We live in a constantly moving world in which mobile devices are our windows to social media, the internet and entertainment resources. The only problem is that those mobile devices don't have an unending battery supply. When they die, so does your handheld communication. How many times have you been stuck with a dead phone or tablet with no charging cable? A portable battery pack is the on-the-go solution for those moments when you need a quick charge.

External battery packs come in all different shapes and sizes, with different features and functionality. The best mobile battery packs combine high-capacity batteries with a small form factor and low weight, making them very portable. Most USB battery packs are compatible with all devices that charge via USB – just make sure you have the right cables to connect to the external battery pack's USB ports ;-)

But building ourselves a battery pack sound's fun... so here's an instructable..which guides you through few steps to build one yourself..This battery pack has a real small form factor and can be recharged using your smartphone charger or any power USB slot...you can use this as a portable power source for ardunio or raspberry pie projects also ...

enjoy making your own battery pack...!

Step 1: Components Required..

The main components required for the project, followed by a ebay link are given below ...

Li-ion batteries you can buy them here..!
dc-dc Booster module you can buy them here..!
charger module TP4056 you can buy them here..!

With this all you'll need is some soldering skills and a cup of coffee..!

Step 2: The Battery

No, these aren’t some sort of weird, blue AA battery, this is actually a 18650 Lithium Ion Cell. These round high capacity cells have been mainly used in flashlight type applications but with its capability to be used as a drop-in rechargable cell at 3.7V with a capacity of 5800mAh. This is a great battery option for those of you who need a simple to install and replace cell with a lot of juice.

These 18650 Cells have a standard discharge current of 0.2C to a maximum of 1C and can handle about 1000 charge cycles.The link i have given is of 3000mAh battery,,, but i was able to buy with a capacity of 5800mAh.

I have made a battery holder myself, you can actually buy it at any local hardware store , unless you like to get your hand dirty instead of, driving to the store..

I've actually used a PVC pipe cut it into half
glued two pieces of plastic on both ends
added 2 nut-bolts

and ta-da there it is ... a hand made battery holder..

Step 3: The Charger

hail TP4056,,,..!! a very small module for DIY people, it uses the TP4056 controller and standard configuration is with 1A charge current.The board needs a 5 volt power supply, this can either be from a mini usb connector or soldered directly to the board.

You'll find a good review on this charger module here..!

Specifications:

Charge module: Linear charging.
Current: 1A adjustable.
Charge precision: 1.5%.
Input voltage: 4.5V-5.5V.
Full charge voltage: 4.2V.
Led indicator: red is charging Green is full charged.
Input interface: micro USB.
Work temperature: -10℃ to +85℃.
Inversed polarity: NO.
Size: small around 25 x 19 x 10 mm.

Note :

Ampere meter can only be connected to 5V input end of the module.
It is better that the charging current is 37% of the battery capacity.
If you charge to the battery of 1000mAH, current of 400 is enough.
The connection wire should not be too thick.
Make sure the connect point is good.
If the input voltage is too high, like 5.2V, the current will be less than 1000mA, it is normal.
It is protection function, auto-substract the charging current to avoid burn damage to chip.
DO NOT CONNECT battery in reverse manner else circuit will burn,, u see this is the alternative use of this project..

Step 4: The Booster

Here is tutorial video which will help you understand how a DC-DC booster works...it;s basically the same principle of joule thief...A boost converter (step-up converter) is a DC-to-DC power converter with an output voltage greater than its input voltage. It is a class of switched-mode power supply (SMPS) containing at least two semiconductors (a diode and a transistor) and at least one energy storage element, a capacitor, inductor, or the two in combination. Filters made of capacitors (sometimes in combination with inductors) are normally added to the output of the converter to reduce output voltage ripple..

The Module Properties of one we are using :

non-isolated step-up module (BOOST)
input voltage: 2.5-4.9V
Output voltage: 5V
Output Current: the maximum 1000mA
Efficiency: Up to 92% (the higher the input voltage, the higher the efficiency)
Switching frequency: 1MHzOutput ripple: 20mV (MAX)
Operating Temperature: Industrial (-40°c to +85°c)
Voltage regulation: ± 2.5%Size:28*19*8mm(L*W*H)

Step 5: The Battery Pack

The connections are very simple, anyone with basic soldering experience can do it,,, the TP4056 charger circuit has two +,- connections, one with a capital B printed, those +,- pins should go to the battery where as the other set of +,- should go to the DC DC booster module. The DC DC booster module can use the battery when its being charger simultaneously, and the charger module can be hooked up to any wall output or USB output...
so there you go a portable battery with high capacity, using off the shelf components,,
you can properly arrange the components is box, to make it look nice, or fashionable..

Step 6: Performance

The battery pack charges full in about 8 hours of charging, thats alot but a battery with that type of capacity needs it.. Also discharge's after 4-5 cycles of charging a smartphone with 2200mAh battery..
there might be some heat dissipation problems, but can solved by adding a heat sink to the charger module..
overall the battery pack is quite efficient and cheap as compared to any other battery pack with that capacity..

you can check few of my other projects on my blog at :

scifiswapnil.weebly.com