Get low battery notifications for mouse earlier

Question

Is it possible to tweak the % that I get warning of low battery for my Magic Mouse 2?

I currently only get it at 2% at which point it's very close to dying so I have to stop what I'm doing and plug it in. A reminder about 10-15% would allow me to plug it in the next time I have a natural break.

Answer 1

For those willing to copy and run a bash script and add a cron job, here is a complete solution that is free and current (as of macOS Catalina 10.15.3) and requires no programming (I've done that part for you), just a little system administration:

Save this to a bash script like ~/.mouse-battery-check.sh:

#!/usr/bin/env bash
PATH=/usr/local/bin:/usr/local/sbin:~/bin:/usr/bin:/bin:/usr/sbin:/sbin

# current battery level
BATT=$(ioreg -c AppleDeviceManagementHIDEventService -r -l \
  | grep -i mouse -A 20 | grep BatteryPercent | cut -d= -f2 | cut -d' ' -f2)

# defaults to warn at 20%; accepts other number as 1st argument (useful for testing)
COMPARE=${1:-20}

if [ -z "$BATT" ]; then
  echo 'No mouse found.'
  exit 0
fi

if (( $BATT < $COMPARE )); then
  osascript -e "display notification \"Mouse battery is at ${BATT}%.\" with title \"🪫 Mouse Battery Low\""
fi

Open up Terminal and make the script executable:

chmod +x ~/.mouse-battery-check.sh

Now you can test that the script sends a desktop notification by running it when your BlueTooth mouse is connected (this tests for battery less than 101%, so it should always send a notification):

~/.mouse-battery-check.sh 101

To test again with the default setting (20%):

~/.mouse-battery-check.sh

When a BlueTooth mouse is not detected, the script will return, "No mouse found."

Checking Automatically

Now to test periodically and notify you automatically, add a new cron job:

env EDITOR=nano crontab -e

Add an entry like to check every 15 minutes:

*/15 * * * * cd ~ && bash ~/.mouse-battery-check.sh

(You can again pass the battery percentage as a parameter to the script here.)

Press Control+X then Y then Enter to exit the editor and save the cron job.

Compatibility

This has been tested on:

• Catalina 10.15.3
• Mojave 10.14.6
• High Sierra 10.13.x in June 2018

Acknowledgements

For battery check, this answer:

adjust battery-warning-level of magic mouse

For notification, this answer:

How can I trigger a Notification Center notification from an AppleScript or shell script?

For cron jobs, this blog:

https://ole.michelsen.dk/blog/schedule-jobs-with-crontab-on-mac-osx.html

User sirclesam for compatibility testing.

Enhancement - also check keyboard (and maybe trackpad)

I modified the script above to check both Apple Magic Mouse and Keyboard. With the addition of one word it could check Trackpads, or any other overpriced Apple Magic doo dads, as well. I only have the mouse and keyboard so I started with that. I also changed the default to 10% which still gives me a few days to plug it in. Trackpad does follow the same syntax.

#!/usr/bin/env bash
# Check battery level of Apple Magic Mouse and Keyboard and Notify if low

PATH=/usr/local/bin:/usr/local/sbin:~/bin:/usr/bin:/bin:/usr/sbin:/sbin

# Warn at 10% or according to first parameter.  Pass in 101 for testing.
COMPARE=${1:-10}

# Check each device.  
# If you have a Trackpad please add the suitable token to this list and test it.
for HIDThingy in Keyboard Mouse; do
    # Determine battery level of Apple Magic Thingy
    BATT=$(ioreg -c AppleDeviceManagementHIDEventService -r -l \
         | grep -i $HIDThingy -A 20 | grep BatteryPercent | sed -e 's/.* //')

    if [ -z "$BATT" ]; then
      echo "No $HIDThingy found."
    elif (( $BATT < $COMPARE )); then
      osascript -e "display notification \"$HIDThingy battery is at ${BATT}%.\" with title \"🪫 $HIDThingy Battery\""
    fi
done

Answer 2

There is a way!

Sadly you need BTT (Better Touch Tools) for this. BTT was free, but to support ongoing development there is now a pay-what-you-want license model starting at 5 USD. But afaik you can test it for free for some days.

How to set the notification:

1. Start BTT → Menu bar → Preferences → Basic Settings → Check "Launch BTT on startup"
2. Switch to Advanced settings (top left hand corner)
3. Go to Mouse settings (top right hand corner)
4. Under "General" at the bottom there is "Warn if battery level is lower than X %"
5. Check the option and set your level.

Answer 3

The answer was very helpful but did not work any more with the current macOS (Sonoma at the moment).

I decided to create a little app including a designed icon that notifies the user when the battery level of one of the Magic Mouse, Magic Keyboard or Magic Trackpad drops below a threshold value. The key features are:

Key features include:

• Supports monitoring multiple Apple devices simultaneously, ensuring that you are notified for all connected devices.
• Displays a warning notification if the battery of any device drops below 20%.
• Battery levels are checked automatically every 10 minutes.
• Notifications are displayed every 3 hours if the battery remains below 20%.

I called the app Magic Warning: https://github.com/alberti42/Magic-Warnings

On the GitHub page you find more detailed instructions how to install it. Here is the first release.

Answer 4

I wanted to share an update to Will's answer.

It appears that macOS Sequoia has removed the Product name when looking at the results for AppleDeviceManagementHIDEventService. I'm attempting to cross-reference the ProductID with results from system_profiler for Bluetooth devices.

#!/usr/bin/env bash
# Check battery level of Apple Magic Mouse and Keyboard and Notify if low

PATH=/usr/local/bin:/usr/local/sbin:~/bin:/usr/bin:/bin:/usr/sbin:/sbin

# Warn at 10% or according to first parameter. Pass in 101 for testing.
COMPARE=${1:-10}

# Arrays of names and their corresponding Product IDs
search_names=("Magic Keyboard" "Magic Mouse")
product_ids=()
product_names=()

# Get the Bluetooth devices information
bluetooth_info=$(system_profiler SPBluetoothDataType)

# Loop through each search name
for search_name in "${search_names[@]}"; do
    # Grep to find the relevant line and its context
    matching_device=$(echo "$bluetooth_info" | grep -A 5 "$search_name")

    # Check if a matching device was found
    if [ -z "$matching_device" ]; then
        echo "No device found matching: $search_name."
        continue
    fi

    # Extract the Product ID from the matching device
    product_id_hex=$(echo "$matching_device" | grep "Product ID" | awk '{print $3}')

    # Convert the hexadecimal Product ID to decimal
    product_id_decimal=$((product_id_hex))

    # add to the arrays (these must be of matching size just in case a search_names item is not found)
    product_ids+=("$product_id_decimal")
    product_names+=("$search_name")
done

# Iterate over the valid matches
for i in "${!product_ids[@]}"; do
    product_id="${product_ids[$i]}"
    device_name="${product_names[$i]}"

    # Determine battery level
    BATT=$(ioreg -c AppleDeviceManagementHIDEventService -r -l \
         | grep -i "\"ProductID\" = $product_id" -A 20 | grep BatteryPercent | awk '{print $3}')

    if [ -z "$BATT" ]; then
        echo "No $device_name found."
    elif (( BATT < COMPARE )); then
        osascript -e "display notification \"$device_name battery is at ${BATT}%.\" with title \"🪫 $device_name Battery\""
    fi
done

Answer 5

you can always download bitbar and just add some script to run, like this one https://github.com/kkunkel/OSX-Nagios.