Lithium battery fire extinguishing system, underwater device and lithium battery fire extinguishing method

The invention provides a lithium battery fire extinguishing system, an underwater device and a lithium battery fire extinguishing method.The lithium battery is arranged in an energy cabin section of the underwater device, the fire extinguishing system comprises a fire detection tube unit, a fire extinguishing agent unit and a comprehensive management unit, the fire detection tube unit comprises a fire detection tube body, a pressure source and a pressure sensor, and the pressure source and the pressure sensor are arranged at the two ends of the fire detection tube body; the fire extinguishing agent unit is arranged on the underwater device and internally contains a liquid fire extinguishing agent. The fire extinguishing agent unit is connected with the fire detection pipe body and the energy cabin section. The comprehensive management unit is connected with the fire extinguishing agent unit and the pressure sensor and used for judging the fire occurrence moment according to the pressure change rate measured b