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Safety risks in electric vehicle crashes: Suggestions for law enforcement officers on the scene of a serious wreck

You are the first officer at the scene of a serious vehicle crash and you suspect one of the damaged vehicles is a hybrid or fully electric vehicle. There may be people still inside and bystanders milling about. What is the first thing you do?

Answer. Chock the wheels.

Unlike internal combustion engines, there are few signs that an electric vehicle is still “running”. If the battery pack is still energized and the ignition system is still on, one touch of an accelerator pedal may cause it to move without warning.

There are multiple risks inherent with vehicles equipped with high-voltage lithium-ion battery packs, as found on most hybrid and plug-in electric vehicles. This author checked with a few experts to give a quick summary on suggestions for the first law enforcement officers on the scene of a serious wreck.

As always, the science is constantly evolving, and this advice may change as greater standardization increases across the electric vehicle industry.

Firstly, the high-voltage lithium-ion (Li-ion) batteries in hybrid, plug-in hybrid and battery electric vehicles do pose a danger to first responders in crashes where the vehicle may be damaged or in cases where an electric vehicle is disabled. There is risk of electrocution if the battery pack or any of the high-voltage cables or connectors have been compromised. There is also a risk of thermal runaway if the battery pack catches fire.

1. Identify

Look for indications the vehicle may contain a high-voltage battery pack. Labels, brand names and even the lack of tail pipes might be an indication. Do not use the lack of sound as an indicator. Look instead for lights on the dash or instrument panel that may indicate the ignition is still on and the powertrain is still energized.

2. Approach

Approach the vehicle at a 45-degree angle and expect that the vehicle may start moving without warning at any time until it is immobilized.

3. Immobilize

Find a way to prevent the vehicle from moving before trying to extricate any passengers. Firefighters will have wheel chocks, but until they arrive, find anything to place under the front and rear of at least two wheels if they are still touching the ground.

If you can access the passenger compartment, set the parking brake, place the vehicle in Park and look for any “ready” indicator lights. If any lights are visible, push the ignition button to OFF. Once occupants are safely extracted, remove any key fobs, and keep the fobs at least 10 meters away. If occupants are conscious, tell them to not use any vehicle apps on their smart phones.

4. Watch, smell, listen

Watch for lights on the dash or instrument panel that indicate the powertrain is still energized. Look for any damaged high-voltage components or cables (high-voltage cables and connectors will be colored orange). If any orange cables or connectors are visibly cut or broken, move away from the vehicle and keep bystanders away due to a possible electrocution hazard. Listen for the sounds of bubbling that may indicate the high-voltage battery pack case may be compromised. If you smell toxic chemicals, move everyone away and do not approach unless equipped with full PPE.

If smoke appears in or near the battery pack, do not try to fight the fire with foam or chemical fire extinguishers as they will do nothing. If the battery pack catches fire, it creates what is called “thermal runaway” and the only way to fight the resulting fire is vast quantities of water.

5. Disable

In a serious crash, the vehicle may need to be completely disabled, which means isolating the battery pack completely from the chassis. Depending on the design, the battery pack is usually disconnected by pushing the ignition OFF. On some makes, it is automatically disconnected in a crash where the air bags are deployed. Most hybrid and electric vehicles are equipped with special cable cut points, where a low-voltage cable can be cut, thus disconnecting the high-voltage battery pack from the vehicle. These are often marked as “First Responder Cut Loop.”

Cutting or disconnecting the 12-volt battery also disconnects the high-voltage battery pack and isolates it from the chassis. Firefighters will have access to the proper PPE, special cable cutting tools and Emergency Response Guides as published by the vehicle manufacturer.

Do not cut or attempt to disconnect any orange-coloured cables or connectors. Orange is the universal designator across the industry for high-voltage components.

Submerged Vehicles

If the vehicle is still mostly intact, hybrid and electric vehicles are designed to be safe even when fully submerged in water. Once the high-voltage system is isolated from the chassis, it will pose little danger of shock or energizing surrounding water.

Attempt to turn the ignition off but do not attempt any other measures while it is still submerged. Do not touch, cut or disconnect any orange high-voltage cables. If the ignition cannot be turned off, first responders should wait until the vehicle is recovered and fully drained before attempting other methods of disabling it, such as removing the 12-volt negative battery cable or cutting the First Responder Cut Loop.

Once a previously submerged vehicle is recovered and stable, the wheels should first be chocked, and the vehicle placed into Park.

Emergency Response Guides for alternative fuel vehicles

The National Fire Protection Association (NFPA) has complied a free database of Emergency Response Guides for many makes and models of hybrid and electric vehicles. These can be found at: NFPA – Emergency Response Guides for Alternative Fuel Vehicles.

Dave Brown is a Blue Line contributor on firearms and police vehicles, as well as a Best Dressed Police Vehicle Awards judge. He is a tactical firearms trainer and consultant based in Winnipeg. He can be reached at Dave.Brown@northwestlaw.ca.