Accharge: Portable Cell-Phone Charger Final Report Aaron Levine, Eric Li, Jithu Jose, Vaisakh Mani Executive Summary Accharge is a business focused on bridging the gap between India‟s overdrawn electrical infrastructure and the energy demands required by India‟s rapidly growing population of cell -phone users. Accharge is a portable mobile-phone charger that provides a reliable supply of electricity to commuting professionals in Kerala. The basic model of the charger includes a wind-turbine that can provide these users with a significant electricity supply while in transit. Furthermore, the device has connection ports for a variety of add-ons that the individual customers can opt to purchase so as to instill the device with the versatility that their day to day activities demand. The Accharge will allow for mobile-phones, an increasingly ubiquitous necessity, to be a more reliable means of communication in regions with an inconsistent electric supply. Our product philosophy is summarized in the company name: Accharge. A combination of the Hindi word „Accha‟ - meaning „good‟ - with the English word „charge‟ - the primary function of our product - the name carries the connotation of a device that can provide a reliable and significant supply of power to users‟ phones. Furthermore, the name can be interpreted as AC-Charge, giving users the impression of the ease of use and accessibility associated with AC outlets. Through extensive research which served to inform a number of product revisions, we gained deep insight into the cell-phone market in Kerala and how the mobile phone has transformed day to day life there. We developed a business plan that intends to provide these individuals with a cheap yet robust solution to their energy needs and allows for the product to be customized and tailored to their individual requirements. Though a full scale prototype was not completed, we made significant inroads into examining the feasibility of this product, along the way learning a great deal about Indian culture and the process of developing a product from concept to company. Cultural Understanding To glean insight into how individuals in Kerala would perceive our product and, more broadly, how our product might fit into the culture of Kerala as whole, we collected data that focused on prospective users through personal interviews as well as more general information from Internet sources. An interview of twenty people living in Kerala provided valuable information to guide the efforts and focus
22
Embed
Accharge: Portable Cell-Phone Charger Final Reportpickar.caltech.edu/me105/papers/Team5-Accharge_FinalReport.pdfAccharge: Portable Cell-Phone Charger Final Report Aaron Levine, Eric
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Accharge: Portable Cell-Phone Charger Final Report
Aaron Levine, Eric Li, Jithu Jose, Vaisakh Mani
Executive Summary
Accharge is a business focused on bridging the gap between India‟s overdrawn electrical infrastructure
and the energy demands required by India‟s rapidly growing population of cell-phone users. Accharge
is a portable mobile-phone charger that provides a reliable supply of electricity to commuting
professionals in Kerala. The basic model of the charger includes a wind-turbine that can provide these
users with a significant electricity supply while in transit. Furthermore, the device has connection ports
for a variety of add-ons that the individual customers can opt to purchase so as to instill the device with
the versatility that their day to day activities demand. The Accharge will allow for mobile-phones, an
increasingly ubiquitous necessity, to be a more reliable means of communication in regions with an
inconsistent electric supply. Our product philosophy is summarized in the company name: Accharge.
A combination of the Hindi word „Accha‟ - meaning „good‟ - with the English word „charge‟ - the
primary function of our product - the name carries the connotation of a device that can provide a
reliable and significant supply of power to users‟ phones. Furthermore, the name can be interpreted as
AC-Charge, giving users the impression of the ease of use and accessibility associated with AC outlets.
Through extensive research which served to inform a number of product revisions, we gained deep
insight into the cell-phone market in Kerala and how the mobile phone has transformed day to day life
there. We developed a business plan that intends to provide these individuals with a cheap yet robust
solution to their energy needs and allows for the product to be customized and tailored to their
individual requirements. Though a full scale prototype was not completed, we made significant inroads
into examining the feasibility of this product, along the way learning a great deal about Indian culture
and the process of developing a product from concept to company.
