1. Continuous Signal Transmission: Keyless fobs use radio frequency (RF) technology to communicate with the car's immobilizer system. When the fob is inside the vehicle, it continuously transmits a signal to the immobilizer to keep the car unlocked and ready to start. This constant transmission can draw power from the car's battery, even when the car is turned off.
2. Passive Entry and Start (PEPS) System: Many modern vehicles are equipped with PEPS systems that allow keyless entry and starting. These systems use sensors to detect the presence of the key fob inside the vehicle and automatically unlock the doors and enable engine starting without the need to press a button. The sensors require power to operate, and if the key fob is left in the car, it keeps these sensors active, consuming battery power.
3. Low Battery Indicator: If the key fob's battery is low, some vehicles might activate an indicator light or chime to alert the driver. This feature can also drain the car's battery if the fob is left inside the vehicle for an extended period.
However, the amount of battery drain caused by a keyless fob will depend on factors like the car model, the key fob design, and the overall condition of the battery. In some cases, leaving the fob in the car for a short time might not have a noticeable impact on the battery, but over time, continuous power draw can lead to a drained battery.
To prevent battery drain, it's generally advisable to remove the keyless fob from the vehicle and take it with you when leaving the car for an extended period. Some car manufacturers also recommend storing the key fob away from the vehicle when not in use to avoid unintended signal transmissions.
