How to turn off Smart-Charging forever?

The Short Answer:

No, you cannot turn off Smart Charging permanently for good, nor can you customize the percentage threshold (to 90% or 95%).

Microsoft has hardcoded this safety mechanism deep inside the Surface UEFI firmware and the Surface Service background architecture. It is designed to automatically re-enable itself whenever it detects that the device is continuously plugged into a power source (or a dock) or running under elevated internal temperatures to prevent battery swelling.

Here is how the architecture works and the only workarounds available for your Surface Pro 9:

1. Why it keeps turning back on

Even if you manually unpause it, the Surface firmware overrides user settings. If your usage pattern involves keeping the Surface Pro 9 connected to the charger for days or prolonged hours, the embedded controller (EC) will automatically force Smart Charging back on to protect the hardware, capping it at 80%. There is no registry hack or group policy to change this behavior permanently.

2. The Only Way to Force 100% (Temporarily)

When you need full capacity for traveling, you must do it via the official app:

Open the Surface App.

Expand the Battery & charging section.

Click on Smart charging and select "Charge to 100%". Note: This will only stay active until your next prolonged plugging cycle, where the firmware will re-engage the 80% limit.

3. The UEFI Alternative (Battery Limit Mode - 50%)

If you hate the back-and-forth automated logic and your Surface is permanently docked on a desk, you can boot into the Surface UEFI (Hold Volume Up + Power Button during boot) and turn on Battery Limit Mode. This will hard-cap the battery at 50% strictly. This is the only other threshold Microsoft officially supports.

Modifying or attempting to delete the SurfaceService.exe or disabling the Surface Integration device driver in Device Manager to stop this feature is highly discouraged, as it will break screen auto-rotation, pen pressure sensitivity, and thermal regulation management.

Official Microsoft Support References for verification:

[1] Surface Smart Charging Behavior: For official documentation confirming that the feature automatically re-enables based on usage patterns, see "Smart charging on Surface" at support.microsoft.com.

[2] Surface UEFI Battery Configurations: For technical documentation regarding the 50% hard-cap limitation intended for continuous power scenarios, refer to "Battery Limit setting" under the Surface IT Pro deployment guides on Microsoft Learn.

Hi Yeoman

One additional detail, on supported Surface devices, selecting "Charge to 100%" in the Surface app is intended as a temporary override, not a permanent setting. Microsoft states that Smart Charging remains active on the device and may automatically re-enable when Surface determines it is needed based on charging patterns or battery conditions. At present, Microsoft does not provide a supported option to set a custom charging threshold such as 90% or 95%, nor is there a supported method to permanently disable Smart Charging.

If you'd like Microsoft to consider adding a permanent off switch or user-selectable charge limits (such as 90% or 95%), you can submit feedback directly:

Through the Surface app

1. Open the Surface app.
2. Select Settings.
3. Choose Give feedback.
4. Describe your request and submit it.

Through Feedback Hub

1. Press Win + F to open Feedback Hub.
2. Select Suggest a feature.
3. Search for existing feedback about Surface Smart Charging and upvote it, or create a new suggestion.
4. Include details such as a permanent disable option or custom charge thresholds (90%, 95%, etc.).

At present, Microsoft's documentation indicates that Smart Charging is designed to automatically re-enable when needed, and there is no supported option to permanently disable it or choose a custom charging percentage limit.