Direct charging of battery bypassing internal circuit
This picture says most of it:
I want to connect a li-ion battery charger directly to the 4S battery, without removing it from the phone. This white plug shown touches the back of the pins 1 and 4 on the battery connector.
Will this work, or is the path of least resistance away from the battery, which could result in a short circuit? I'm currently looking at the schematics to try and make up my mind about this.
(I do this because there is something broken in the phone's internal charging circuit that I have been unable to solve. And yes, that red sticker is a good clue :))
Here is the full setup. I kept the phone on while attempting, and I can confirm that it works. I have so far tested charging the phone from 10% to 30%.
This phone does not charge through the charging cable. I kept it in anyway because the phone does notice it being plugged in. I haven't yet tested leaving it unplugged while charging.
The white plug is simply two small jumper wires with a third empty jumper head (just the plastic) between them. The distance turned out to match perfectly with the pins on the battery connector. I taped all of this together with electrical tape, then also taped most of the pins so they wouldn't touch any other metal surface in the iPhone.
Those jumper wires are simply connected to the + and - terminals of a 4.2V/800mA battery charger, which has all of the important safety components.
I was also lucky to find a plastic piece that allowed me to strap the plug at just the right angle.
With this, I can keep using the water-damaged logic board and charge the battery without removing it every time.