Framework Battery Limit

A small Windows GUI for setting the battery charge limit on Framework laptops — without clicking through a UAC dialog every time, and without losing the value on the next reboot.

Why

Windows has no built-in charge limit setting; on every vendor it lives in firmware. Framework offers two ways in:

• BIOS (F2 → Advanced → Battery Charge Limit): permanent, but every change costs a reboot.
• framework_tool: sets the value in the embedded controller at runtime — but it's a CLI, it needs admin rights, and the value does not survive a reboot.

This project turns the second option into something you'd actually use day to day: a GUI with a slider, plus a scheduled task that restores your last setting after every logon. You get the convenience of the CLI and the persistence of the BIOS route.

What the GUI shows

• current charge limit and battery level, as a bar with a limit marker (orange = above the limit, discharging toward it)
• charge current, charge voltage and the resulting wattage — refreshed every 3 seconds, so you can watch the current ramp up and down live
• on battery: the live system power draw (discharge rate in W, plus current and voltage) and an estimated runtime remaining
• the charger's input current limit and LFCC (Last Full Charge Capacity — your battery health indicator over time)
• slider from 50–100 % plus 60/80/100 presets
• a checkbox to enable or disable the autostart task without opening Task Scheduler

Installation

Requirements: a Framework laptop, Windows, PowerShell 5.1 or newer.

git clone https://github.com/Strilled/framework-battery-limit.git
cd framework-battery-limit
# from an elevated PowerShell:
.\install.ps1

The script creates the target directory, downloads framework_tool.exe from its GitHub release, registers the tasks and creates the shortcuts.

Parameter	Default	Purpose
-InstallDir	%ProgramFiles%\FrameworkBatteryLimit	target directory
-Limit	80	initial limit in percent (ignored if limit.txt already exists)
-ToolVersion	v0.6.5	release tag of framework-system
-SkipDownload	–	don't download framework_tool.exe

Uninstall:

.\uninstall.ps1 -ResetLimit

How it works

Desktop shortcut
   └─ wscript fw-battery.vbs           ← not elevated, no UAC
        └─ schtasks /run FrameworkBatteryLimit-GUI
             └─ task (RunLevel Highest)
                  └─ fw-gui-run.vbs → powershell fw-battery.ps1   ← the GUI
                       ├─ framework_tool.exe --charge-limit <n>
                       └─ writes <n> to limit.txt

Logon (+15 s)
   └─ task FrameworkBatteryLimit-Apply (RunLevel Highest, hidden)
        └─ fw-apply.vbs → powershell fw-apply.ps1
             └─ reads limit.txt, applies it, logs to fw-apply.log

Routing through a scheduled task is the trick that avoids the UAC dialog: the task runs with highest privileges, and triggering a task does not itself require elevation.

The .vbs wrappers exist for exactly one reason — wscript starts PowerShell with window style 0, so no console window flashes up.

File	Role
src/fw-battery.ps1	the GUI (WinForms)
src/fw-apply.ps1	headless: reads limit.txt, applies the value, writes the log
src/fw-battery.vbs	shortcut target, triggers the GUI task
src/fw-gui-run.vbs	action of the GUI task
src/fw-apply.vbs	action of the apply task
install.ps1 / uninstall.ps1	setup and removal

At runtime the install directory also gains framework_tool.exe, limit.txt (the remembered value) and fw-apply.log.

Third-party component: framework_tool

All the actual hardware work is done by framework_tool, Framework's own utility. This project is only a wrapper around it — it does not talk to the embedded controller itself.

Upstream	https://github.com/FrameworkComputer/framework-system
Vendor	Framework Computer Inc.
License	BSD-3-Clause (LICENSE.md)
Pinned version	v0.6.5 (override with -ToolVersion)
Download URL	https://github.com/FrameworkComputer/framework-system/releases/download/<tag>/framework_tool.exe
Commands used	--charge-limit [<n>], --power

The binary is not vendored in this repository. install.ps1 fetches it from the official GitHub release at install time and runs Unblock-File on it; .gitignore keeps it out of version control. If you'd rather supply it yourself, drop it into the install directory and pass -SkipDownload.

Credit for the hard part — talking to the EC, decoding the charger registers, supporting the whole Framework lineup — belongs to Framework and the framework-system contributors.

Security note

A task running with highest privileges that launches a script from a writable directory is a privilege escalation path: whoever can replace the script file gets admin rights on your next click. Therefore:

• the default install directory is %ProgramFiles%, where the standard ACL already covers this;
• for a custom path outside protected directories, install.ps1 hardens the ACL itself: inheritance off, write access only for SYSTEM and Administrators, owner set to Administrators.

One deliberate trade-off remains: any local process can trigger the GUI task. All it can do is open the GUI — it cannot change the limit without interaction — which for a charge-limit utility seems acceptable. If you disagree, skip the tasks and run fw-battery.ps1 directly as administrator.

Known quirks

• 5 % float range. The EC maintains a range rather than a point value: 80 means roughly 75–80 % in practice. This is intentional, so the charger doesn't constantly top up at the threshold.
• The value lives in the EC, not in NVRAM. Hence the apply task. Note that the BIOS writes its own setting into the EC at every POST, so there is a window of a minute or two after each cold boot during which the BIOS value applies, until the task kicks in 15 s after logon. If you want it truly nailed down, set the BIOS value as well — that also covers the case where Windows doesn't come up at all.
• framework_tool.exe strictly requires admin rights. Without elevation Windows just reports "access denied" — the binary isn't broken, its manifest declares requireAdministrator.
• The battery is not actively discharged. If it sits above the new limit it simply stays there and only drifts down once you run on battery.

Tested with

Framework Laptop 13 (AMD Ryzen 7040 Series), BIOS 03.16, Windows 11 Pro 26200, framework_tool v0.6.5.

Other Framework models should work but are untested — framework_tool itself supports them.

License

MIT, see LICENSE. This covers the wrapper in this repository only; framework_tool.exe remains under Framework's own BSD-3-Clause license as noted above.