The document discusses power banks, including what they are, how to charge them, and how long they last. It provides the following key details: 1. Power banks allow you to store electrical energy from a wall outlet or computer USB port to later charge mobile devices using a portable battery. They can charge devices like smartphones, tablets, cameras and more. 2. To charge a power bank, use the mini or micro-USB charging port and plug it into a wall outlet or computer USB port. Larger capacity power banks take longer to charge fully than smaller ones. 3. The lifespan of a power bank depends on its quality and how many charge/discharge cycles it can perform, typically over 500

1. QUEZON CITY POLYTECHNIC UNIVERSITY
Department of Information and Communications Technology
673 Qurino Highway, San Bartolome, Novaliches, Quezon City
POWER BANK
Members:
Florlyn Bersamin
Juan Carlos H. Caraan
Jason Cortel
Mel Ergina
Eric sison
Felipe T. Varon Jr.
Joshua Velasco
Submitted to:
Prof. Joan F. Lawan

2. QUEZON CITY POLYTECHNIC UNIVERSITY
Department of Information and Communications Technology
673 Qurino Highway, San Bartolome, Novaliches, Quezon City
What is a Power Bank and what can they charge?
Portable Power Banks are comprised of a special
battery in a special case with a special circuit to
control power flow. They allow you to store electrical
energy and then later use it to charge up a mobile
device. Power Banks have become increasingly
popular as the battery life of our beloved phones,
tablets and portable media players is outstripped by
the amount of time we spend using them each day.
By keeping a battery backup close by, you can top-up
your device(s) while far from a wall outlet.
The Power Banks we're talking about are good for almost any USB-
charged devices. Cameras, Portable speakers, MP3 players, smartphones
and even some tablets can be charged from a Power Bank
How do I charge a Power Bank?
A Power Bank will have a dedicated input socket for
receiving power. This power can come from a USB socket
on your computer, but may charge faster when using a
wall socket adapter. We most often see Power Banks use
a Mini or Micro-USB socket for charging, and full-sized USB
sockets for discharging. On very rare occasions, Power
Banks can use the same socket for input and output, but
this is rare and should not be assumed of any Power Bank,
as trying to force power into an output can damage the
battery. Always check the manual for specific instructions if
you're not able to find a clearly marked input socket.
Depending on the capacity of the Power Bank and its
current charge level, it can take quite a while to fill up. For
example, a 1500mAh rated Power Bank should take about the same time as
your typical smartphone to charge. For larger banks, this time can be
doubled, tripled or quadrupled. Most Power Banks have both an LED
indicator to show when they are at capacity, and a safety cut-off to prevent
overcharging and overheating. Whenever possible, remove the Power Bank
from charge when it is full, or at least avoid leaving it connected long-term
after it’s full. Ambient temperature and power flow will also affect charge
times, so it's best to keep it topped off regularly.

3. QUEZON CITY POLYTECHNIC UNIVERSITY
Department of Information and Communications Technology
673 Qurino Highway, San Bartolome, Novaliches, Quezon City
How long does a Power Bank last?
This is a bit of a loaded question. There are two important life
expectancies to consider:
1. The number of charge/discharge cycles a Power Bank can reliably
perform in its lifetime.
2. How long a Power Bank can retain its charge when not in use?
The answer to point one can differ between models of Power Bank, their
internal components and the quality of their manufacturing. We try not to
stock Power Banks which have fewer than 500 charge cycles in them. This
would allow you to charge a device from the Power Bank every day for a 1.5
years before it started to lose its ability to hold charge long-term. Better and
more expensive Power Banks can last longer, while smaller and cheaper
units may fall short depending on their treatment. Power Banks are
generally not used daily, so they often last much longer than 18 months in
real-world usage patterns.
Point two depends on the quality of the controller circuitry and battery
cells. A good Power Bank can hold charge for 3 to 6 months with minimal
loss. Lower quality Power Banks may struggle to retain a useful charge more
than 4 to 6 weeks. In this regard, you get what you pay for, and if you need
a long-term emergency power supply consider increasing your budget to
ensure you're not going to be caught short. Most Power Banks will slowly
lose charge over time, to a degree influenced by the environment and their
treatment. For example, leaving a Power Bank in the car where the
temperature can fluctuate greatly over time can shorten its lifespan.
Things that you should know about Powerbank
1. Numbers at power bank
In power bank the number are indicate from total battery cell capacity.
More cells means more power that can be saved and ready for backup your
device. How many time power bank can recharge the device is depend on
power bank capacity. If you have power bank with 12.000 doesn’t mean you

