HP ZBook Fury 15 G7 random hard shutdowns – Kernel-Power 105/521, battery disappears

[Loevee]

Hello,

I am troubleshooting recurring hard power-offs on an HP ZBook Fury 15 G7 Mobile Workstation.

System

• HP ZBook Fury 15 G7
• Windows 11 Pro 25H2
• BIOS: S92 Ver. 01.25.00, 12 June 2026
• 32 GB RAM
• Intel Core i7-10850H
• NVIDIA Quadro T1000 with Max-Q

Main symptom

The laptop randomly powers off instantly while running normal Windows. There is no BSOD or shutdown screen. Event Viewer later records Kernel-Power Event 41 with no bugcheck.

Sometimes after such a shutdown the laptop will not boot normally until I hold the power button for approximately 30 seconds.

At the beginning of the problem I also had one incident where the laptop powered on with fans/lights active but no display, including external display. Caps Lock/Num Lock blinked approximately five times repeatedly. Using the HP Win+B BIOS recovery procedure allowed the laptop to boot again.

Very important: Safe Mode is stable

During the first occurrence of the problem, Windows Safe Mode ran continuously for approximately 6 hours without shutting down, while normal Windows could shut down within seconds or minutes.

HP UEFI diagnostics

I ran HP PC Hardware Diagnostics UEFI:

• System Board: PASS
• Memory: PASS
• Processor: PASS
• CPU stress test (~15 minutes): PASS
• Onboard video: PASS
• AC adapter: PASS
• USB/audio/PCI tests: PASS

The laptop can also remain running inside UEFI diagnostics for a long time without shutting down.

Battery test reports Primary Battery OK / Logic State OK, but Component Test WARNING. Battery has approximately 390 cycles and approximately 69% remaining full-charge capacity.

Windows troubleshooting already performed

I tested:

• clean boot with non-Microsoft services disabled
• startup applications disabled
• NVIDIA GPU disabled
• Intel Wi-Fi disabled
• VPN/Wintun/TAP adapters disabled
• Hyper-V temporarily disabled
• SFC /scannow: no integrity violations
• System Restore
• uninstalling Windows updates

None of these solved the issue.

I then performed Reset this PC → Keep my files → Cloud download.

After the fresh Windows installation, the laptop was completely stable for approximately one week, including WSL2 and Docker Desktop. Then the same hard shutdown problem returned.

Power-related Event Viewer data

While the original HP AC adapter remains physically connected and is not touched, Windows repeatedly records:

Kernel-Power Event 105 – Power source change

Example:

17:45:16 AcOnline=false

17:45:38 AcOnline=true

17:46:50 AcOnline=false

17:47:04 AcOnline=true

17:48:01 AcOnline=false

17:48:15 AcOnline=true

At exactly the same timestamps, Windows records:

Kernel-Power Event 521 – Active battery count change

with:

ValidBatteryCount=0

immediately followed by:

ValidBatteryCount=1

ErrorBatteryCount=0

AbandonedBatteryCount=0

So the Windows power subsystem appears to temporarily lose the battery at the same time that it reports AC power disappearing.

Windows Update

The PC was running Windows 11 25H2 build 26200.9168 with KB5121003.

I uninstalled KB5121003 and verified that it is no longer installed. The build reverted to 26200.8973 and Windows Update is currently paused.

However, the laptop performed another identical hard shutdown approximately 30 minutes later, so KB5121003 does not appear to be the sole cause.

Current test

I am currently testing the laptop completely disconnected from AC power, running only from the internal battery.

My main questions are:

1. Is this combination of Kernel-Power Event 105 (AcOnline false/true) and Event 521 (ValidBatteryCount 0/1) known on the HP ZBook Fury 15 G7?
2. Could this indicate an EC/ACPI/BMS/power-management issue rather than a simple battery failure?
3. Is BIOS S92 01.25.00 the recommended BIOS for this model?
4. Are there specific HP SoftPaq power-management / Intel Management Engine / ACPI drivers that should be installed or rolled back?
5. Considering that Safe Mode remains stable and HP UEFI diagnostics pass, what would be the recommended next diagnostic step?

