Patent ID: 7956583

Claim:
Apparatus for warming a fluid, the apparatus comprising: a first conductive path from an external power source to a heater; a second conductive path from a battery to the heater; a third conductive path from the first conductive path to a charger, wherein the charger is coupled to the battery through a fourth conductive path, where at least one portion of the second conductive path is not common with the first, third and fourth conductive paths and the at least one portion is only used for discharge current to the heater; a first order battery protection circuit, coupled to at least one sensor and a battery disconnect switch located between the third and fourth conductive paths, for disconnecting the battery from the charger in response to a first predetermined condition; a second order battery protection circuit, coupled to the at least one sensor and a thermal fuse located between the first and second conductive paths, for opening the thermal fuse in response to a second predetermined condition; and a fluid warmer over temperature protection circuit, coupled to the thermal fuse, for opening the thermal fuse in response to excessive fluid temperature.