I happened to have chest pains this past Wed; morning. I have bilateral STN DBS and EKG's are unreadable without the stim being turned off. Well, the battery ( 9 volt) in my controller was dead. The ambulance didn't have one-I was away from home, in the car. Well, when we got to the ER they didn't have one either. Took 20 mins to get one so I could turn it off. All has worked out so far ok but geeeeeeeez.