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| How to Repair iPhone 12 Pro Max that does not detect battery and does not charge | |
|---|---|
| Device | iPhone 12 Pro Max |
| Affects part(s) | Main Logic Board |
| Needs equipment | Soldering Iron, Hot Air Station, Tweezer, Flux |
| Difficulty | ◉◉◉◉ Specialist |
| Type | Soldering |
Problem Description
An iPhone 12 Pro Max shows no charging and battery not detected, even after replacing the charging port, using a new cable and charging cable/brick.
- Battery connector voltage (BATT_VCC) reads 3.7–4.0 V (normal).
- Charging IC and USB IC measure fine.
- Battery FPC diode readings normal.
Root cause: low I²C voltage (0.2V instead of 1.8V) on SDA/SCL pins.
Tracing these lines leads to U2470, the battery data level translator IC.
Replacing U2470 restores I²C communication, allowing the phone to detect the battery and charge normally.
Symptoms
- iPhone does not charge or power from the battery.
- Battery percentage not displayed, device may only run on DCPS.
- No corrosion or damage visible on battery connector area.
Diagnostic Steps
- Measure Battery Connector Voltage
- BATT_VCC → 3.7–4.0V = ✅ Good
- If missing, diagnose power path first.
- Check Battery FPC Diode Mode
- All lines read within normal range = ✅
- Measure I²C Lines (SCL/SDA)
- Expected: ~1.8 V
- Observed: ~0.2 V → indicates line is being pulled low.
- Trace I²C Lines to U2470
- Locate U2470 (near battery FPC).
- Check for damage/corrosion.
- If clean, suspect internal short or failure pulling bus low.
Repair Steps
1. Remove Faulty U2470
- Use hot air station to remove U2470.
- Clean pads, inspect for shorts.
2. Replace U2470
- Install a new/reballed U2470.
- Align carefully.
3. Verify Voltages
- After installation, re-check I²C voltage at battery FPC:
- Should now be ~1.8V.
4. Final Test
- Connect battery, boot phone.
- Confirm battery is detected, percentage shows, and device charges.