Chosen Solution

Disclaimer: this question might show a complete lack of understanding of the finesse of electronics. My iPhone 4S’ charging circuit is not working properly, so I am looking at convenient ways of charging the battery outside of the phone. I’ve found a circuit diagram posted here by oldturkey03, and I will give that a shot. Then I had another thought; I do have old li-ion chargers, for digital cameras and such. If one of these has the correct voltage (3.7V) and the correct current rating (<=1000mA), would it be up for the task, or could this still break my battery? Update I’ve been using this setup many times now and it’s working great:

I have very simply connected the + and - terminals of the charger to the corresponding pins of the battery. Most of the jumper cables are used to keep the battery in place. By a strike of luck, the small jumper wires fit very well into the battery plug.

cerapter, as long as it provides some kind of overcharge protection, it should be okay. Consider getting your iPhone repaired so you do not have to do this for very long. Could become a royal PITA to external charge it.