set Cap to (do shell script "ioreg -w0 -l | grep ExternalChargeCapable")
tell Cap to set {wallPower} to {last word of paragraph 1}

if wallPower = "Yes" then
        return 0
else
        set Cap to (do shell script "ioreg -wO -l | grep Capacity")
        tell Cap to set {Available, Max} to {last word of paragraph 2, last word of paragraph 1}
        set Pct to round (100 * Available / Max)

        if Pct <= 4 then
                tell application "iTunes"
                        pause
                end tell
                set volume 100
                do shell script "say -v \"Zarvox\" \"LOW BATTERY\" "
                if Pct <= 3 then
                        beep 5
                        do shell script "say -v \"Zarvox\" \"PLUG ME IN NOW MOTHER FUCKER\""
                end if
        end if
end if