Cultural Understanding
To glean insight into how individuals in Kerala would perceive our product and, more broadly, how our
product might fit into the culture of Kerala as whole, we collected data that focused on prospective
users through personal interviews as well as more general information from Internet sources. An
interview of twenty people living in Kerala provided valuable information to guide the efforts and focus
of our product, while the online research we conducted served to further corroborate and embellish
these findings.
All interviewees reported that they had access to electricity but that there were significant issues with
the reliability of the electric supply. In other words, finding an outlet proves unanimously easy, but that
the outlet actually supplies the requisite electricity is not guaranteed and is frequently not the case.
Furthermore, despite India‟s identity as a developing country, and the frequently fallacious assumption
of an undeveloped technological infrastructure that accompanies this label, it is actually the second
largest cell-phone market in the world with a staggering 671 million mobile phone users, over twice the
total population of the United States.1 This ubiquity is reflected by the individuals we interviewed, who
themselves all own cell phones, and reported that cell phone use is now a deeply ingrained aspect of
daily life in Kerala. These interviewees further expressed that they had to frequently contend with
insufficient battery life for their cell-phones as a result of the unreliability of the electric supply. A
telling indication of the importance of cell-phones in the culture of Kerala is that the individuals we
interviewed told us that making a call in an emergency situation was of extreme importance.
As a society, India has readily and rapidly embraced the use of cell phones. India is in fact the largest
growing cell-phone market in the world and undergone unparalleled growth over the past decade. In
2002 there were only 6.4 million users, a vanishingly small number when compared to the current
number and when 20.31 million new mobile phone customers were added in March 2010 alone.1
Furthermore, this market shows no signs of slowing and is expected to reach 1 billion users in 2012, at
which point India is projected to be the largest cell-phone market in the world with 84% of its
population owning a cell phone.1
Cell Phone Usage from 1995 to 2008
Cell Phones (in Millions)
In contrast, the wired infrastructures in India, such as landlines and electricity supply, lag far behind the
growth of cell-phones. India is widely known to have a poor quality of power supply and frequent
power cuts and shortages, and “it is common for the 44% of rural households having access to
electricity to lose power for more than 12 hours each day”.2 This electricity shortage arises from the
disparity between the rapidly growing population and the current power generation capabilities. Kerala
has a maximum energy production capacity of 2657.24 MW while energy demands there have
exceeded 2800 MW, leading to rolling blackouts.3 This problem is not constrained to the state level and
in India as a whole, energy shortage reached 14.6% in April 2010.4 This information, along with the
reports of blackouts from our interviewees, helps to illustrate the unreliability of electricity in India.
Another important aspect in informing the power generating functionalities of our charger is the
prevalence of public transportation and the frequency with which it is used in Kerala. 90% of the
interviewees reported that they used public transportation with total travel times typically between 1
and 2 hours in a day. Furthermore, the most common forms of public transportation either don‟t have
electrical outlets, in the case of buses, or have very few, and consequently heavily congested outlets,
such as on trains. In summary, the increased reliance on cell-phones for communication coupled with
the over-strained and unreliable electricity supply in India suggest a large market for those who use
cell-phones and would like the assurance that their cell-phone could be charged and used at any time.
Both cell-phone usage and electricity demand in India are rapidly increasing and, accordingly, there is
growth in the market for a portable cell-phone charger.
Market Definition
Target Market.
Primary Market: Commuting professionals in Kerala who lack reliable access to electricity and rely
on mobile-phones for business and personal purposes
Secondary Market: Frequent users of public transportation who do not have reliable access to an
electric supply, such as students, and mobile phone users who desire to have a backup plan in
emergency situations
Markets Explained.
