Please route this reproducible battery-status reporting issue to the Dell TechHub/Instrumentation and platform BIOS/EC/ACPI engineering teams.

SUMMARY

On my XPS 13 7390, a controlled replay of the battery-enumeration WMI sequence identified in the installed Dell component reproduced transient invalid battery reports. Five abnormal episodes occurred, including three actual 0%-charge episodes. Valid-index controls produced none.

SYSTEM

Dell XPS 13 7390, conventional laptop model
Windows 10 Pro, build 19045
BIOS 1.29.0
Dell TechHub 1.8.6
InstrumentationSubAgent / CommonPlatformServices 3.10.11.9482

The charger is connected directly. Two genuine batteries were previously replaced for the same symptom.

REPRODUCTION

DellTechHub was stopped, and its InstrumentationSubAgent process and helper were explicitly stopped and verified absent during the trial.

A separate script replayed the battery-enumeration sequence identified in the installed CommonPlatformServices component:

Namespace: ROOT\WMI
Class: DDVWmiMethodFunction
Input: arg2, UInt32
Methods: BatterySerialNumber and BatteryManufactureName

For each index in [1, 2, 3], the sequence reads BatterySerialNumber and, if the result is zero, BatteryManufactureName.

Only index 1 represents an installed battery on this system. Indices 2 and 3 return zero/empty results.

RESULTS

600 control calls using only index 1:
No abnormal episodes.

220 calls using the 1/2/3 enumeration sequence:
Three abnormal episodes, including two 0%-charge episodes.

240 calls using a 1/2 sequence:
One abnormal episode with a false 6% reading.

240 calls using a 1/3 sequence:
One 0%-charge episode.

Total: five abnormal episodes, three reaching 0% charge. All five included zero reported voltage and lasted approximately one second.

AC remained reported online. During each affected interval, EC-mediated telemetry reported approximately 7634-7636 mV and 54% charge. BIOS-mediated telemetry reported 53% charge.

The script issued the relevant WMI query sequence. It did not inject false readings or replay the entire Dell application.

TRACE FINDINGS

Each affected BAT0._BST evaluation overlapped Dell WMDV execution attributable to the replay client.

Inspection of this machine's ACPI tables showed that BAT0._BST, through ECG6, and WMDV use EC register 0x03 as a battery selector before reading battery data.

This is consistent with a shared-selector synchronization or unsupported-index handling defect. The exact internal interleaving has not been established.

SPONTANEOUS RECURRENCE

After DellTechHub was restored, another event occurred on October 3, 2026 at approximately 22:05:57 UTC+03:00.

Windows reported 52% -> 5% -> 52%. The replay script was no longer running. WMI tracing identified a concurrent BatterySerialNumber request from Dell.TechHub.Instrumentation.SubAgent.exe.

This was a false-low event, not an additional captured 0%-charge episode.

LIMITATIONS

This was a bounded experiment on one machine.

Additional diagnostic EC/BIOS pollers remained active throughout both control and treatment phases. Their contribution to timing is not excluded.

The voltage readings were software telemetry, not physical electrical measurements. No raw SMBus capture was performed.

The evidence establishes a reproducible reporting failure under these conditions. It does not establish an EC chip failure, exclude every hardware issue, or explain every previous sleep/shutdown.

CURRENT MITIGATION TEST

DellTechHub startup has now been disabled, and the service and instrumentation reader have been stopped. All deep diagnostic polling has also stopped.

Only basic Windows battery-percentage logging remains for a 48-hour observation period. This period is not yet complete, and a permanent fix has not been validated.

REQUESTED ENGINEERING REVIEW

Please investigate:

1. Enumeration of unsupported battery locations on this platform.
2. Synchronization of battery selection and subsequent status reads across WMDV and BAT0._BST.
3. Whether a known issue or software/BIOS fix addresses this behavior.
4. Reproduction with additional diagnostic pollers removed and on a second matching system.

The warranty-based chatbot does not provide a reporting route for this system.

I have a detailed engineering report, sanitized event summaries, reproduction logs, and original ETW traces. This forum form has no attachment option. Please provide a private upload channel and, if possible, an engineering tracking reference.

@DELL-Daniel V

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