Responding to Incidents Involving Hybrid and Electric Vehicles

Published Date: 
02/16/2014
Purpose: 

This procedure identifies operational tactics for safe handling of electric drive vehicle (EDV) fires and provides all department personnel with operational guidance when responding to incidents involving electric and hybrid vehicles.

Scope: 

This procedure is to be adhered to by all department members responding to emergency incidents involving hybrid and electric vehicles. This SOP addresses standard vehicle disabling techniques as well as handling crashes, extrications, fires and submersions. It is recommended that all personnel receive formal training on the subject in addition to reviewing this SOP. Due to the dynamic nature of hybrid technology this SOP should undergo an annual revision to make sure the response information remains current. Vehicle specific procedures should be referenced in the NFPA EFG or manufacturer ERGs.

Definitions: 
  • HEV – Hybrid electric vehicle
  • EV – Electric vehicle
  • xEV – Represents any vehicle which utilizes an electric drive system
  • EFG – Emergency Field Guide
  • ERG – Emergency Response Guide
  • Occupant Protection Systems – Consists of airbags, seatbelts, seatbelt pretensioners, rollover protection systems and other devices used to ensure occupant safety in the event of a crash
  • Regenerative Braking System – Allows xEVs to generate electricity to be placed in the high voltage battery during braking.
Procedure: 

A. Initial Response Actions

Use standard scene size-up techniques and then use the following steps.  Be sure to consult the NFPA HEV and EV emergency field guide (EFG) or manufacturer specific guide for vehicle specific procedures and instructions.  Variations to this process may exist based on vehicles involved and specific scene conditions.

Identify -> Immobilize -> Disable

1)   Identification

Hybrid and electric vehicles can usually be identified through a variety of badging or design features found on both the interior and exterior of the vehicle.  Always assume that a vehicle operates on some type of alternative propulsion system until proven otherwise.  Once identified, make sure all personnel on the scene are aware that the vehicle is a xEV.

Exterior indicators can include emblems containing the words hybrid, electric, EV, hybrid synergy drive, integrated motor assist (IMA) etc.  Others may only indicate the vehicle’s model name such as Volt or Leaf.  Some models may have no exterior badging at all. In some instances a vent for the high voltage battery or a charging port may be visible from the exterior of the vehicle.  Always consider that exterior markings may have been hidden/damaged by a crash or fire.

Interior indicators are usually found on the dashboard and will contain the same key words as the exterior badging.  Also, gauges on HEVs and EVs will differ from a conventional vehicle and may indicate level of battery charge or mode of operation.  A “ready” or “autostop” status indicates that the vehicle is “on” and will move if placed in gear.  In some models high voltage battery vents can be found between the rear deck speakers.  High voltage warning labels and orange wiring can be found under the hood, on the underside of the vehicle and in the high voltage battery storage area.

2)   Immobilize

All vehicles need to be immobilized at an emergency scene.  HEVs and EVs present an additional concern in that they can appear to be shut down while in fact they are on and ready to move.  Use the following steps:

a)   Chock the front and rear of the most accessible tire.

b)   Set the vehicle’s parking or emergency brake

c)   Ensure the vehicle is in park

3)   Disable

Shutting down the vehicle’s drive system renders it unable to move under power and contains high voltage current to the battery itself.  Most vehicle shutdown procedures recommend one of the following methods, in the order given.  However, always consult the NFPA EFG or manufacturer’s ERGs for vehicle specific instructions.  In each method, BOTH steps must be accomplished to fully disable the vehicle and its occupant protection systems.

a)    Method #1 (ignition accessible)

(1)  If vehicle is on remove key from ignition or use power button to shut it down.  Maintain control of the key or power button until the 12v battery is disconnected to prevent accidental starting of the vehicle.

(2)  Disconnect the 12V battery

Awareness Point
Several manufacturers whose vehicles are outfitted with proximity keys recommend removing the key from the vehicle at a distance of 16 feet to disable the system. This key may be in a difficult to access location and consideration must be given to the potential of more than one key being in the vehicle. The most operationally effective method of disabling the proximity key system is to disconnect the 12v battery once the vehicle is shut down.

b)   Method #2 (ignition not accessible)

(1)  Disconnect 12v battery

(2)  Pull the high-voltage system control fuse typically found in the engine compartment fuse block. (Consult EFG or ERG for location)

Awareness Point
Dissipation times for the high voltage circuit can be up to 10 minutes after the shutdown is initiated.  The high voltage battery always remains energized, even after the high voltage circuits are disabled.

Some manufacturers recommend removing the manual service disconnect located on the high voltage battery in the event these methods cannot be used or as an additional safety measure.  Always consult the EFG or ERGs for the requirements for this procedure as well as required PPE as they are manufacturer specific.

