The EV Fire Defense Robot is an autonomous firefighting robot designed to suppress thermal runaway within electric vehicle battery packs. It autonomously approaches the vehicle, positions itself beneath the battery, and deploys a compact module equipped with an alloy penetration nozzle. Using an electro-hydraulic mechanism, the nozzle penetrates the battery casing and sprays extinguishing fluid directly onto the battery pack. This direct spraying method enables rapid suppression, reduces the risk of re-ignition, and minimizes water consumption and contaminated spills. Supporting both autonomous and remote operation, the EV Fire Defense Robot protects firefighters from heat, toxic gases, and explosion hazards in enclosed environments such as parking lots or charging stations.