Building the Charger
All you need is some electrical or duct tape, a key, a car charger for your device and the battery. You will notice that there is a little strip of metal that bulges out from the side of the plug that goes into the vehicle lighter. You want to align the metal key so that it comes into contact with this piece. This needs to be properly spaced so that it will plug into the positive terminal of the battery while the end of the charger plug fits into the negative one.
Once you have it properly aligned, simply secure the key to the charger with your tape. Electrical tape is best because it will help to maintain conductivity and prevent energy from dissipating into the air as the device is being charged. However, duct tape will also work very well if you don’t have any alternatives. Both of these tapes are strong enough to provide the adhesion that is necessary to keep the key in position. If the key falls out of contact with the metal piece, the circuit won’t be complete, and the phone won’t charge.
Now, all you need to do is to plug your makeshift charger into your phone and then connect the key and plug into the terminals on the battery. Make sure that the key always goes on the negative terminal. You can test this method simply by looking at the display on your phone. If it shows that it’s charging, then it works.
Keep in mind that the amount of juice that you can get from the battery depends on its quality and amount of power that’s stored inside. The size of your phone’s battery, and the amount of power you need will also determine how much of a charge will be available. However, during an emergency, a good 9 volt battery will give you enough energy to try and contact someone and obtain the assistance that you need.
You can also apply this method to any battery as long as you can make the connections secure. The reason the 9 volt is preferred is that it is easier to rig this setup since the spacing between the key and the charger plug fits the battery almost perfectly. But, feel free to try and tape and secure a different battery if that is all that is available to you at the time. The important thing is that you have this easy option to charge your devices if there are no traditional outlets or power sources nearby.