These batteries are commonly known as sleeping batteries and form part of Jaguar Land Rover’s wider security strategy to reduce vehicle theft. In particular, they are designed to protect against relay theft, which has become one of the most common ways modern keyless entry vehicles are stolen.

Sleeping batteries are specially designed key fob batteries that stop your car key from transmitting a signal when it is not being used.

Under normal circumstances, your key fob continues to send out a low level signal even when it is sitting at home on a table or key hook. Criminals can intercept this signal using relay devices, allowing them to unlock and start the vehicle without ever touching the original key.

Once a sleeping battery is fitted, the behaviour of the key changes. When the key remains still for a short period of time, the battery automatically disables the signal. This means no signal is being transmitted while the key is stationary. As soon as the key is picked up or moved, the battery instantly reactivates and the key works exactly as it should.

In simple terms, when your key is not moving at home, it goes into a sleep mode. This prevents thieves from capturing the signal and using relay theft methods.

Vehicle theft involving keyless entry systems increased significantly in recent years, prompting manufacturers to take action.

Jaguar Land Rover responded by rolling out software updates, security recall campaigns, and the distribution of sleeping batteries to customers. These measures have already had a noticeable impact, with theft rates for Jaguar and Land Rover vehicles dropping substantially.

It is worth noting that sleeping batteries offer the most protection when your keys are at home and not being handled.

If you are walking around with your key in your pocket or bag, the key remains active and continues to transmit a signal as normal. Extra care is still advised in busy areas such as shopping centres and public parking areas.

If you have received sleeping batteries and need assistance fitting them, our video guide section provides clear step by step instructions for different Jaguar and Land Rover key fob designs.

If you need a spare Jaguar or Land Rover key, or if you want a lost key removed from your vehicle system for added security, you are welcome to contact National Car Keys for assistance.