An electrically heated smoking system includes a secondary unit capable of receiving a smoking article having an aerosol-forming substrate. The secondary unit includes at least one heating element and an interface for connection to a primary power supply for supplying electrical power to the at least one heating element during a pre-heating mode, to increase the temperature of the aerosol-forming substrate to an operating temperature. The secondary unit further includes a secondary power supply arranged to supply electrical power to the at least one heating element during a smoking mode, to maintain the temperature of the aerosol-forming substrate at substantially the operating temperature. The secondary unit also includes secondary circuitry. The electrically heated smoking system optionally includes a primary unit.