You will hear both sides of this story , I changed mine a month ago but I was wary about doing it as quick as possible some say that the battery needs to be replaced in x amount of seconds 30,20,10 you name it. The guy in the market I bought mine from agreed with the delay time of under 20secs. So did mine quickly and no problems. How ever I had a spare key ready just in case. I am sure others will have had a different experience.