hot to the touch after use.

10 Simple to manufacture CAD drawings have a high tolerance, process is very simple

Qualitative Objectives

~~

TestingTest Engineering Spec Tested Spec Test Pass/FailElectrical Testing Charge All Phones

Universal Connection Tested with USB Bike Charge Test Pass

Output voltage

4.7 V -5.3 V 4.8 V - 5 V Bike Charge Test Pass

Max Current

>750 mA >730 mA Bike Charge Test Pass

Current output at average biking speed

>750 mA 250mA< current < 800mA Bike Charge Test Pass

Mechanical Testing Rough Road Test

None Rough Road Rough Road Test Pass

Environmental Testing

Water Test Resists WaterIEC 60529

IP water test: Level 3 spraying water

Water Test

Pass

Dust Test Resists DustIEC 60529

IP dust test: Level 5 dust protected

Dust Test Pass

Impact Test Generator Does not break when dropped/bike crashIEC 60529

IP impact test: Level 5 (500 grams dropped from 40 cm)Actual test was 1 meter drop height

Drop Test Pass

Impact Test Phone Housing

Does not break when dropped/bike crashIEC 60529

IP impact test: Level 5 (500 grams dropped from 40cm) Actual test was 1 meter drop height

Drop Test Fail

General Testing

Bike Tire Range 60.6-71.1 cm 26 inch bike wheel (66cm) Measurements Pass

Total Cost

< $ 15 <$15 Pass

Weight

Less than current Less than Current Weight Test Fail

Number of Machine Tools Less than 0 Less than 0 Pass

Number of People to Produce

1 person 1 person Pass

Number of Tools to Install Less than 1 Zero (Hands free installation)

Pass

Cost to Install 0 0 Pass

Current Generated At Various Bicycle Speeds

0

50

100

150

200

250

300

350

400

450

0 2 4 6 8 10 12 14 16 18 20

Bike Speed (mph)

Cu

rren

t (m

A)

• Current/Voltage test• Output at various speeds• See above graph

• Rough road test• Road bike on rough terrain,

checked generator positioning

• Impact test• Drop test

• Environmental Damage test• Water and dust test

Suggestions for Future Work

• Better means of holding the nub of the generator shaft against the tire•Optimize potential output•Simplify installation

• Cheaper components / overall cost reduction•Certain items are large contributors to the overall cost

• Powerjack Cable, etc• Better generator? Remove breadboard?