Many white-collar workers and small business owners live in rural villages and commute to the larger
cities where their places of work are located. This demographic includes vendors of various goods,
those employed in the private sector, and government doctors and teachers. These individuals tend to
be well educated and receive relatively high salaries. They rely heavily on their cell phones for
communication of both a business and personal nature but lack consistent access to a reliable power
source. Therefore, a mobile charger outfitted with the basic functionality of a wind turbine would be
ideal for charging their phones during the one to two hours of these individuals‟ average daily commute
time. Moreover, the various other methods of charge generation (hand-crank, hand-pump, and battery
functionality) that may be optionally added onto the basic charger will provide users with a versatile
device can be tailored to their specific needs.
Additionally, from our research, we know that many students rely heavily on their cell phones and
frequently use public transportation, often commuting for upwards of one to two hours each day. These
characteristics make them obvious beneficiaries of a mobile cell-phone charger.
DFX
Design for Extremely Low Cost.
By using locally imported goods, we reduce the overhead costs of transporting materials long distances,
as well as avoiding potential taxes and customs by going through international or state lines. In this
manner, using locally imported goods will reduce costs. An added benefit is that the closer our supply
of materials is, the faster we can get materials to produce our product, which could have a significant
impact on our speed of production.
Wisely choosing to import or produce parts could also lead to significant cuts in cost. For instance, take
the example of the battery-powered input portion of our device. We know that in manufacturing it we
will need the machines by which it is made, labor, and cost of materials, among other things, which will
likely equate to heavy costs. In doing further research, we may find that especially during the fledgling
stages of the product, it may be worth it to avoid the fixed costs (such as purchasing the machines) and
to purchase the battery-powered input from a third party supplier that is either pre-made or can be easily
assembled by manually putting pieces together. In this way, we might save much capital initially by
purchasing it from a supplier, and then further on switching over to self-producing when the fixed costs
are small relative to our revenue generated.
If we ensure that our product does not have any extraneous, unnecessary features that may constrain the
design and make it much harder to manufacture, we will be able to reduce our costs significantly. By
making a simple device that is uncluttered, it will be easier to manufacture as well as requiring less time
and materials, which will all lead to lower costs in the long run.
Moreover, making tolerances too small, while trivial from an engineering standpoint, can cause a
myriad of problems at the factory level. It may be the case that the machines and the workers are not
equipped to manufacture with very small tolerances. In trying to meet the tolerances specified by the
engineers, they may waste a lot of valuable time, energy, and resources for something that ultimately is
insignificant. So by making sure that we avoid unnecessarily wasting resources, we will be able to
significantly cut costs.
What materials we choose to use will also have a large impact on the overall cost of production. We
will avoid using expensive materials that add unnecessary improvements to our product. For example,
the casing of our cell-phone must be durable in order to withstand the stresses of use. To make our
product extremely durable, we could choose to use a steel casing. However, as we have seen from most
commercial cell-phone chargers, plastic will likely do a more than satisfactory job. By making
decisions such as these, we can also cut costs.
Design for Environmental Friendliness.
To be environmentally friendly, we will use eco-friendly materials that will ensure that our product will
not harm the environment at any stage during its lifetime. The three critical stages we have targeted are
the production and manufacturing of the charger, the use of the charger, and the disposal of the charger.
During the manufacture of our charger, we will ensure that our factories are not releasing harmful
pollutants into the atmosphere. We will be able to accomplish this by avoiding the use of hazardous
ozone-depleting substances, as well as implementing systems which will strictly monitor the chemical
output of our factories. Moreover, we will not allow any of our factories to dispose of waste by
dumping impure wastewater into lakes, oceans, streams, and other bodies of water. Again, a monitoring
system will be in place to thoroughly regulate the purity of wastewater that may be flowing to natural
sources of water to make certain that we are not inadvertently contaminating water supplies.
As for the use of our product, we have designed our product so that it does not emit or give off harmful
radiations or toxins that could harm both the user and the environment. Additionally, this product is
inherently environmentally friendly since it is an alternative to methods of electricity generation that
make use of fossil fuels. Hence, use of our product will decrease the demand for these harmful
electricity generation methods, which will benefit the environment in the long term.
