[Bug 2173784] Re: ThinkPad T480: intermittent BAT1 capacity collapse (20.03 Wh to 4.98 Wh) after reboot with 7.0.0-43-generic

** Tags added: kernel-daily-bug -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2173784 Title: ThinkPad T480: intermittent BAT1 capacity collapse (20.03 Wh to 4.98 Wh) after reboot with 7.0.0-43-generic Status in linux package in Ubuntu: New Bug description: Ubuntu package: linux Suggested title: ThinkPad T480: intermittent BAT1 capacity collapse (20.03 Wh to 4.98 Wh) after reboot with 7.0.0-43-generic System: Lenovo ThinkPad T480, machine type 20L6SARA00 BIOS N24ET81W (1.56), EC N24HT37W Ubuntu/Kubuntu, x86_64 Battery BAT0: SMP 01AV421, internal, design capacity 24.00 Wh Battery BAT1: Celxpert 01AV424, removable, design capacity 24.05 Wh Charge thresholds for both batteries: start 76%, stop 80% Observed issue: On 2026-11-08 at 16:41 CET, BAT1 was discharging normally at 76% with energy_now=15.32 Wh and energy_full=20.03 Wh. After rebooting into 7.0.0-43-generic, a subsequent measurement at 16:53 showed BAT1 status=Not charging, capacity=0%, energy_now=0 Wh, energy_full=4.98 Wh, while BAT0 was discharging. The external battery did not provide power in that state. With AC connected, BAT1 was subsequently reported as Charging at approximately 3.994 W, but its reported energy_full remained 4.98 Wh at that time. On 2026-11-09, after running 7.0.0-42-generic, BAT1 again reported plausible capacity (energy_full=18.29 Wh, energy_now=14.58 Wh, 80%). The user observed BAT1 charging and discharging while using 7.0.0-42-generic. At 18:05 CET with AC disconnected, BAT0 was discharging at 7.876 W while BAT1 remained at 80% and 0 W. A second measurement 25 seconds later showed the same selection. At 18:12 CET after rebooting back into 7.0.0-43-generic without AC, BAT1 still reported energy_full=18.29 Wh, energy_now=14.58 Wh, capacity=80%, status=Not charging, power_now=0. BAT0 was discharging at 9.303 W. Thus the capacity collapse did NOT recur during this reboot. Both batteries were detected by ACPI, and thinkpad_acpi registered both charge thresholds without obvious errors in the filtered kernel log. Expected behavior: BAT1 should retain a consistent, plausible full-charge capacity across reboots and should be available to discharge when selected by the ThinkPad embedded controller. Actual behavior: Intermittent BAT1 capacity reporting collapse to 4.98 Wh/0% after a reboot into 7.0.0-43-generic, with the battery temporarily unavailable for discharge. The failure is not reproducible on every boot. The discharge order of BAT0/BAT1 is controlled by the embedded controller, so BAT1 reporting 0 W while BAT0 discharges is not by itself evidence of failure. Regression status: Possible regression between 7.0.0-42-generic and 7.0.0-43-generic; NOT conclusively established. Other factors, including EC/battery gauge state, may be involved. A later boot into 7.0.0-43-generic did not reproduce the capacity drop. Package history on 2026-11-09: OpenJDK 25 JRE, FreeRDP-related packages, and libnfs14 were updated. No kernel or obvious power-management package update was recorded on that date. Evidence logs: === VOR HERUNTERFAHREN === 2026-11-08T16:41:44+01:00 [BAT0] manufacturer=SMP model_name=01AV421 present=1 status=Not charging capacity=90 energy_now=17570000 energy_full=19630000 energy_full_design=24000000 cycle_count=122 [BAT1] manufacturer=Celxpert model_name=01AV424 present=1 status=Discharging capacity=76 energy_now=15320000 energy_full=20030000 energy_full_design=24050000 cycle_count=107 === NACH NEUSTART === 2026-11-08T16:53:11+01:00 2026-11-08 16:43:58 [BAT0] manufacturer=SMP model_name=01AV421 present=1 status=Discharging capacity=83 energy_now=16290000 energy_full=19630000 