Wireless charge sharing between two mobiles using wireless transceivers

1. WirelessCharge Share Between Two Mobiles
Y. Mohith1, Modupalli Joshna 2, C. Manisha3, K. Kathik Kashyap 4, Chetana Tukkoji 5
1,2,3,4 B.Tech IV year Students, Dept. of CSE, GITAM School of Technology, Bengaluru.
5Assistant Professor, Dept. of CSE, GITAM School of Technology, Bengaluru.
ABSTRACT
Battery charging technology is extremely
important in today’s mobile and wireless
industry. Battery can effect size, dimension, cost,
and the usage of many consumer electronic
devices. The process of battery charging must be
reliable, safe and fast. This paper introduces a
new application of wireless power transfer,
enabled by our re-configurable bi-directional
wireless power transceiver chips. Here, two
re-configurable wireless power transceivers,
which reuse almost all of the hardware, are
briefly discussed.
Keywords: WPT, Battery, Circuits
1. INTRODUCTION
Wireless Power Transfer (WPT) has been
utilized in a wide range of applications,
including mobile, wearable, implantable
devices, and wireless sensor networks. In
consumer electronics, wireless charging
function had been integrated with the
wireless charging function. Meanwhile, after
the market wireless charging components are
quite mature now.
In public places people may charge their
mobile phones without any effort by using
WPT technology, e.g. coffee shops and
restaurants. Also, WPT technology has a
large potential to help the devices to be
thinner and waterproof by removing the last
connector. Because the power connectors
quite often will limit the thickness of the
devices, and will easily wear out in humid
environment [3]. Therefore, it is predictable
that the number of electronic devices are
furnished with a wireless charging function
will experience an exponential growth [1].
Figure. 1.1. Projected wireless charging
eco-system based on reconfigurable
bidirectional wireless charging.
From the Figure 1.1, it was found that the
wireless power receiver (RX) can simply
reverse its operation direction and become a
wireless power transmitter (TX). The
bidirectional feature has been mainly studied
for electric vehicle (EV) applications [2]-[4],
although these were achieved with bulky
discrete components, typically working at 20
kHz, with several kW of output power and
>80% efficiency. For instance, [2] proposed
to control the wireless power flow using
phase or magnitude modulation, while [3]
used a self-resonant pulse width modulation
scheme to reduce circuit complexity. On the
other hand, a simultaneous data transfer
scheme was investigated in [4] via the same
coil. Considering the scope of consumer
electronics, bidirectional wireless charging
with monolithic on-chip implementation is
also highly favourable, allowing the
reutilization of the silicon-area-consuming
power transistors and the LC tank with
almost no cost. Then, the battery-to-battery
(B2B) charging can take place in, but not
limited to, the following scenarios:
1) Mobile phone to mobile phone charging;
2) Using mobile phone to wirelessly charge
wearable devices; or
3) Using a designated portable energy source
to charge low-power sensors for industrial
applications.
Consequently, Figure. 1.1 shows a projected
future wireless power eco-system comprising
four layers. The first layer is the fundamental
layer constructed by wireless charging pad
which is connected to the AC mains for fast
charging and multiple-device charging. The
second layer is an intermediate layer formed
by wireless power banks which gets energy
from the plant feeding the power-hungry
mobile devices.
The third layer incorporates mobile devices
with computation and analysis capabilities,
including notebooks, tablets and mobile
phones. The fourth layer contains low power
wearable’s and wireless sensor nodes, which
sense and collect the data from the human
body or the ambient environment[2]. To
facilitate these applications, this work
investigates for the first time an on-chip
solution for bidirectional wireless charging.

2. 1.1 Problem Statement: Wireless charge
sharing between two mobile phones is
limited to few mobile devices.
1.2 Objectives:
The main objective of this project is to
provide Wireless charge sharing between
any mobile phones (even to the devices
which are not capable of wirelessly charging
the phone).
1.3 Hardware Requirements:
i. Two Transmitters and receivers
ii. Two OTG cables.
2. LITERATURE SURVEY
2.1 EXISTING SYSTEM
(This system is present only for fewer
device eg: Samsung S10)
The MOBILES cannot get ready
immediately if they have run out of battery
energy. To overcome this, what the owners
would most likely do is to find any possible
opportunity to plug-in and charge the
battery. It really brings some trouble as
people may forget to plug-in and find
themselves out of battery energy later on [3].
The charging cables on the floor may bring
tripping risks. Leakage from cracked old
cable, in particular in cold zones, can bring
additional risky conditions to the owner.
Transmitter Section:
Figure:2.1.1 Transmitter Section
The Figure 2.1.1 contain the following:
 The transmitter is a mobile from
which the charge is to be
transferred.
 Once the circuit is initiated, the
charge from the transmitter mobile
is converted into DC using Diodes
and Capacitors .This DC current is
given as an input to microcontroller.
 Here we use a Crystal oscillator of
10MHz to tune the microcontroller
kit.
 We have a relay and a relay driver
which is used to transfer the
required charges to the WPT
section.
 This WPT in-turn heats up the
primary coil in the transmitter
section.
 RS232 interface is used in the
transmitter section in order to make
efficient interface for transferring of
data over the components.
Receiver Section:
Figure: 2.1.2 Receiver section
The Figure 2.1.2 contains the following:
 In the receiver mobile, the
secondary coil is induced when the
primary coil (transmitter mobile) is
brought near to it.
 The current produced due this
induction is given as an input to the
receiver module.
 This current in-turn initiates the
receiver circuit, a voltage regulator
is used in order to tune the required
voltage.
 We use a PIC Microcontroller to
interface with the external peripheral
devices.
 We made output port as the USB
port, so when the current is
regulated and supplied by the circuit
the mobile at the other end of the
USB gets charged.
2.2 Advantages
The Architecture is embedded inside the
body of mobile device.
 Quick- Though all types of USB
chargers supply an adequate amount of
power to charge the cell phones, there
are also few which are far powerful and
efficient than others. This type of
chargers has the ability to charge the
mobiles phones in a far efficient way
than ordinary ones. This is why it is
advised to check the output
specifications of different chargers in
order to select the right one for your