The various components of the cell-phone charger will be composed of disposable and recyclable
materials whenever possible. Our factories and vendors will accept unwanted or worn out chargers that
we will personally process ourselves. In fact, we hope to reuse any salvageable components of our
device, such as the snap-on plastic casing. For any unrecyclable materials, we will make sure that they
are properly disposed of in a manner that will not harm the environment.
Design for Safety.
The most dangerous aspect of our product is the wind-turbine. However, for maximum portability the
wind-turbine is designed so that it is collapsible and therefore will be made of plastic, greatly
minimizing the chances that the blades will injure someone. Furthermore, to protect the blade and
prevent the user from coming in contact with the spinning blade, a plastic casing will encircle the
turbine. In this manner, the wind turbine will be very similar in nature to box fans, which countless
people around the world know to be safe from extensive use.
Another potential danger arises when affixing the charger to a window for wind-powered charging.
Because the charger is affixed on the inside of the conveyance, it could fall onto the user if not
strongly held in place. Therefore the charger must be able to withstand the considerable force of
oncoming wind. We will use stronger-grade Velcro straps that have been demonstrated to withstand
very strong forces (175 lb force for a 2 in2 piece) that will wrap securely around the bars which serve
as windows in the majority of buses and trains in India (Please see picture below).5 To be certain that
Velcro straps will reliably affix the charger, we will rigorously test the Velcro straps to eliminate this
danger and ensure consumer confidence. It is noteworthy that the charger is affixed to the inside of the
means of transport, which is considerably safer than if it were affixed to the outside where it could be
hit by or fall onto oncoming traffic and pedestrians.
Common Indian Bus
Beyond these two considerations, the device poses no other real dangers when used properly. Neither
the battery nor hand pump is amenable to misuse in a way that could result in any kind of injury.
While it is possible for repetitive motor injury to occur if physical methods such as the hand-pump or
hand-crank are used excessively, we envision that these methods will be primarily used in emergency
situations where only a phone call or two is necessary to ameliorate the situation, after which the
charging may be performed at a more relaxed rate.
Design for Maximization of Power Output.
We will employ various methods to extract maximum power while maintaining a compact design. One
such method will be to use a foldable fan that expands to a radius of approximately 2.5 inches when in
use. From the wind power equation, we know that power generated by the turbine varies with the
square of the radius of the rotor. Thus, in using a fan that expands to a larger radius than if it were
directly attached, we are able to generate significantly more power. We will also use a gear box for all
methods which generate charge through rotation. This will allow us to minimize the physical strain on
users, while maximizing the power output that comes from their inputted force. In addition, our design
is such that the majority of power supplied by our charger will be sent to the mobile-phone. By using a
simple indicator light system which requires minimal electricity to power it, we will avoid using
precious electricity for unnecessary features, with most of our electricity going to the primary
functionality of our charger.
Design for Human Interface.
Our goal in the design of the interface of the Accharge was to make it simple and intuitive. To this end,
there will be no “modes” or unnecessary features in our product that could confuse the consumer, one
simply uses the product. Each face of the device will be devoted to a single functionality so no
confusion arises when attempting to use a particular feature, and by isolating each component the
operation and purpose of that component will be made more apparent. Furthermore, this will ensure the
product is uncluttered. The basic model comes with the collapsible wind-turbine on the front and an
attachment port for a mechanically powered add-on on the opposite face. On the top and on one side of
the device will be connection ports for add-ons that directly produce electricity. Lastly, the cord that
transfers the generated charge to one‟s cell-phone will extend from the bottom.
It is important for the user to be able to know how much power is stored in the charger and how much
power is being output. This will be achieved through two clearly labeled indicators, which are
unobstructed and prominently located on the remaining side of the device. For the sake of simplicity
and ease of understanding, both indicators will consist of 4 LEDs that indicate full power when all are
lit and no power when none are lit.