energy_full_design=24000000 cycle_count=122 [BAT1] manufacturer=Celxpert model_name=01AV424 present=1 status=Not charging capacity=0 energy_now=0 energy_full=4980000 energy_full_design=24050000 cycle_count=107 [AC] online=0 === NETZTEIL IM LAUFENDEN BETRIEB ANGESCHLOSSEN === 2026-11-08T16:56:19+01:00 [AC] online=1 [BAT0] status=Not charging capacity=80 energy_now=15800000 energy_full=19630000 energy_full_design=24000000 power_now=0 voltage_now=11931000 [BAT1] status=Charging capacity=0 energy_now=10000 energy_full=4980000 energy_full_design=24050000 power_now=3994000 voltage_now=12254000 ===== BASELINE BEFORE BOOTING NEW KERNEL ===== 2026-11-09T18:04:24+01:00 Linux T480 7.0.0-42-generic #42-Ubuntu SMP PREEMPT_DYNAMIC Thu Oct 15 08:06:44 UTC 2026 x86_64 GNU/Linux --- uptime --- 18:04:24 up 37 min, 1 user, load average: 0,46, 0,43, 0,30 --- power supplies --- [AC] online=1 [BAT0] manufacturer=SMP model_name=01AV421 serial_number= 4130 present=1 status=Not charging capacity=77 energy_now=16000000 energy_full=20710000 energy_full_design=24000000 power_now=0 voltage_now=12090000 cycle_count=123 charge_control_start_threshold=76 charge_control_end_threshold=80 [BAT1] manufacturer=Celxpert model_name=01AV424 serial_number= 2418 present=1 status=Not charging capacity=80 energy_now=14580000 energy_full=18290000 energy_full_design=24050000 power_now=0 voltage_now=12219000 cycle_count=108 charge_control_start_threshold=76 charge_control_end_threshold=80 --- installed kernel images --- /boot/vmlinuz-7.0.0-15-generic /boot/vmlinuz-7.0.0-22-generic /boot/vmlinuz-7.0.0-27-generic /boot/vmlinuz-7.0.0-28-generic /boot/vmlinuz-7.0.0-29-generic /boot/vmlinuz-7.0.0-30-generic /boot/vmlinuz-7.0.0-31-generic /boot/vmlinuz-7.0.0-34-generic /boot/vmlinuz-7.0.0-38-generic /boot/vmlinuz-7.0.0-42-generic /boot/vmlinuz-7.0.0-43-generic --- battery-related kernel log --- Nov 09 17:26:46 T480 kernel: ACPI: battery: Slot [BAT0] (battery present) Nov 09 17:26:46 T480 kernel: ACPI: battery: Slot [BAT1] (battery present) Nov 09 17:26:48 T480 kernel: thinkpad_acpi: ThinkPad ACPI Extras v0.26 Nov 09 17:26:48 T480 kernel: thinkpad_acpi: http://ibm-acpi.sf.net/ Nov 09 17:26:48 T480 kernel: thinkpad_acpi: ThinkPad BIOS N24ET81W (1.56 ), EC N24HT37W Nov 09 17:26:48 T480 kernel: thinkpad_acpi: Lenovo ThinkPad T480, model 20L6SARA00 Nov 09 17:26:48 T480 kernel: thinkpad_acpi: radio switch found; radios are enabled Nov 09 17:26:48 T480 kernel: thinkpad_acpi: This ThinkPad has standard ACPI backlight brightness control, supported by the ACPI video driver Nov 09 17:26:48 T480 kernel: thinkpad_acpi: Disabling thinkpad-acpi brightness events by default... Nov 09 17:26:48 T480 kernel: thinkpad_acpi: rfkill switch tpacpi_bluetooth_sw: radio is unblocked Nov 09 17:26:48 T480 kernel: thinkpad_acpi: battery 2 registered (start 76, stop 80, behaviours: 0xb) Nov 09 17:26:48 T480 kernel: thinkpad_acpi: battery 1 registered (start 76, stop 80, behaviours: 0xb) Nov 09 17:26:48 T480 kernel: ACPI: battery: new hook: ThinkPad Battery Extension Nov 09 17:26:48 T480 kernel: input: ThinkPad Extra Buttons as /devices/platform/thinkpad_acpi/input/input8 ===== END BASELINE ===== ===== AC DISCONNECTED: SAMPLE 1 ===== 2026-11-09T18:05:47+01:00 7.0.0-42-generic [AC] online=0 [BAT0] status=Discharging capacity=77 energy_now=15960000 energy_full=20710000 power_now=7876000 voltage_now=11686000 [BAT1] status=Not charging capacity=80 energy_now=14580000 energy_full=18290000 power_now=0 voltage_now=12214000 ===== AC DISCONNECTED: SAMPLE 2 (+25s) ===== 2026-11-09T18:06:12+01:00 7.0.0-42-generic [AC] online=0 [BAT0] status=Discharging capacity=77 energy_now=15890000 energy_full=20710000 power_now=8886000 voltage_now=11739000 [BAT1] status=Not charging capacity=80 energy_now=14580000 