Power Arduino with a cellphone

Step 2 Connect the cellphone to the arduino

Get your socket to plug into your arduino and situate it on the power area of the arduino so that it has connectors going from gnd, 5v, and 3v3. These are the only pins you will need to connect to. Solder the ground wire from your cell phone to the terminal of the connector that goes into gnd.(remove it from the arduino first!!) Then solder the +battery wire from the cellphone to a diode and then to the connector terminal going to 3v3 on the arduino so that the diodes stripe is on the arduino side. This diode prevents the arduino from trying to charge the battery when its plugged in. Now there should be an open terminal on your connector between the connected ones that goes to 5v on the arduino. We will need that later to charge the cellphone. If you want, you can stop here and it will work fine. You just won't be able to charge the cellphone by plugging in the arduino, you'll have to charge it with its own separate charger.