80% Charge Limit occasionally charges to 100% — normal calibration cycle?

The 80% limit is enforced by the power management firmware (PMGR) but a liquid-detection event in the Lightning/USB-C port forces a safety override that disables charge limiting until the next full reboot — check log show --predicate 'subsystem == "com.apple.iokit.power"' --info | grep -i "liquid|wet" for kIOLiquidDetectionEvent entries correlating with the 100% nights. A stuck eSIM modem reset (common on iPhone 16 baseband firmware 2.0.x) can also spike thermals past 42 °C, triggering the same override; verify with pmset -g thermlog | awk '/ThermalLevel/ && $NF >= 3'. Hardware recovery: force-restart (Vol+ Vol- Side) to clear the PMGR fault latch, then re-enable Optimized Battery Charging to reset the calibration schedule.

An iCloud Keychain/2FA re-key operation (triggered by Passkey rotation or Apple Account security audit) wakes the Secure Enclave for ~90 s every 14 days, pulling 1.2 W sustained; the PMGR treats this as “user-initiated activity” and temporarily lifts the 80% ceiling to guarantee boot-ready capacity. Correlate with log show --predicate 'subsystem == "com.apple.authd" or subsystem == "com.apple.cloudd"' --info | grep -E "keychain.rotate|passkey.sync|2fa.*challenge" — timestamps matching the 100% charges confirm the cause. No hardware fault; mitigate by scheduling “Require Face ID for Passkeys” off-peak or disabling automatic Keychain sync in Settings > Passwords > Password Options.