This is a way to increase battery capacity so your phone will last longer without the need for buying more expensive extended batteries.
small gauge wires
Extra Battery with same voltage as cell battery
Also bear with me because this is my first Instructable and while I planned on taking more photos as I will explain in the steps that didnt happen. For demonstration I am using an old cell phones battery to help with some steps.
Please let me know if you have any questions, comments or suggestions.
Disclaimer: Lion Batteries can be dangerous and even more dangerous when messing around with them when doing this be careful and wear protective gear. I am not responsible anything that results from this. Also I assume this is warranty voiding.
Step 1: Deconstructing
Take battery out of phone and put it aside. Now take the second battery and remove the protective wrapper(tagged as 1) on the battery and you should see a the battery. In my case the casing was the +. Carefully remove the black thing that holds the circuitry(2). You wont need the circuitry or terminal for the this battery.
Step 2: Connecting Batteries
We want to connect these batteries in parallel positive to positive and negative to negative. Be careful because these batteries will spark and can be damaged when shorted and remember that the whole casing is a connected as a terminal. The tricky part is revealing the terminals under the original battery while not damaging* the circuitry. If you carefully life the circuitry casing up you can reveal the negative terminal. Connect the batteries in parallel and use electrical tape to ensure there are no shorts. I just used the casing to connect the two positive terminals.
*Note: I do mean carefully I accidentally ripped the terminals off the circuit board and though I destroyed it. Luckily I didn't give up and with some soldering work I managed to rewire everything but it was not easy. Because of that I was a little frantic and didn't end up taking pictures all the way through.
Step 3: Wrapping Up
Now tape everything up and put it back into the phone securely and ensure there are no potentials for shorts. Then to accommodate for the second battery cut out a whole in the back of your phone and case. Make sure to sand down edges.
That should be it. Feel free to ask questions.