Intro...

If you are like me , Over the years you would have collected a few batteries from old mobiles or you would have had it because you replaced them.

Ever wonder what you could do with those old batteries ?? How about making a power bank from them ...?? Cool right .. in this instructable I will show you exactly that..So grab your goggles we are going to make something interesting..

Step 1: Getting Your Materials

Get the following materials ready

( very important)

1)Batteries

2)DC DC booster (i have the one withXL6001E)

3)Some wires

4)Soldering iron & flux

5)Diode

6)A charger

7)A female pin as per your charger

8)Female usb connector

9) A small plastic case to put the finished product in.

(Optional)

Check the image

Step 2: Preparing the Wires , Batteries and Soldering

Batteries

From each of the batteries cut a small part of the plastic dividers (as in fig)

and scratch the metallic part to reveal the shiny layer.

Wires

(These are important don't ignore)

Grab two wires of different colour (preferably red and black) and cut them into n parts (n=number of batteries) of about 5cm.

Strip the plastic from each side of the wire (for all of them).

And then tin the wires.

Apply some soldering paste on to the ends

Soldering

Place the wire over the terminals ( remember the colours ) and solder them on to the terminals.

This is tricky as the terminal doesn't get soldered well ..that's why I asked you to tin the wires and apply the paste properly .Removing a small part plastic of the plastic dividers help.

Testing

Test the conductivity with a multimeter .

Step 3: Connecting Things Up..

1) Connect all the batteries in parallel( Remember the colour code)

2)Connect the female charging pin parallel to the batteries , through a diode (Adjust the diode in such a way that it allows current only to come into the batteries and not out)

3)Connect the DC DC booster parallel to this arrangement (remember to connect it to the input terminals of the booster)

4)Connect the output to the power rails of usb female connector. (reffer the pin out from the fig)

5)Add a way to turn off the connection from the batteries (like a switch).

Step 4: Configuring the Booster

Connect a load resistor (any value) parallel to the output and leads of the multimeter.

And then adjust the booster till the multimeter reads 5 V.(see fig)

Also check the output frequency if your multimeter is capable of it.mine was 1.32 KHz so it certainly wouldn't destroy any appliance..(Higher the frequency it's less likely to produce any harmful ripples.)

Step 5: Packing It Up..

Look for a small case to keep all this inside.

You can drill holes for the charger and usb connector . and fit them all inside.

Personalise it the way you like.

Step 6: Use It !!..

Well congratulations...you have with you a custom built power bank!!

I used it to charge my Tab and to power my raspberry pi 2 to make it portable.

Do tell me how you customised it and used it...:in the coments :D

Step 7: Understand the Limitations!!

You have built a powerful power bank .. but do understand the limitations ..

1) If you are going to pull more than 2 A, consider adding a heatsink to the main chip as it can get very hot and cause damage.

2) Your batteries are not protected from over charging , over draining and over heating.....so as long as you take good care of it ... it should be okay.(That's why i suggested you to add a switch)

3) I have combined 3 , 1000mAh batteries so it should be 3000mAh at 3.7 volts ,but when you boost it to 5 v this capacity reduces, more so because of inefficient conversion (only about 85-90% for under 2 A).

But it's still a nice power bank that you have built, that you can boast off.

Psss..this is my first instructable please do provide feedback so that I can improve, also if you liked my instructable please vote me for the first time authors contest.

thank you.