3. mobile. If the mobile charge is not
efficient enough to charge the phone, it
may be possible that it will charge the
phone. But, it finishes the recharge even
more quickly.
 Convenient -The size, charging ability,
and compatibility of the USB mobile
phone charger makes a great option for
the users to carry to other place. Even
when forgot to carry the adaptor of the
charger, you can connect the USB wire
with the power bank or laptop to
recharge your phone during the outdoor
trip.
 Compact-A USB mobile phone charger
requires very little space as compared to
wall and car chargers. The wall charger
cconsists of an adaptor node at one side
of the charger. This is the place where
the conversion from AC to DC. Most of
the car chargers, on the other hand,
comprise a massive portion on one end
of the charger in order to fit perfectly
on the car’s dashboard. The USB
mobile chargers usually have a short
length wire with a small connector at
both ends. You can disable the USB
cable from the adapter in order to place
it into the purse and laptop case.
2.3 .Disadvantages
The limited devices can only transfer charge
between those set of devices.
 Damage- Another physical constraint
of wired technology is that wires can be
easily damaged, which is not as large of
a concern with wireless technology.
Exposed cables are receptive to
everyday abuse from things such as
cleaning. Wires that are exposed and
not properly laid may also pose a
tripping hazard, not only damaging the
cable but also potentially sending
someone to the emergency room.
Damaged wires should to be replaced
completely.
 Device Cost-Wired technology costs
can be very expensive when used in
large buildings. This is especially true
when locating cables underground or
running them through multiple stories
of a building. Depending on the size
and scope of the job, professional unit
may be needed to install wired
networks for your business. In
comparison, wireless technology would
not require expensive underground
cables or any notable damage to
building structures such as a hole in
walls or ceilings.
 Expansion-The scalability of wired
technology is costly and time
consuming. It may even interrupt work
flow as crews rewire areas within the
office. In comparison, wireless
networks can be set up relatively
cheaply using multiple access points
without the need for significant
alterations to a building.
2.4 Proposed System
To overcome the disadvantage of the wired
charging system we use wireless charge
transfer between two devices which one act
as transmitter and other act as receiver.
Android app and Bluetooth is used to control
the other device. If we press the button ON
in transmitter device, it indicates that the
charge is transferring to the receiver device.
If we press the button OFF in transmitter
device, it indicates that there is no
transferring of charge. Liquid Crystal Device
is used to display the information regarding
the receiver device whether charge is
transferring or not from transmitter to the
receiver.
1. It is easy to implement
2. It has more efficiency
3. No need for grids and substations
4. It produces low maintenance cost.
5. More effective when the transmitting
and receiving points are along a line of
sight.
6. It can reach the places which are remote
3. System Architecture
Figure: 3.1 System Architecture
As shown in the above Figure 3.1 We need
two Transceivers, and two mobile phones.
There should be an android app to share the
charge between two mobile phones [2]. Here
the transceivers plays a major role on
connection between two mobile phones
where these transceivers should be placed on

