This cable is for your SE7EN battery charger.  Plug this bad boy into the wall and then plug it into your charger and just like that you will have a charging battery.  Your charger should have come with one of these, so most likely this will be acting as a replacement due to some unfortunate circumstances.  Either way, it is here to save the day.
*This is not the charger itself.  It is just the cord for it.