# PowerBanks How It Works. Rohs power bank 10000mah

## PowerBanks How It Works

Powerbanks are becoming popular these days as our gadgets or devices were all getting smarter versatile tools in our daily lives specially for various types of communications such as calls,SMS,emails and other task,and these Smart devices (smartphones tablets) needs more power for them to work and last for a day as they should be. Normally the devices that needs a back up power are the smartphones tablets these days.And most of us individually owns one.But not all people knew how powerbank works literally.And some sellers just don’t explain on how their Powerbank works.And many people just end up buying the wrong specifications of powerbank that suits the need of their devices (such as smartphones tablets).That’s the reason I made this and compiled some facts gathered from different manufacturers and blogs site ,and made it into one instructables that may help some DIY’ers who planned to build their own powerbank or just buy the right one.

## Step 2: Choosing the Right Powerbanks:

1.How do I know which powerbank suits my device? Depending on individual needs and requirements, there are several general criteria to consider when selecting a powerbank: a) Capacity For example if your phone battery is 1500mAh and is 0% now, a powerbank with 2200mAh can charge your phone 1 time. If your phone battery is 3000mAh and is 0% now, a powerbank with 2200mAh will not be able to charge your phone to full because the phone battery capacity is higher than the powerbank. If you require a powerbank that is able to charge your phone several times, you need a powerbank with higher capacity. b) Number of output 1 output to charge 1 device, 2 outputs to charge 2 devices. c) Output specification 1A-1.5A output is generally for smartphones, 1.5A-2.0A output is generally for tablets. 2. How long do I need to charge the powerbank for the first time and subsequent time?/ How many times can a powerbank charge my phone? a) Powerbank is already pre-charged and ready to use. b) Re-charging time depends on the capacity of the powerbank, remaining power in the powerbank and the power supply. Example:.Powerbank: 13000mAh (0% remaining).Power Supply/ Input: 1000mA plug.Calculation: 13000mAh/ 800mA = minimum 16.25 hours (Why 800mA? An estimate of 20% power is consumed during the charging/ discharging process) c) Similar formula applies to calculate number of times a powerbank can charge a phone. Example:.Powerbank: 10000mAh (full at 90%).Phone Battery: 1500mAh.Calculation: (10000mAh x 90% x 80%) / 1500mAh = up to 5 times (Why 90%? Assuming the power bank is well maintained in good working condition and can conserve up to 90% power) (Why 80%? An estimate of 20% power is consumed during the charging/ discharging process) Note that the calculation is based on normal condition whereby the powerbank or device (phone/ tablet) is not in use during charging process. A running device generally consumes power therefore if your device is actively in use during the charging process, the charging performance may not meet the expectation. The above calculations are examples made simple for easy reference. Accuracy may vary.

Images in order1.commercial PB (upgraded from 1200 to 2800 mah)2.commercial PB Kit(modified by adding switch and upgraded 2400 to 4000mah)3.commercial PB under my testing.

## Step 3: Homebrewed Powerbanks

Image1-using 8 AA Nimh 2800 mah batteries Image2-using 318650 2200mah Li-ion batteries

ibles can be found on my DIYs

## Step 4: Difference Between Li-ion and Li-Po

Lithium-ion batteries use a variety of cathodes and electrolytes. Common combinations use an anode of lithium (Li) ions dissolved in carbon or graphite and a cathode of lithium cobalt-oxide (LiCoO2) or lithium manganese-oxide (LiMn2O4) in an liquid electrolyte of lithium salt. Because they use a liquid electrolyte, lithium-ion batteries are limited in shape to either prismatic (rectangular) or cylindrical. The cylindrical form has a similar construction to other cylindrical rechargeable batteries,Prismatic batteries have the anode and cathode inserted into the rectangular enclosure. The image link at illustrates this construction method. Lithium-Ion-Polymer batteries are the next stage in development and replace the liquid electrolyte with a plastic (or polymer) electrolyte. This allows the batteries to be made in a variety of shapes and sizes. The significant advantages of lithium-ion batteries are size, weight and energy density (the amount of power the battery can provide). Lithium-ion batteries are smaller, lighter and provide more energy than either nickel-cadmium or nickel-metal-hydride batteries. Additionally, lithium-ion batteries operate in a wider temperature range and can be recharged before they are fully discharged without creating a memory problem. As with most new technology, the disadvantage is pricing. Currently, lithium-ion and lithium-ion-polymer batteries are more expensive to manufacture than standard rechargeable batteries. Part of this expense is due to the volatile nature of lithium. Lithium-ion batteries are most commonly used in applications where one or more of the advantages (size, weight or energy) outweigh the additional cost, such as mobile telephones and mobile computing devices. Lithium-ion-polymer batteries are used when the battery needs to be a particular shape. Lithium-Ion Battery Characteristics Type Secondary Chemical Reaction Varies, depending on electrolyte. Operating Temperature 4∫ F to 140∫ F (.20∫ C to 60∫ C) Recommended for Cellular telephones, mobile computing devices. Initial Voltage 3.6 7.2 Capacity Varies (generally up to twice the capacity of a Ni-Cd cellular battery) Discharge Rate Flat Recharge Life 300. 400 cycles Charging Temperature 32∫ F to 140∫ F (0∫ C to 60∫ C) Storage Life Loses less than 0.1% per month. Storage Temperature.4∫ F to 140∫ F (.20∫ C to 60∫ C) ï The chemical construction of this battery limits it to a rectangular shape. ï Lighter than nickel-based secondary batteries with (Ni-Cd and NiMH). Lithium-Ion-Polymer Battery Characteristics Type Secondary Chemical Reaction Varies, depending on electrolyte. Operating Temperature Improved performance at low and high temperatures. Recommended for Cellular telephones, mobile computing devices. Initial Voltage 3.6 7.2 Capacity Varies depending on the battery; superior to standard lithium-ion. Discharge Rate Flat Recharge Life 300. 400 cycles Charging Temperature 32∫ F to 140∫ F (0∫ C to 60∫ C) Storage Life Loses less than 0.1% per month. Storage Temperature.4∫ F to 140∫ F (.20∫ C to 60∫ C) ï Lighter than nickel-based secondary batteries with (Ni-Cd and NiMH). ï Can be made in a variety of shapes.

## Step 6: Powerbank Accesories

image 1. bundled with commercial Powerbanks.image 2- additional(option only) accesory to extend compatibility to any devices.