I put fresh batteries in both keys a year ago when I bought the car (just a precaution) and all worked fine until about a month ago when things went awry. I get "key still in vehicle" when I am getting into the car and "key not detected" when I try to start it. No warning about the batteries being low. Best one is where I unlock the car, open the door and get a red "door open" warning. I just put fresh batteries in the key that had stopped working altogether (although it would lock and unlock the car) and it's working properly again. Is it usual for the key batteries to drain so quickly?