4. QUEZON CITY POLYTECHNIC UNIVERSITY
Department of Information and Communications Technology
673 Qurino Highway, San Bartolome, Novaliches, Quezon City
can recharge 2000 mAH battery for 6 times. Some electricity will be lost due
the conversion and recharge.
Power bank have 3.7 volt for device recharge and 5 volt for recharge it’s
own battery. This is the conversion formula
(Power bank capacity x power bank voltage) : needed voltage
As an example, power bank with 8.800
(12.000 x 3.7) : 5=8.880
If we calculate the loss power at recharge is 10%, then 8.800 minus 10%
and we got 7.992
So, we got a conclusion that power bank with 12.000 mAh only have 7.992
mAh capacity. Each time the power bank recharge the device need 2.000
mAh, then with 12.000 mAh power bank only can recharge for 4 times with
assumption the last one will not got 2.000 mAh
2. Powerbank plug
Usually we saw there 2 port in power bank ,1A and 2A. This number
show how much power that will use for recharge troughs that port. A means
ampere. The power that will use for charging will determine how long it
takes full recharge. As an illustration, Samsung Galaxy III have 2.100 mAh
battery then it recharge from 1A output port, it will took around 2 hours for
fill the battery. Using 2A is not quarantine that the recharge time will cut for
half. Some device has power restriction that can use for recharge. But in
support device, it will cut time to half.
3. The battery (power storage)
For power storage, power bank using battery. There is two type
1. Li-Polymer battery
This kind of battery usually have 2500 Mah. The old model power
bank using this battery. This type has bulky body.
2. Li-Ion battery
Power bank that using lithium battery has slight body. Lithium
battery has minimum capacity 8.000 mAh.

5. QUEZON CITY POLYTECHNIC UNIVERSITY
Department of Information and Communications Technology
673 Qurino Highway, San Bartolome, Novaliches, Quezon City
Materials in making a Power bank
 1 Battery (7.4 V, 4200 mAh)
 1 Switch (2 sterned)
 2 Capacitors (1 1000 uF/16 V, 1 470 uF/ 16V)
 1 Resistor (150 ohm)
 1 small bulb (LED)
 1 Regulator (LM 7805)
 1-2 m of solid wire
 1 USB plug (10v/1 a) - for iput
 1 Micro-USB plug (5v) – for ouput
Other Materials
 1 Case (insulating type)
 Pliers
 Soldering iron and lead (and soldering pump if needed)
 Glue gun and glue stick
 Pencil/ pen for marking
Schematic Diagram
Legend
Symbol Meaning
BT1 Battery
C (2,3) Capacitor
R1 Resistor
D1 LED
U1 IC
SW1 Switch
INPUT USB
OUTPUT Micro-USB

6. QUEZON CITY POLYTECHNIC UNIVERSITY
Department of Information and Communications Technology
673 Qurino Highway, San Bartolome, Novaliches, Quezon City
(Figure1)
Steps in Making a Power Bank
1. Test each component via (multitester etc.) to see if working or not.
2. Position all the components on how they should be placed inside the
designated case, mark their positions.
3. Cut holes (based on your preference)for the external connections (if there
are any).
4. Connect all the components based on the diagram presented on figure 2.
5. Test the Circuit.
6. If the circuit fails repeat or recheck the steps 1-3, if it works proceed to step
number 7.
7. Solder all the connections to make it permanent.
8. Repeat step 5.
9. Position all the components in the case but this time, glue them on the
marked area to make them permanent.
10. Repeat step 5.