Your MacBook battery is dying while it sits on your desk.

Homebrew is a free tool that makes it easy to install software on your Mac. You might already have it. Let's check — paste this into Terminal:

brew --version

If you see a version number (like Homebrew 4.x.x), you're good — skip to Step 2.

If you see "command not found," install Homebrew by pasting this:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

batt is a free, open-source tool that controls your MacBook's charging. It's lightweight, has no ads or telemetry, and runs quietly in the background. Over 1,500 people use it on GitHub.

Install it:

brew install batt

Then start the background service that keeps it running (including after restarts):

sudo brew services start batt

What success looks like: You should see a message like ==> Successfully started batt.

Now tell batt to cap your battery. The most common choices are 70% or 80%:

• 70% — Best for longevity. Great if your Mac rarely leaves the desk.
• 80% — Good balance between longevity and having more charge when you unplug.

Pick one and paste the command. Here's 70%:

batt limit 70

Or for 80%:

batt limit 80

Verify it's working:

batt status

What success looks like: You'll see output including Upper limit: 70% (or whatever you chose). Your Mac will stop charging once it reaches that level.

Apple has its own battery management feature that conflicts with batt. You need to turn it off so the two don't fight each other.

This creates a small script on your Mac that flips between your desk limit and 100%. You'll use it whenever you need to go mobile (or come back).

If you chose 70% as your limit, paste this entire block:

mkdir -p ~/bin && cat > ~/bin/toggle-battery-limit.sh << 'SCRIPT'
#!/bin/zsh
CURRENT=$(/opt/homebrew/bin/batt status 2>&1)
if echo "$CURRENT" | grep -q "Upper limit: 70%"; then
    /opt/homebrew/bin/batt limit 100 2>&1
    osascript -e 'display notification "Charging to 100% — Mobile Mode" with title "🔋 Battery"'
else
    /opt/homebrew/bin/batt limit 70 2>&1
    osascript -e 'display notification "Capped at 70% — Desk Mode" with title "🔋 Battery"'
fi
SCRIPT
chmod +x ~/bin/toggle-battery-limit.sh

If you chose 80%, paste this version instead:

mkdir -p ~/bin && cat > ~/bin/toggle-battery-limit.sh << 'SCRIPT'
#!/bin/zsh
CURRENT=$(/opt/homebrew/bin/batt status 2>&1)
if echo "$CURRENT" | grep -q "Upper limit: 80%"; then
    /opt/homebrew/bin/batt limit 100 2>&1
    osascript -e 'display notification "Charging to 100% — Mobile Mode" with title "🔋 Battery"'
else
    /opt/homebrew/bin/batt limit 80 2>&1
    osascript -e 'display notification "Capped at 80% — Desk Mode" with title "🔋 Battery"'
fi
SCRIPT
chmod +x ~/bin/toggle-battery-limit.sh

What success looks like: No output means it worked. The script is saved and ready to use.

Now let's make it so you can toggle with a single tap from your menu bar — no Terminal needed day-to-day.

First, find your username. Paste this in Terminal and note the result:

whoami

Now open the Shortcuts app (search for it in Spotlight with Cmd + Space) and follow these steps:

1. Click "Menu Bar" in the left sidebar. Creating a shortcut here automatically pins it to your menu bar.
2. Click the + button to create a new shortcut.
3. In the search panel on the right, search for "Run Shell Script" and add it.
4. Set the Shell to zsh.
5. In the script body, type: /Users/USERNAME/bin/toggle-battery-limit.sh
   Replace USERNAME with the result from whoami above.
6. Make sure "Run as Administrator" is unchecked.
7. Rename the shortcut to "Toggle Battery Limit" (click the name at the top).

What success looks like: You now have a "Toggle Battery Limit" shortcut in your menu bar. Click the Shortcuts icon in the menu bar and you'll see it listed.

For even quicker access, you can add your shortcut to Control Center:

1. Open Control Center (click the icon in your menu bar).
2. Click the + at the bottom left.
3. Find and add Shortcuts.
4. Select "Toggle Battery Limit".

Now you can toggle your battery limit from Control Center with a single tap.