energy_full=18290000 power_now=0 voltage_now=12214000 ===== AFTER REBOOT: NEW KERNEL ===== 2026-11-09T18:12:27+01:00 Linux T480 7.0.0-43-generic #43-Ubuntu SMP PREEMPT_DYNAMIC Fri Oct 23 13:25:25 UTC 2026 x86_64 GNU/Linux 18:12:27 up 1 min, 1 user, load average: 1,43, 0,55, 0,20 [AC] online=0 [BAT0] manufacturer=SMP model_name=01AV421 serial_number= 4130 present=1 status=Discharging capacity=71 energy_now=14780000 energy_full=20710000 energy_full_design=24000000 power_now=9303000 voltage_now=11209000 cycle_count=123 charge_control_start_threshold=76 charge_control_end_threshold=80 [BAT1] manufacturer=Celxpert model_name=01AV424 serial_number= 2418 present=1 status=Not charging capacity=80 energy_now=14580000 energy_full=18290000 energy_full_design=24050000 power_now=0 voltage_now=12214000 cycle_count=108 charge_control_start_threshold=76 charge_control_end_threshold=80 --- relevant kernel messages --- Nov 09 18:10:38 T480 kernel: ACPI: battery: Slot [BAT1] (battery present) Nov 09 18:10:38 T480 kernel: ACPI: battery: Slot [BAT0] (battery present) Nov 09 18:10:39 T480 kernel: thinkpad_acpi: ThinkPad ACPI Extras v0.26 Nov 09 18:10:39 T480 kernel: thinkpad_acpi: http://ibm-acpi.sf.net/ Nov 09 18:10:39 T480 kernel: thinkpad_acpi: ThinkPad BIOS N24ET81W (1.56 ), EC N24HT37W Nov 09 18:10:39 T480 kernel: thinkpad_acpi: Lenovo ThinkPad T480, model 20L6SARA00 Nov 09 18:10:39 T480 kernel: thinkpad_acpi: radio switch found; radios are enabled Nov 09 18:10:39 T480 kernel: thinkpad_acpi: This ThinkPad has standard ACPI backlight brightness control, supported by the ACPI video driver Nov 09 18:10:39 T480 kernel: thinkpad_acpi: Disabling thinkpad-acpi brightness events by default... Nov 09 18:10:39 T480 kernel: thinkpad_acpi: rfkill switch tpacpi_bluetooth_sw: radio is unblocked Nov 09 18:10:39 T480 kernel: thinkpad_acpi: battery 1 registered (start 76, stop 80, behaviours: 0xb) Nov 09 18:10:39 T480 kernel: thinkpad_acpi: battery 2 registered (start 76, stop 80, behaviours: 0xb) Nov 09 18:10:39 T480 kernel: ACPI: battery: new hook: ThinkPad Battery Extension Nov 09 18:10:39 T480 kernel: input: ThinkPad Extra Buttons as /devices/platform/thinkpad_acpi/input/input6 ===== END AFTER REBOOT ===== ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-43-generic 7.0.0-43.43 ProcVersionSignature: Ubuntu 7.0.0-43.43-generic 7.0.14 Uname: Linux 7.0.0-43-generic x86_64 ApportVersion: 2.34.1-0ubuntu0.1 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: klaus 2637 F.... wireplumber /dev/snd/seq: klaus 2633 F.... pipewire CasperMD5CheckResult: unknown CurrentDesktop: KDE Date: Mon Nov 9 18:21:58 2026 InstallationDate: Installed on 2026-04-28 (195 days ago) InstallationMedia: Kubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423) MachineType: LENOVO 20L6SARA00 ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-7.0.0-43-generic root=UUID=c333d985-1c81-4f31-a2cc-67a7e1ffb212 ro rootflags=subvol=@ quiet splash PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 09/06/2025 dmi.bios.release: 1.56 dmi.bios.vendor: LENOVO dmi.bios.version: N24ET81W (1.56 ) dmi.board.asset.tag: Not Available dmi.board.name: 20L6SARA00 dmi.board.vendor: LENOVO dmi.board.version: SDK0J40697 WIN dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: None dmi.ec.firmware.release: 1.22 dmi.modalias: dmi:bvnLENOVO:bvrN24ET81W(1.56):bd09/06/2025:br1.56:efr1.22:svnLENOVO:pn20L6SARA00:pvrThinkPadT480:rvnLENOVO:rn20L6SARA00:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_20L6_BU_Think_FM_ThinkPadT480:pfaThinkPadT480: dmi.product.family: ThinkPad T480 dmi.product.name: 20L6SARA00 dmi.product.sku: LENOVO_MT_20L6_BU_Think_FM_ThinkPad T480 dmi.product.version: ThinkPad T480 dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2173784/+subscriptions