A server (16) arranged to automatically detect replacement of a vehicle battery (6) associated with a vehicle engine (5) comprises: a communications device (20) configured to receive vehicle battery voltage measurements from a telematics device (10) connected to or incorporating a voltage monitoring unit for the vehicle battery (6); and one or more processors (18) configured to process the vehicle battery voltage measurements. The processor(s) (18) monitor the voltage measurements in a first time window corresponding to an engine off state and assess when the voltage measurements in the first time window indicate a step change in voltage magnitude at a given time. The step change is then used to automatically identify a vehicle battery replacement event.