Originally Posted by
pizzaguy
The battery in the FOB is for the transmitter that locks and unlocks the doors, and only that.
The RFID chip in the key is what enables engine start, but once the car is running, it's job is over.
Well, start the engine, remove the battery and make a trip. I have had a few stops of engine while driving the car from Connecticut to Florida. The reason is a key fob dead battery.. After replacing the battery in NJ the problem had gone. Still have no any issues.