Can I use Applescript or Automator to automatically eject my external drive before the battery dies?

Question

Whenever I leave my macbook unplugged with my external hard-drive plugged in and the battery power runs out, my computer "dies" and my external hard-drive is not ejected properly, sending me a warning that data may be lost if not ejected properly. This has happened on several occasions.
Is it possible to program my external hard-drive to eject itself when my computer is running low on battery power so I do not have to worry about losing data from being ejected misproperly?
My system specs:
  Model Name:          MacBook
  Model Identifier:          MacBook1,1
  Processor Name:          Intel Core Duo
  Processor Speed:          2 GHz
  Number Of Processors:          1
  Total Number Of Cores:          2
  L2 Cache:          2 MB
  Memory:          2 GB
  Bus Speed:          667 MHz
  Boot ROM Version:          MB11.0061.B03
  SMC Version (system):          1.4f12
  Sudden Motion Sensor:
  State:          Enabled
I'm using a WD Passport 250 GB notebook external hard-drive.
Note: I use my external for time machine as well as for storing my entire iTunes library to free space on my macbook.

Answer 1

Alright, after trying stuff for some irritating hours, I think I've got something you can use. I haven't figured out how to get it to run all the time.
(I must be an idiot becuase I can't find where to upload this file)
Automator application
Run Shell Script (ignore this actions input)
ioreg -n AppleSmartBattery -r | awk '$1~/Capacity/{c[$1]=$3} END{OFMT="%.2f%"; max=c["\"MaxCapacity\""]; print (max>0? 100*c["\"CurrentCapacity\""]/max: "?")}'
Set Value of Variable
Variable: new variable... (I called it Battery Life)
Run AppleScript
on run {input, parameters}
          if input is less than "3.00" then tell application "Finder" to eject (every disk whose ejectable is true and local volume is true)
          return input
end run