Reply To: 80% Charge Limit occasionally charges to 100% — normal calibration cycle?
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Claire BennettA silent DFU-mode recovery attempt (error 4013/9) during overnight Finder sync over Wi-Fi will momentarily drop the USB-PD contract to 5 V/3 A, causing the battery gauge (gas gauge IC BQ27546) to lose its 80% set-point and fall back to full-charge termination voltage (4.44 V). Capture the handshake with log stream --style syslog --predicate 'eventMessage contains "USBPD" or eventMessage contains "AppleUSBTCPD"' --level debug while plugged in; look for PDO renegotiation followed by charge_limit_override = 1. Recovery: disable “Sync with this iPhone over Wi-Fi” in Finder, then run idevicediagnostics run --test=charging via libimobiledevice to re-flash the PD policy bundle.