Electronic vapor provision system

A cartridge for use in an electronic vapor provision device, the cartridge comprising:

• a first electrical resistive heater having a first thermal coefficient of resistance;
• a second electrical resistive heater having a second thermal coefficient of resistance that is at least two times larger than the first thermal coefficient of resistance;
• a wick for transporting e-liquid from a reservoir to the first electrical resistive heater and the second electrical resistive heater;
• and
• a connection for electrically connecting the cartridge to a control system configured to monitor for a change in resistance of the second electrical resistive heater,
• wherein the first electrical resistive heater and the second electrical resistive heater are each mounted around the wick.

A method of operating an electronic vapor provision device, comprising:

• transporting e-liquid from a reservoir to a wick;
• vaporizing a precursor material using the first electrical resistive heater mounted on the wick to generate vapor in an airflow for inhalation by a user;
• vaporizing the precursor material using the second electrical resistive heater mounted on the wick to generate vapor in an airflow for inhalation by a user, wherein the second electrical resistive heater has a second thermal coefficient of resistance that is at least two times larger than a first thermal coefficient of resistance of the first electrical resistive heater;
• and
• monitoring, by a control system, for a change in resistance of the second electrical resistive heater.