Abstract: A portable thermal device includes a housing having a thermally conductive container accessible through an opening. Batteries are contained in the housing. A power supply circuit is in electrical communication between an electrical heater and batteries contained in the to power the electrical heater. In one aspect, an electrical heater uses metal oxide semiconductor field effect transistors (MOSFETs) in thermal contact with the thermally conductive container that are driven in a heat generating range by the power supply circuit. In another aspect, a controller: (i) identifies a thermal profile associated for preparing and maintaining a particular food in the thermal conductive container; (ii) associates the thermal profile with stored power in the one or more batteries; and (iii) communicates via a user interface a limitation on performing the thermal profile based on the stored power.

Abstract: A portable thermal device includes a housing having a thermally conductive container accessible through an opening. Batteries are contained in the housing. A power supply circuit is in electrical communication between an electrical heater and batteries contained in the to power the electrical heater. In one aspect, an electrical heater uses metal oxide semiconductor field effect transistors (MOSFETs) in thermal contact with the thermally conductive container that are driven in a heat generating range by the power supply circuit. In another aspect, a controller: (i) identifies a thermal profile associated for preparing and maintaining a particular food in the thermal conductive container; (ii) associates the thermal profile with stored power in the one or more batteries; and (iii) communicates via a user interface a limitation on performing the thermal profile based on the stored power.