Chosen Solution
Hello, i had a family member’s iphone 5s that has been used with a bad charger for a long time. The phone would not charge/start if battery was completely dead, and when a full or partially charged battery was placed,the phone would start and accept charge but would discharge quickly after that on its own.
So i ordered a new U2 IC chip and replaced it. U2 replacement worked fine and the phone would start with a charged battery BUT would not detect the charging cable at all. I think in the process i chiped/damaged the Q2 chip. So i removed the old Q2 chip and put a jumper in the 3 contact points. Now phone boots up normally and it detects the cable and charges up fine.
The problem is the battery level reports 100% all the time until it actually runs low after hours(lets say the true percentage is 15%) and starts counting backwards from 99% down to 1% and shuts down. If I plug the charger in, lets say at 4% ,the percentage will normally start going up until it reaches 100% and stays there, until low-battery of course.
What could be the problem? Could it be a bad q2 jumper? I luck the microscope to see if all 3 points are connected ok, but phone works and charges so I guess they are fine… Could it be a battery problem or maybe some u2 contact points that haven’t been soldered ok? What part of the phone is actually responsible for measuring the battery percentage? Notes: The battery I used was a completly new one. I put a youtube video to play(and test the battery) and played normally for about 5 hours until it shutdown.Seems normal battery life to me. I am in NO way professional but i like DIY stuff.I only have a cheap hot air gun and a cheap soldering iron but i luck the microscope for precision. Thanks in advance.
That is the problem of SWI line see resistance near battery connector might be open.This SWI line is connected to Tigris then CPU.