Furthering our aim of intuitive use, all functionalities will be simple enough that one can deduce the
intended use by observation. For example, the battery add-on will be a cylindrically shaped slot that
only the battery could fit into. The user will quickly discover that when the wind-turbine turns, or the
hand pumped is pressed down that power is generated as shown by the indicator lights. Additionally, a
small manual that accompanies the product will outline the use of each component through clear figures
and concise instructions.
Design for Assembly.
In the interest of increasing the production rate of our product and minimizing the requisite amount of
worker expertise, it is advantageous to make the product as intuitive to assemble as it is to operate.
This will be achieved by making the various pieces of the product snap together in the casing. On the
inside of the case will be a space for the dynamo and shaft to snap in and a region for the circuit board
to snap in. Furthermore, the wind turbine can snap directly onto the shaft through a common component
that will allow for any of the mechanical add-ons to be substituted in for or used in accompaniment with
the turbine. This also minimizes the amount of screws necessary in the construction of the product and
avoids many of the common bottlenecks of production (such as screwing or soldering pieces together)
by having most of the attachment mechanisms be included in the case‟s molding. Also, by making the
add-on components separately and having the user attach these at their discretion, they are essentially
aiding in the assembly process.
Design for Maintainability and Reliability.
Since the Accharge is somewhat expensive we want it to last a long time, a goal made more achievable
if maintenance of the device is easy for the user. Every charge-producing component of the device is
interchangeable. Therefore if any break, it is a simple task to disconnect the damaged component and
use a working one in its place. For the more complex modes of energy production, replacement pieces
will be available so that the whole component doesn‟t have to be removed when only a small amount of
damage has been incurred. For example, the blades of the turbine, which undergo the most stress, can
be swapped out for new blades. By making the external functionalities of the device replaceable, the
durability of the product will increase.
Because of the snap-together assembly of the case, the device is easily opened to give the user access to
the dynamo and the output cord so that these too can be replaced in the case of damage. Because the
Accharge is essentially a group of distinct energy-generating functionalities brought together on a
single frame, each component operates independently of the others so that the failure of any one
component does not compromise the proper functioning of the device as a whole. This graceful failure
model is central to the reliability of the device since it virtually guarantees that the majority of the
energy-generating components will be functional at any given time.
A final consideration is the materials used for the product, which largely determine how it withstands
operational stress and, consequently, how long the device will last. Although cost is important, the
materials used, particularly the casing, will be strong enough to endure the forces it will be subject to
through constant use. In addition, areas subject to rotational stress, such as the wind-turbine axel and
hand-pump, can be easily lubricated.
Design for Individual Customer Needs.
Because our target market is broad it is important that the device can be easily adapted to the needs of
each individual. For this reason, the central unit of the charger includes only the wind-turbine
generating component since this is a need common to our market of commuting professionals.
However, a variety of add-ons will be made available for the customer to selectively purchase in order
to provide them with means of power generation that best complement their day-to-day activities.
Components that provide a direct source of electricity (such as the AA charger and outlet adapter) can
be connected through ports located at the top and side of the device that serve to both fasten the
component to the case and provide an electrical connection from the component to the circuit board.
Generating functionalities that rely on mechanical input (such as the hand-crank or pump) connect to
the rotation shaft through a hole in the front and back of the device (initially the product comes with the
turbine connected through the hole in the front). The customizable nature of the Accharge also reduces
the cost to the user since no user has to pay for a component they won‟t use.
The dynamic nature of this design is best illustrated when considering the widely varying conditions
individuals of differing vocations may encounter during the course of their work. For example, a vendor
who constantly finds himself in remote villages with poor electricity access for business would highly
value a hand-pump or hand-crank on his cell-phone charger as a safeguard in emergency situations. At
the same time, a teacher who typically commutes to and from the same locations each day may opt for
the battery functionality that can charge her phone reliably when he or she is in a classroom setting.
