Abstract: A system and method for determining whether a resistor in a battery circuit on an electric vehicle cannot be used as a resistive heater for heating a cooling fluid for cooling the vehicle battery, but can used as a pre-charge resistor for starting the vehicle. A temperature sensor is provided proximate the resistor within the cooling fluid. The method turns on the resistor before turning on a coolant pump and samples the temperature at sample intervals over a predetermined period of time. The method then calculates an integral or differential of the sampled temperatures and compares that value with a calibrated threshold. If the temperature value is not greater than the threshold, meaning that the temperature indicates no cooling fluid is present, the algorithm disables the resistor for heating purposes, but maintains operation of the resistor for pre-charge purposes.

Abstract: A system and method for determining whether a resistor in a battery circuit on an electric vehicle cannot be used as a resistive heater for heating a cooling fluid for cooling the vehicle battery, but can used as a pre-charge resistor for starting the vehicle. A temperature sensor is provided proximate the resistor within the cooling fluid. The method turns on the resistor before turning on a coolant pump and samples the temperature at sample intervals over a predetermined period of time. The method then calculates an integral or differential of the sampled temperatures and compares that value with a calibrated threshold. If the temperature value is not greater than the threshold, meaning that the temperature indicates no cooling fluid is present, the algorithm disables the resistor for heating purposes, but maintains operation of the resistor for pre-charge purposes.