macOS app to set battery charge limit for Intel MacBooks
This app modifies a parameter called BCLM (presumably "Battery Charge Level Max") in the SMC which limits the charge of the battery to a set value. It also modifies a parameter called BFCL ("Battery Final Charge Level") which controls the MagSafe LED indicator light to display the correct status.
The source code can be viewed by opening src/Charge Limiter.scptd in Apple's Script Editor. It is written in Javascript Application Scripting (or JXA).
The companion smcutil binary (located under src/Charge Limiter.scptd/Contents/Resources) was copied from this repository. The source code for smcutil is also available there.
Download the latest version from the releases page.
The app is not code signed so Gatekeeper will tell you that the app cannot be opened. In order to bypass this warning, you need to right-click on the app and select "Open". You will have to do this twice in order to get the option to open the app.
If you wish to fully charge the battery again, set the charge limit to "100". The app itself does not install anything so if you do not need it anymore you can safely move it to the trash.
This app will automatically check and notify you for any updates when you run it.