Product Development
Product Layout
Product Schematic
Much of the recent progress we‟ve made in terms of product development is in revising the concept of
the Accharge so as to better fit the demands that our target market impose upon it. Initially we proposed
a device that consisted only of the wind-turbine functionality as the sole means of producing an electric
charge. This was due to the fact that at the outset of our project, we primarily focused on a portable
charger that could provide charge to cell-phones while in transit.
As we conducted further research however, we saw that there were additional needs from our initially
targeted market of frequent commuters who use public transportation beyond solely being able to
charge their mobile phones while traveling. One such need was the ability to make a phone call in an
emergency situation. From the results of our market research, we found that the consensus among
interviewees was that a phone call in an emergency situation was extremely important. Hence, we
proposed the idea of a hand-crank that could be used in the aforementioned emergency situations.
Moreover, we knew that the hand-crank would potentially be cheap to manufacture due to its simplicity
and inherent compatibility with the wind-turbine. Shortly after the conception of this idea, we came up
with the idea for a hand-pump extension to the charger that improved on the hand-crank idea (see
figures below). Whereas a hand-crank requires the use of two hands to operate it, a hand-pump requires
only one hand, thus allowing a user to potentially charge their cell-phone in one hand while
simultaneously making a phone call in their other hand, greatly speeding up the charging process.
However, we realized that the hand-pump would be significantly more complicated than the hand-
crank, so we did not discard the hand-crank idea entirely and instead left it as a backup plan if the hand-
pump concept proved to be unrealistic.
Hand-Pump Diagrams
A further component conceived by our team was a battery charging functionality that could fill in the
gaps voided by the wind-turbine and hand-pump/hand-crank functionalities. A wind-turbine may only
be used when a wind-supply is present and a hand-pump/hand-crank is meant only to be used in
emergency situations thus making it impractical to be used for prolonged periods of time. A battery
component successfully allows for hassle-free charging without a wind-source present for a prolonged
period of time. As such, this iteration of our product was a versatile device that allowed for charging in
various scenarios commuting professionals in Kerala would encounter.
Issues arose when we computed the cost to produce our product. Initially we set a desired retail price of
$20 for our product. Yet, when we tabulated the theoretical cost of producing our device we found that
it was $45.31, which was far too high to meet our desired price. While we acknowledged that this
estimated cost we had come up with was likely an over-estimate, we realized that we had to re-evaluate
our product if we wanted to keep prices down for our customers. One of our focuses was to avoid
providing consumers with unnecessary services. Thus, the decision to unbundle the product was made,
leaving only the wind-turbine as the basic component with the other components available as
purchasable add-ons. In this way, after re-adjusting existing costs with new accuracy and cutting the
other functionalities, we found that the cost of producing our basic unit was reduced to a more
reasonable $14.80. Thus, by allowing the customer to select only what functionalities they desire, the
overall cost is reduced for both us and the consumer, while greater customer satisfaction is achieved.
Because 10 weeks did not provide us with enough time to construct a fully functional prototype, we
decided to instead focus on creating test and lab prototypes that could show proof of concept for our
ideas. In conducting research online, we found that the hand-crank and battery cell-phone chargers
already existed (see images below) which proved to us that these ideas were indeed feasible.
Furthermore, a hand-pump powered flashlight also exists (see image below), indicating to us that a
hand-pump cell-phone charger is possible.
Because the wind-turbine was the lone component not previously proven, we conducted further
experiments to determine the practicality of using wind-power to charge a phone. A fan was connected
to a small electric motor so that it directly turned the shaft of the motor. Winds at various known
speeds blew through the fan, spinning the motor and generating an electric current whose voltage and
currency was measured. From this data, we generated a plot graphing the power output as a function of
wind speed.
From this data, we see that the power output is proportional to the cube of wind velocity. We observed
that the power generated at 15 mph (6.75 m/s) is .628 W. However, since power scales with velocity