Vehicular communication device

A vehicular communication device communicable with an external communication device disposed outside a vehicle and at least one electronic control unit mounted in the vehicle, the vehicular communication device comprising:

• a processor with memory configured to:
• receive a write target data, which is to be written in at least one write target device among the at least one electronic control unit, from the external communication device;
• and
• transmit the write target data to the at least one write target device so as to write the write target data into the at least one write target device;
• wherein the processor calculates an estimated electric power amount as an estimated value of an electric power consumption in the vehicle, which is required for transmitting and writing the write target data from the external communication device into to the write target device via the vehicular communication device;
• obtains a battery remaining amount which is an electric power amount stored in a battery as a power supply source for supplying electric power to the at least one electronic control unit and the vehicular communication device;
• and
• determines whether the write data transfer is executed or suspended, based on an obtained battery remaining amount and the estimated electric power amount calculated by the processor, wherein the processor calculates the estimated electric power amount according to at least:
• a first communication speed between the external communication device and the vehicular communication device;
• a second communication speed between the write target device and the vehicular communication device;
• and
• electric power consumption of the write target device and the vehicular communication device.