Battery capacity/gauge instability after BIOS update to F.38RevA (HP 15s-eq2202nw) — downgrade block

[c0d1x123]

BIOS: F.38 RevA
OS: Windows 11 Home 25H2(26200.8655)

Issue description:
After updating the BIOS from F.34 to F.38RevA, my battery's reported full charge capacity and charge percentage became highly unstable. This did not happen before the update. Downgrading to F.34 is blocked by the system, and no newer BIOS version has been released in over 4 months to address this.

Evidence from the Windows battery report (powercfg /batteryreport):

1) Full charge capacity swings up and down within days, which is not physically possible for real battery wear:
- 2026-06-28: 23,389 mWh
- 2026-06-29: 24,357 mWh
- 2026-06-30: 22,453 mWh
- 2026-07-01: 24,008 mWh
- 2026-07-02: 23,893 mWh
- 2026-07-04: 24,239 mWh
- 2026-07-05: 23,982 mWh

2) Since the report began (2026-05-17), reported capacity dropped from 28,392 mWh to the ~23,000-24,000 mWh range within about 7 weeks - an implausibly fast and non-monotonic change for genuine cell degradation.

3) Battery life estimates at full charge are extremely low and inconsistent day to day, ranging from about 25 minutes to 1.5 hours, and as low as 3 minutes on some days - far below normal expected runtime for this model.

4) The event log also shows abrupt percentage/capacity drops within minutes while the system reports being on AC power, consistent with a battery gauge/firmware measurement fault rather than actual discharge.

Request:
Please investigate this as a firmware regression introduced in BIOS F.38RevA affecting battery gauge/reporting accuracy, and either:
(a) release a corrected BIOS update, or
(b) provide an official downgrade path back to F.34 or an earlier stable version

I have the full battery-report.html available and can attach it if needed.

Thank you.

[Hawks_Eye]

Hi @c0d1x123 

Welcome to the HP Support Community! We're here to help you get back up and running.

Thank you for providing the detailed battery report data and observations. I understand the concern, especially since the behavior appeared after updating from BIOS F.34 to F.38 Rev.A and was not present beforehand.

Based on the information shared, the reported Full Charge Capacity values are fluctuating significantly over short periods of time rather than following a gradual decline pattern. 

The variations between approximately 22,000 mWh and 24,000 mWh within days, together with inconsistent runtime estimates and abrupt percentage changes while connected to AC power, can indicate that the battery gauge data may not be aligning correctly with the actual battery state. 

Please notethat battery calibration can help reset the battery gauge so Windows displays charge and capacity information more accurately.

Before attributing the behavior solely to battery aging, HP recommends validating the battery through HP PC Hardware Diagnostics and performing a battery calibration, which is designed to resynchronize the battery gauge with the battery's actual charge state.

Please perform the following checks:

Run the HP Battery Test

• Power off the notebook.
• Turn it on and immediately tap Esc repeatedly.
• Press F2 for HP PC Hardware Diagnostics UEFI.
• Select:
  • Component Tests
  • Power
  • Battery
  • Run Once
• Record the result, including any Failure ID if displayed.

If offered, perform Battery Calibration

• From the Battery Test results screen, select Calibrate Battery.
• Allow the calibration process to complete fully. HP notes that calibration resets the battery gauge so charge levels are reported more accurately. [support.hp.com]

After calibration

• Generate a new battery report using: powercfg /batteryreport
• Compare Full Charge Capacity readings over several charge/discharge cycles rather than a single day. HP references the Windows battery report as a useful tool for evaluating battery capacity trends and cycle information.

Regarding the BIOS downgrade request, HP platforms can allow access to earlier BIOS revisions only when supported for the specific model and firmware configuration. Available previous BIOS versions are typically listed under the BIOS section of the product's driver page when rollback is supported.

Reference:

HP Notebook PCs - Testing and calibrating the battery (Windows) | HP® Support
 

Once the HP Battery Test result and calibration outcome are available, the data can be compared against the battery report history to determine whether the readings are being influenced by battery gauge calibration or by another firmware-related condition.

Take care, and have an amazing day!

Regards, 

Hawks_Eye