You may have been sweating a little and/or you had more salt intake thus saltier sweat. You may have acidified your body that day or over a period! Remember you would have full battery strength and believe me I notice a difference between 8 and 9v with my Terminator. Please don't rely on a Zapper you must utilise food, Water, Cleanses in your protocol for proper health otherwise your only playing with a small area and not getting to the root just like the Medical Mafia Cartel and their poxy drugs.