Can you be electrocuted by an electric vehicle?

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A US-made electric car would fully comply with safety codes and standards, says a Northeastern expert. Credit: Matthew Modoono/Northeastern University

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A US-made electric car would fully comply with safety codes and standards, says a Northeastern expert. Credit: Matthew Modoono/Northeastern University

Electric cars, scooters and bicycles are everywhere. Are they safe? A Northeastern expert analyzes the safety of EV and lithium-ion batteries when they come into contact with water.

It is highly unlikely that a Tesla submerged in a pond in a recent fatal crash in Texas posed a threat of electrocution to the driver or rescuers, says a Northeastern University expert.

Angela Chao, 50, a shipping company CEO and sister of former Transportation Secretary Elaine Chao, died last month in her Tesla after her car crashed into a pond on a Central Texas farm.

The vehicle was completely submerged, according to a report obtained by the Austin American-Statesman, and it took firefighters about an hour to extract Chao from the car. She was pronounced dead at the scene.

To get into the Tesla, firefighters stood on top of the submerged vehicle while trying to break into the car through the windows, according to the report. A tow truck could not pull the car to the edge of the pond because the chains were not long enough.

Can an electric vehicle immersed in water pose a risk of electrocution? Were the rescuers in danger?

Sanjeev Mukerjee, professor of chemistry and chemical biology and affiliated faculty in Northeastern’s chemical engineering department, says battery compartments in electric vehicles like Tesla are completely sealed and well protected.

According to the U.S. Department of Energy, most electric vehicles, as well as most portable consumer electronics such as smartphones and laptops, as well as electric scooters and e-cigarettes, are powered by lithium-ion batteries. Lithium-ion batteries store more energy per unit mass and volume and have a high power-to-weight ratio, high energy efficiency, good high-temperature performance, long service life and low self-discharge.

An EV battery, Mukerjee says, can be damaged or punctured by a sharp object in an accident. In that case, the electrodes with the opposite charge can touch each other due to damage, causing a path reaction.

The battery would overheat as all the electricity was released at once during the uncontrollable process. The battery’s temperature can quickly rise to 900°C, or more than 1,650°F, Mukerjee says, and the battery can catch fire or explode.

When an electric vehicle goes underwater, Mukerjee says, the water is unlikely to get into the battery compartment.

“There are codes and standards regarding electric vehicles, which mainly relate to a battery pack and how it is protected and sealed,” he says.

A US manufactured vehicle would fully meet these requirements. In the case of Tesla vehicles, they are equipped with a number of built-in sensors that can disable the battery in the event of a collision or rollover.

“It’s an engineering marvel,” says Mukerjee.

Mukerjee says he is more concerned about electric scooters and electric bicycles, which also have lithium-ion batteries. They do not have proper battery protection against damage, unlike electric cars.

“If you see little scooters outside in the rain,” he says, “I would be concerned about that [more] than I would worry about a car.”

If a car falls into water, it first impacts the charging port, he says, which is designed to isolate itself if a short circuit occurs. The same would happen with a damaged cable.

“So there are safety guidelines built into a Tesla at every point,” says Mukerjee.

First responders still need to know that the submerged car is an electric vehicle, he said, before attempting a rescue. The U.S. Department of Energy is providing resources for emergency responders to receive training on electric vehicle safety, and at least some fire academies are training their students as well.

“If they comply well with safety standards, whether it is an accident or a submersion, [they should be safe]’ says Mukerjee.

The first thing rescuers need to know, he says, is where the battery is and make sure it isn’t damaged during the rescue. This can happen if rescuers try to lift the vehicle or smash through it with an ax or other tool they may use.

Rescuers should also be on the lookout for any high-power rails – rigid conductors used to connect different circuits – that connect parts of the car to the electronic computer.

“They are sealed, but if they are damaged, stay away from them,” says Mukerjee. “They can give you a severe electric shock.”

The passenger compartment is also insulated against electric shock and is safe for the driver and passengers.

‘Any reasonable electric vehicle [manufacturer] will ensure that the passenger is isolated and grounded because sometimes there are people in the car when the car is charging,” says Mukerjee.

On land, water is also unlikely to cause electrocution from an electric car. When charging the car at a charging station, the driver must visually check the cable for damage. If the cable is damaged, Mukerjee says, it’s best not to plug it into the charging port.

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