My Razr has started showing EV where it use to show Digital. The lady at the store says it is a high speed tower not to worry. Yesterday when it started I had just charged the battery. I used it for about 25 minutes of calls and then on standby. By 6 pm it was blinking low battery and then died. Does this ev signal use battery life much faster?. She said it is only on the Razr and the e815. Can I shut it off some way?