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 Summary
Consists of two main sub-assemblies
1.
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-assemblies
2.
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
Generator + Housing
Phone
Bicycle
Connecting
Power Cable
Frame
Attachment
Phone Holder +
Breadboard
USB
Cable
Customer Needs and Results
Quantitative Objectives
#
Description
1
Voltage Output
4.8-5.2 V
3.9-4.4 V
Current Output
>250 mA
110-410 mA
<$15
~$14.50
2
Target Value
Actual Value
3
Material Cost
4
# of Machines Used in Construction
0
0
5
Duration on Rough Road Conditions
Before Misalignment
>1 hour
>1 hour
Result
Achieves minimum value at 9.67 mph.
Achieves target value at speeds >13.5 mph. Begins
charging at 9.67 mph at 110 mA.
Meets target price, but only just.
Only hand/power tools used in construction.
No misalignment after an hour on rough road
conditions or repeat use on smooth conditions.
Qualitative Objectives
#
Description
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
Easy to install, maintain, and use
8
Protects user safety
9
10
Simple to manufacture
Pass/Fail
~
~
Result
While it’s fundamentally easy to install, proper installation
takes several fine adjustments, instruction, and trial and
error to do correctly
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.
CAD drawings have a high tolerance, process is very simple
Testing
Test
Electrical Testing
Charge All Phones
Engineering Spec
Tested Spec
Test
Pass/Fail
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
>750 mA
250mA< current < 800mA
Bike Charge Test
Pass
Current Generated At Various Bicycle Speeds
450
400
at
Mechanical Testing
Rough Road Test
None
Rough Road
Rough Road Test
Pass
Current (mA)
350
Current
output
average biking speed
300
250
200
150
Environmental Testing
100
Water Test
Resists Water
IEC 60529
IP water test:
spraying water
Dust Test
Resists Dust
IEC 60529
Impact Test Generator
Does not break
dropped/bike crash
IEC 60529
when
Does not break
dropped/bike crash
IEC 60529
when
Impact
Housing
Test
Phone
Level 3
Water Test
Pass
IP dust test: Level 5 dust
protected
Dust Test
Pass
IP impact test: Level 5
(500 grams dropped from
40 cm)
Actual test was 1 meter
drop height
Drop Test
Pass
IP impact test: Level 5
(500 grams dropped from
40cm) Actual test was 1
meter drop height
Drop Test
Fail
Measurements
Pass
50
Bike Tire Range
60.6-71.1 cm
26 inch bike wheel (66cm)
Total Cost
< $ 15
<$15
Weight
Less than current
Less than Current
Number of Machine Tools
Less than 0
Less than 0
Pass
Number of People to
Produce
1 person
1 person
Pass
Number
Install
Less than 1
Zero
(Hands
installation)
0
0
Cost to Install
Tools
to
Pass
Weight Test
free
0
2
4
6
8
10
12
14
16
18
Bike Speed (mph)
General Testing
of
0
Fail
Pass
Pass
• 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
20
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?