Device to indicate need to service or inspect a motor vehicle

A device for indicating the need for service or inspection of a motor vehicle because of the passage of a prespecified mileage since the device was zeroed, comprising:

• A. a signal transmitter (6) for producing an electrical signal proportional to the actual speed of the motor vehicle,
• B. an electrochemical ampere-hour sensor means (2, 9 or 13) connected to receive said signal and to integrate the amplitude of the signal over a time period, whereby the integrated signal provides a measure of the miles travelled by the vehicle, and
• C. means connected with the sensor for supplying a signal to an operator of the motor vehicle when the integrated signal reaches a prespecified value.