4. each phone. The next step is to connect the
phones through the android app and after
that we should place one mobile on the other
to share the charge.
3.1 Disadvantages
 Efficiency-The efficiency of the
wireless charging board is low, and the
charging efficiency may be between
30% and 80% depending on the design
and the location of the user’s cell phone
on the charging board. That is to say,
even in the ideal state, 20% of the
electricity can be useless. Even though
charging efficiency has been increasing,
the efficiency of high power charging
(such as mobile phones) is always
greater than low power charging (such
as electric vehicles).
3.2 System Analysis and Design
Wireless charging technology which enables
to charge your phones without them actually
being in contact. We don’t require the bulky
and long USB to attach every time to your
phone to get your phone charged but through
this technology, the power is transmitted
through free space in the process of wireless
charging. For the first half of the article we
go over high school physics, which is behind
this cool technology.
How does it actually work? Mobile chargers
are used to transform the alternating Ccurrent
from mains to required DC levels and then
after certain rectification and filtration
process the DC levels are fed to the battery
for the charging purpose [5]. In conventional
charging, the charger supplies the power to
the charging circuit of the mobile through a
conducting medium (a USB cord) but
assume a case where this transfer of energy
from charger unit to charging circuit happens
without externally the requirement for a
physical medium?
The principle of magnetic resonance, or
Inductive Power Transfer (IPT) is the basis
for Wireless charging. This process of
transporting an electrical current through the
use of coils between two objects can be
achieved to induce an electromagnetic field.
So, understanding the Concepts behind the
wireless charging Technology, we have to go
get similar with the terminologies associated
with it. The Energy transfer from the charger
to Mobile is processedd by mutual induction,
governed by the Faradays law of Induction.
BLOCK DIAGRAM
Figure:3.2 Block Diagram
CONCEPTOFWIRELESS CHARGING:
The steps associated with the process of
Wireless Charging are: Let’s break the
complete charging process into two circuits:
Transmitter & Receiver Circuit
The main aim of the Transmitter circuit is to
transform the received voltage into
high-frequency AC. After the high-frequency
current is generated by the transmitter circuit
it is fed into the transmitting coil in the every
circuit. As the high-frequency alternating
current is relinquished through the coil, it
induces the magnetic field in the coil and the
coil now operates as an electromagnet in
accordance with the 2 and Law of
Electromagnetic Induction.
Figure:3.3 Working of transmitter and
receiver coils
From the Figure 3.3, as the magnetic field in
one coil changes, and if the other coil is

5. placed in the sufficiently close distance, the
emf will be inducted into the neighboring
coil. The alternating current induces
alternating flux in the transmitting coil which
induces alternating magnetic flux in the core.
Now, again the reversed phenomenon take
the induced magnetic field in the Receiver
coil and generates the alternating current into
the receiver circuit in accordance with the
faradays Law of induction [4]. Hence the
energy is transmitted from the Transmitter
circuit to the Receiving circuit through
induction or coupling .Now in the last step,
the induced alternating current is converted
into required DC Voltage through a series of
rectifiers and filters. For charging at last the
Stable current is fed into the battery.
Consequently, in this way, the wireless
charging takes place.
Design and Connections: The two wires
from the receiver are connected to the two
wire to OTG cable that is connected to the
receiver phone. And the two wires from the
Transmitter are connected to two wires of
another OTG cable which is connected to the
Sender phone. If the connection that is made
is correct than a red light appears at receiver
end the connection is c1orrect and the charge
is being transferring
4. RESULTS AND DISCUSSION
The results of wireless charge share between
two phones are as shown below:
Figure 4.1 represent that the charging from
one phone to another phone is getting
transmitted using the transmitter and the
receiver. In the image below the charge of
one of the mobile is 49% and is getting
charged using the other phone.
Figure:4.1 Current state of battery
percentage
Figure:4.2 Battery percentage after charge
transfer
From the Figure 4.2 we can see that the
charging from 49% is increased to 50%. It
takes some 3-4 mins to get charged .It is
used in case of any emergency situations.
The result can be seen above.
5.CONCULSIONAND FUTURE WORK
“Wireless Power Transfer for Mobile Phone
Applications” has been successfully design
and implemented [2]. The wireless power
transfer provides an industry standard
between power transmitters and receivers
based on inductive coupling at proximity
with well aligned coils. The standard
provides a high design freedom for receivers
and the means to control power transfer; this
allows meeting the requirements of various
mobile device applications both
commercially as well as functionally.
Confidence in achieving interoperability is
achieved by limiting the design freedom for
transmitters in the early phases of releasing
the standard.
The component that we developed, can be
used in 2 ways, i.e., either as external
component or as internal component. This
entire circuit when designed and made Nano
it will be hardly in the size of 6cmx3cm. So
it can easily be made as a design in the
backside of the mobile (internal component).
This can also be used as an external device
that has a USB output port, the input for this
device will be the charge from the mobile
from which charge is to be transferred.
Whatever may be the device that is
connected at the other end of the USB port
gets charged easily.
REFERENCES
1. https://www.mepits.com/project/171/wir
eless/wireless-power-transmission-mobile-c
harger-circuit-using-inductive-coupling
2. https://medium.com/swlh/wireless-chargi
ng-c0a35351ffe8
3. https://www.researchgate.net/publication
/326701549_A_Working_Model_for_Mobil
e_Charging_using_Wireless_Power_Transm
ission
4. https://www.electronicdesign.com/power
/wireless-charging-technologies-transformin
g-mobile-world
5. https://nevonprojects.com/wireless-mobil
e-charging-project/