A mobile X-ray apparatus comprising: an X-ray radiator; a controller configured to control the X-ray radiator; and a power supply comprising a lithium ion battery comprising battery cells, the power supply being configured to supply an operating power to the X-ray radiator and the controller, a battery management system, "BMS", configured to control an operation of a protection circuit for protecting the lithium ion battery, and the protection circuit configured to protect the lithium ion battery against at least one of over-discharge, overcurrent, overheating, and unbalancing between battery cells; wherein the battery management system is configured to operate the protection circuit depending on at least one respective reference value for operating the protection circuit protecting against the at least one of over-discharge, overcurrent, overheating, and unbalancing between battery cells; wherein the battery management system is characterized in that it is further configured to: receive an X-ray emission preparation signal indicating that the X-ray radiator is prepared to start X-ray emission from the controller; change the at least one reference value based on the received X-ray emission preparation signal to prevent the protection circuit from operating protection against at least one of over-discharge, overcurrent, overheating, and unbalancing between battery cells; receive an X-ray emission completion signal indicating the completion of X-ray emission from the controller; change the at least one reference value back to the same value as before based on the received X-ray emission completion signal. an X-ray radiator; a controller configured to control the X-ray radiator; and a power supply comprising a lithium ion battery comprising battery cells, the power supply being configured to supply an operating power to the X-ray radiator and the controller, a battery management system, "BMS", configured to control an operation of a protection circuit for protecting the lithium ion battery, and the protection circuit configured to protect the lithium ion battery against at least one of over-discharge, overcurrent, overheating, and unbalancing between battery cells; wherein the battery management system is configured to operate the protection circuit depending on at least one respective reference value for operating the protection circuit protecting against the at least one of over-discharge, overcurrent, overheating, and unbalancing between battery cells; wherein the battery management system is characterized in that it is further configured to: receive an X-ray emission preparation signal indicating that the X-ray radiator is prepared to start X-ray emission from the controller; change the at least one reference value based on the received X-ray emission preparation signal to prevent the protection circuit from operating protection against at least one of over-discharge, overcurrent, overheating, and unbalancing between battery cells; receive an X-ray emission completion signal indicating the completion of X-ray emission from the controller; change the at least one reference value back to the same value as before based on the received X-ray emission completion signal. receive an X-ray emission preparation signal indicating that the X-ray radiator is prepared to start X-ray emission from the controller; change the at least one reference value based on the received X-ray emission preparation signal to prevent the protection circuit from operating protection against at least one of over-discharge, overcurrent, overheating, and unbalancing between battery cells; receive an X-ray emission completion signal indicating the completion of X-ray emission from the controller; change the at least one reference value back to the same value as before based on the received X-ray emission completion signal.