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.app in Apple's Script Editor. It is written in Javascript Application Scripting (or JXA).
The companion bclm binary (located under src/Charge Limiter.app/Contents/Resources) was copied from this repository. The source code for bclm is also available there.
Download the latest version from the releases page.
When trying to open the app for the first time, Gatekeeper will prevent you from doing so because the app is not code signed. 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.
After setting a charge limit, the app will silently run and reapply the desired charge level again if you restart your Mac. If you wish to fully charge the battery again, set the charge limit to "100". This will also remove the charge limit persistency on boot. Afterwards, if you do not need the app anymore you can safely move it to the trash.
If you are running macOS High Sierra (10.13) or older, you may need to install Swift 5 Runtime Support.
This app will automatically check and notify you for any updates when you run it.