REPRODUCIBILITY: Happened once so far, will update if it recurs
OS VERSION: 5.2.0.15 (issue occurred on this version; updated to 5.2.0.16 afterwards, not yet re-tested with a new charge cycle on .16)
HARDWARE: Jolla Phone (2026)
UI LANGUAGE: German
REGRESSION: unsure
DESCRIPTION:
The battery percentage shown in the UI appears to get stuck far below the actual charge level after charging overnight and switching between chargers. Checking the raw battery values (voltage, and internal state-of-charge estimates in the system log) showed the phone was actually much more charged than the displayed percentage indicated.
PRECONDITIONS:
- Charge limit set to 90% in Battery Manager
- Phone charged overnight, then charger switched at least twice during/after charging
STEPS TO REPRODUCE:
- Charge the phone overnight with the 90% charge limit enabled (indicator showed 17% in the morning)
- Switch to a different charger — indicator rose to 22%, then stopped increasing
- Switch to a third charger (genuine HP EliteBook laptop power supply) — indicator stayed at 22%, did not increase further
- Use the phone normally for several hours — indicator decreased only slightly (22% → 15% over ~13 hours), much less than expected for normal usage
EXPECTED RESULT:
The battery percentage should reflect the actual state of charge of the battery.
ACTUAL RESULT:
The battery percentage was stuck at a value far below the actual charge level. Checking /sys/class/power_supply/battery/uevent while the indicator showed 15% gave:
POWER_SUPPLY_CAPACITY=15
POWER_SUPPLY_VOLTAGE_NOW=4078000 (4.078 V)
POWER_SUPPLY_STATUS=Discharging
POWER_SUPPLY_CYCLE_COUNT=6
4.078V is quite high for a Li-ion cell — that’s a voltage you’d normally see at a much higher charge level, not at 15%.
Looking at the system log (journalctl -b), the battery driver internally tracks a couple of different state-of-charge estimates, and in my case they disagreed a lot with what was actually shown on screen:
soc:6653 fg_c_soc:6653 fg_v_soc:6576 ui_soc:1494 vc_diff:77
Two independent internal estimates (fg_c_soc, fg_v_soc) agreed the battery was at roughly 66%, while the value actually shown in the UI (ui_soc) was stuck at 15% — a discrepancy of about 50 percentage points.
MODIFICATIONS:
None relevant to this issue. Device has Developer Mode enabled and some OpenRepos/Chum packages installed, none related to power management.
ADDITIONAL INFORMATION:
Related threads I found while searching (none seem to be exactly the same issue, but may be connected):
- Erratic battery behaviour on C2 — different symptoms (rapid drain below 40-60%), but one reply mentions poor battery percentage calibration on C2 as well.
- Problem with the battery charge indicator on Sony Xperia 10 V — indicator also gets “stuck”, but tied there to a known Xperia 10V binary blob issue, so likely a different root cause.
- [5.2][Jolla Phone 2026] Phone reports that is charging upon Bluetooth controller connecting — different mechanism (false charging status via BT controller), but same device/OS version, so possibly worth cross-referencing for anyone investigating the charging subsystem on this device.
Happy to share more logs if useful, and will update this report if the issue recurs or if a full charge/discharge cycle resolves it.
