Can a New Energy Vehicle Start After Being Submerged in Water?

[MacTanner]

New energy vehicles may or may not start after being submerged in water. Methods for dealing with different levels of water submersion: When designing the three-electric system, new energy vehicles fully consider the importance of sealing functions, with a sealing level generally rated at IP67. In power battery testing, the battery is required to be fully charged and then completely submerged in a 3.5% sodium chloride solution for 2 hours, followed by an observation period of 1 hour to ensure no fire or explosion occurs. Therefore, theoretically, new energy vehicles can withstand being submerged in water. Methods for dealing with minor water submersion: If the submersion is not severe and there is no water in the engine compartment, drive to a repair shop as soon as possible to clean the chassis and perform ventilation treatment. However, during actual water submersion, the power battery is usually installed at the vehicle's chassis position, and the water often contains a large amount of sand and impurities. The road conditions underwater are also difficult to assess, making it easy for foreign objects to damage the vehicle's insulation and sealing layers. Thus, safety during actual water submersion is hard to guarantee.

[Gollum]

Last time, my colleague's electric car got flooded during a heavy rainstorm and had to be towed to the 4S shop. The mechanic explained it very clearly: the biggest fear for new energy vehicles is water damage to the high-voltage battery. Even if the water doesn’t completely submerge the battery pack, just having water enter the wiring harness connectors can cause insulation failure. Nowadays, cars are designed to automatically cut off power when a short circuit is detected, leaving no chance to start the car. I heard that flooded battery packs, when opened, are full of white crystalline deposits, making repairs more expensive than replacing them entirely. My advice to everyone is: if your car gets flooded in a heavy rain, don’t take any chances trying to start it—just call your insurance company to handle it properly.

[MarcusAnn]

Last year, I personally witnessed an electric vehicle submerged in the flooded underground garage of our neighborhood. When the owner attempted to start it, blue sparks emerged from the chassis. Nowadays, the high-voltage systems of new energy vehicles are equipped with intelligent detection functions. The Battery Management System (BMS) automatically locks the system upon detecting circuit abnormalities. Be cautious if the water depth exceeds the centerline of the wheel hubs. Although the vehicle itself has an IP67 waterproof rating, prolonged submersion can cause the seals to fail. The most concerning issue is hidden damage—if a battery cell gets flooded and continues to be used, it may suddenly short-circuit and self-ignite months later. Remember, after submersion, the vehicle must be dried for at least three days, and the insulation resistance must be tested with a megohmmeter before restoring power.

[LeAliyah]

An experienced mechanic at the auto repair shop taught me some tricks: After a new energy vehicle has been through water, check the charging port for any water stains and feel the high-voltage wiring harness connectors for moisture. The repair bill for water damage to the electric drive system is terrifying—just the labor cost for removing and reinstalling the battery pack is 6,000 yuan, not to mention the expense of replacing the control module. Nowadays, vehicles with 400V/800V platforms are even more delicate; rainwater seeping into the DC-DC converter can render it completely useless. Don't believe the nonsense about letting it dry naturally and then driving it. I've seen cars that were left to dry for two weeks trip the charging station's protection circuit as soon as they were plugged in.