Thank you.

[Loevee]

Battery-only normal Windows remained stable for several hours.
Safe Mode with the AC adapter connected also remained stable for approximately one hour.
The hard shutdowns currently reproduce only in normal Windows while AC power is connected.

[Deep_World]

Hi  @Loevee 
 
Welcome to the HP Support Community!

Thanks for reaching out!

Thank you for providing such a detailed description of the issue and the extensive troubleshooting you've already completed. I appreciate the time you've put in isolating the behaviour.

Based on the information you've shared, suggest a power-management communication issue that could involve the battery, embedded controller (EC), system board power circuitry, firmware, or related drivers. The fact that the system remains stable in Safe Mode and during HP UEFI Diagnostics adds valuable information to the review.

To better assist you, could you kindly confirm:

• Is the battery original HP battery or has it been replaced previously?
• Does the issue occur with any specific workload, or can it happen while the system is idle?
• Are you using the original HP Adapter supplied with the workstation?

In the meantime, kindly try the below steps and confirm :  

1. Perform an hard Reset - click here for steps 

1. Shut down the workstation.
2. Disconnect the AC adapter.
3. Hold the power button for 30 seconds.
4. Reconnect AC power and start the system.

2. Run HP Hardware Diagnostics Extensive Tests - Click here for steps

If not already performed, kindly run:

• Extensive System Board Test
• Extensive Battery Test
• Extensive Power Component Test

from HP PC Hardware Diagnostics UEFI.

Considering the symptoms you've documented, especially the simultaneous loss of AC and battery detection events, collecting the above information will help determine whether we're dealing with a battery communication issue, firmware/EC behavior, power delivery circuitry, or a software component interacting with the power subsystem.

I hope this helps. 

[Loevee]

Hi,

Thank you for the detailed response. I have continued testing and now have a much more specific reproduction of the issue.

To answer your questions:

• Battery: The battery is the original HP battery and has never been replaced.
• AC adapter: I am using the original HP AC adapter supplied with the workstation.]
• Workload: The shutdown does not require any specific heavy workload. It has occurred during light use and can also happen when the machine is essentially idle.

I have already performed the 30-second hard reset several times. In fact, after some of the hard shutdowns, the workstation would not boot normally until I disconnected AC power and performed the 30-second power-button reset.

I have also previously run several HP UEFI diagnostics:

• System Board Test — Passed
• AC Adapter Test — Passed
• Processor Test — Passed
• CPU Stress Test (~15 minutes) — Passed
• Memory Test — Passed
• Battery test — battery was detected and operational, although the battery is aged

The system can remain stable for long periods in HP UEFI Diagnostics.

I will additionally run the Extensive System Board Test, Extensive Battery Test and Extensive Power Component Test as you requested and report the results.

Important behaviour difference

I have been able to isolate a very clear difference depending on the operating mode:

• Normal Windows + AC connected: hard shutdowns occur.
• Normal Windows on battery only: the workstation has remained stable for several hours.
• Safe Mode + AC connected: the workstation has remained stable.
• HP UEFI Diagnostics are also stable.

This is why I suspect that the issue may be related specifically to the transition between battery and AC power, or to an interaction between Windows power management and the EC / charging circuitry.

New reproducible event

On 28 August 2026 at approximately 18:16, the workstation was running normally on battery.

Battery charge was approximately 64%. There was no significant thermal or GPU load immediately before the failure. Shortly before the event, the NVIDIA GPU was approximately:

• 54°C
• P8 power state
• approximately 4.7 W

I then connected the AC adapter while Windows was running.

The workstation powered off immediately at the exact moment the AC adapter was connected.

