Seems like a good idea for knowing when your battery is about to go out. I generally am within 1000' or less when flying so this might be a good idea for knowing when the batter is fading out over an onboard lipo alarm that you might not hear..
http://hobbyking.com/hobbyking/store/__ ... source=EDM
http://hobbyking.com/hobbyking/store/__ ... source=EDM