Ok I forgot to unplug my scan unit. I used to leave v1 in the car.
Ive had issues with near dead battery only recently and thought the battery was on the way out. Had to jump start today.
When getting out the car I noticed the v2 unit was still on full bore with backlight and everything, DUH! Now I remembered...
Moral of the story remember to unplug your v2 from the ODBII/CAN port else prepare for battery death.
BTW It took 2 weeks to get to that stage.