Hey Peter,
Sometimes searching the forum bears fruit.
When searching for battery power the first hit is Trigger macro When On/Off Battery Power.
Searching the wiki for battery returns this result.
So – there's a Keyboard Maestro function that returns 0 or 1 for the battery in-use status.
You can also use the shell:
How do I programatically detect if my laptop is plugged in or not? (osx)
The basic command:
pmset -g ps
Run it in the Terminal to see what it does – the output looks like this:
Now drawing from 'AC Power'
-InternalBattery-0 (id=4456547) 100%; charged; 0:00 remaining present: true
Here's how to use it as an effective test:
if [[ $(pmset -g ps | head -1) =~ "AC Power" ]]; then
echo "Power On"
else
echo "Power Off"
fi
-Chris