Event Viewer recorded the following events at exactly 18:16:44:

Kernel-Power Event 105
AcOnline = false

and simultaneously:

Kernel-Power Event 521
ValidBatteryCount = 0

Kernel-Power Event 521
ValidBatteryCount = 1

ErrorBatteryCount and AbandonedBatteryCount were both 0.

There was no subsequent AcOnline = true event before the workstation powered off.

This appears to show the following sequence:

Battery operating normally → AC adapter connected → battery temporarily disappears from the ACPI power subsystem → power-source transition begins → immediate hard power-off.

I have also seen repeated Event 105 / Event 521 pairs previously while the AC adapter was physically connected and had not been touched. In those cases Windows would temporarily report:

AcOnline = false → true
ValidBatteryCount = 0 → 1

HP Image Assistant test

I also ran HP Image Assistant.

HPIA reported that the combination of this ZBook Fury 15 G7 and Windows 11 25H2 is not currently supported by an HP reference image, so it used a generic OS reference.

HPIA recommended System Default Settings (SP151431). I installed only this package because it restores HP power-management defaults.

After installing SP151431, the workstation initially remained stable for approximately 4 hours while connected to AC, with no unexpected Event 105/521 activity.

However, the problem was not permanently resolved. The hard shutdown later reproduced again, and the most recent reproduction occurred exactly when connecting the AC adapter as described above.

Other troubleshooting already performed

For completeness:

• Windows was completely reset using Reset this PC → Keep my files → Cloud download.
• After the reset, the workstation was stable for approximately one week before the issue returned.
• NVIDIA graphics was previously disabled as a test; the issue still occurred.
• Intel Wi-Fi was disabled as a test; the issue still occurred.
• VPN/TAP/Wintun adapters were disabled; the issue still occurred.
• A clean boot with non-Microsoft services disabled did not resolve it.
• Hyper-V / virtualization was disabled as a test; the issue still occurred.
• SFC found no integrity violations.
• The relevant Windows cumulative update was uninstalled as a test, but the shutdown still occurred afterward.

There is no BSOD. Kernel-Power Event 41 shows BugcheckCode = 0; the system simply loses power.

Given the very specific battery-to-AC reproduction and the simultaneous Event 105 / 521 activity, could you please advise whether this behaviour is consistent with a problem involving:

• the AC adapter identification / power negotiation,
• battery communication,
• the embedded controller (EC),
• DC-in / charging circuitry,
• power-path switching circuitry,
• or the system board?

Would testing with another known-good original HP AC adapter of the correct wattage be the recommended next hardware isolation step?

I will also complete the requested extensive UEFI tests and post the results.

Thank you.

[Deep_World]

Hi @Loevee,

Thank you for taking the time to provide such a comprehensive update and for performing the extensive testing and isolation steps. I truly appreciate the level of detail you've shared, especially the reproducible behaviour you've identified when connecting the AC adapter while the system is running.

The information you've provided is valuable. Based on your findings, particularly the immediate shutdown occurring at the exact moment AC power is connected, along with the simultaneous Kernel-Power Event 105 (AcOnline = false) and Event 521 (ValidBatteryCount transitions) entries, it does indicate that the issue may be related to the system's power-management path rather than a conventional thermal, processor, memory, or operating system stability problem.

The fact that the workstation remains stable:

• On battery power alone
• In Safe Mode while connected to AC
• During HP Diagnostics

while the shutdown can be triggered during an AC power transition in normal Windows operation provides important for further isolation.

As a next isolation step, testing with another known-good genuine HP AC adapter of the correct wattage and specifications would be highly recommended, if one is available. This can help determine whether the issue is related to adapter identification, power delivery, or charging-path behaviour during AC connection events.

Additionally, kindly complete the:

• Extensive System Board Test
• Extensive Battery Test
• Extensive Power Component Test

from HP PC Hardware Diagnostics UEFI and share the results with us. Those results will provide further insight and help determine the most appropriate next course of action.