The INFINITI key fob functions on the CR2025 battery; however, a key fob that functions for the INFINITI Intelligent Key will need a CR2032 battery. Most car key fob batteries are not rechargeable, and the driver needs to replace it once it runs out of charge. As a driver, you will need to learn how to detect that your key fob is becoming weaker, and when it is on the verge of losing its transmitter range. Some cars will give you a warning message depicting that the key fob battery is running low. You need to follow some steps that allow you to replace the INFINITI key fob battery successfully.