 

B. Crash and/or Extrication Operations

Standard department SOPs regarding operations at vehicle crash/extrication are to remain in effect with the following considerations:

  • HV components/cabling is typically not found in typical “cut points” and generally will not pose an obstacle to standard extrication evolutions. 
  • Orange high voltage cables and components must not be cut or disconnected. 
  • As always, personnel must maintain situational awareness, especially with HV components. 
  • Severe damage to the vehicle may have shifted wiring and components. 
  • Standard stabilization methods are acceptable; crib at vehicle structural points and avoid high voltage components or fuel lines.
  • Certain specialized extrication techniques such as trunk tunneling and a through-the-floor entry may not be possible with some vehicles due to the location of their high voltage batteries. 

 

C. Battery Breaches

Although a potentially rare occurrence, in the event that a high voltage battery is breached consider the following:

  • DO NOT touch or handle damaged HV Battery – Shock Hazard! 
  • Batteries are dry cell; even if crushed electrolyte release should be minimal
  • Electrolyte can be caustic or flammable
  • Liquid cooled batteries may release their coolant if breached giving the appearance that a large amount of electrolyte has been released. 
  • Watch for unusual odors or eye, nose, throat or skin irritation; if detected, don SCBA.
  • Monitor damaged high voltage battery for gurgling or bubbling noises, smoke, leaks or sparking.  These are signs of potential overheating and create a risk of off-gassing and fire.
  • If damage to the HV battery is suspected, ventilate passenger and cargo areas

 

D. Vehicle Fires

Fires in xEVs will produce similar hazards and toxic substances to those found in conventional vehicle fires.  NFPA approved firefighting ensembles including SCBA shall be used at all vehicle fires.  No special equipment or extinguishing agent is required to extinguish xEV fires although tactics may need to be adjusted based on the nature and location of the fire within the vehicle.  Utilize the Identify, Immobilize and Disable approach as soon as possible during firefighting operations.

Consider the following:

  • Water is an acceptable extinguishing agent
  • Avoid coming into direct contact with high voltage components or wiring in order to prevent potential injury.
  • Do not blindly breach areas such as the hood or trunk areas as it may result in contact with high voltage components or wiring.

Awareness Point
Unlike in a structure, application of water to put out a xEV fire is an acceptable practice. Due to the fact that the high voltage system is isolated from the vehicle chassis and that the vehicle electrical system is not grounded, the electrical current does not travel down the hose stream.

xEV Fire with no High Voltage Battery Involvement

Fires in HEVs and EVs, when the high voltage battery is not involved are generally handled in a similar manner as a conventional vehicle fire, using the additional considerations noted above.  These types of fires typically consist of the same types of materials being burned as in a conventional vehicle, with the exception of the lack of a hydrocarbon fuel in an EV.  Upon extinguishment of the fire it will be necessary to determine if the high voltage battery was involved.  This can be done through visual inspection of the area as well as through the use of a thermal camera if the battery case is visible. If you have reason to believe the battery is involved use the procedures listed below.

xEV Fire with High Voltage Battery Involvement

Once the high voltage battery is ignited, firefighting personnel should anticipate an increased extinguishment time and water volume required to fully extinguish the fire. 

Consider the following:

  • Secure an adequate water supply from a hydrant, static water source or by requesting additional apparatus to the scene.

Awareness Point
Tests conducted on burning EV batteries indicate that upwards of 2,600 gallons of water may be required for extinguishment.    

  • Volume of water required is dependent on the size of the battery, its level of fire involvement and its location within the vehicle.
  • If adequate water supply is not available, a defensive approach should be utilized to protect any potential exposures.  Use of an offensive attack could result in running out of water prematurely and re-ignition of a fire without any water left over to protect potential exposures.
  • For quicker extinguishment of a high voltage battery fire, keep a continuous application of water on an area that is burning for a prolonged period of time before moving to another section of the battery.  Also, continue to apply water even after flames are no longer visible in order to sufficiently cool the battery pack and reduce the risk of re-ignition. 
  • Never pierce, cut, pry or dismantle any of the vehicle’s structure, including the floor pan, to get water directly into the battery because you may come into contact with a high voltage component risking potential injury.

 xEV Fire while Connected to a Charging Station

  • Treat as a standard energized electrical fire.
  • Use class C extinguishing agents if the charger is still energized.
  • Locate and shut down charging station power source (lock out/tag out) prior to using water as an extinguishing agent.
  • Once electrical power to the charging station is secured, use the methods outlined above to extinguish the fire.

Post Fire Considerations

  • Before removing a vehicle from the scene monitor the battery area for any hissing or popping noises and smoke.
  • The potential for re-ignition of the high voltage battery exists if it is not adequately cooled down.
  • If there is visual access to the high voltage battery use a thermal imaging camera to determine if the battery has cooled down or if it is getting hotter over time.

Awareness Point
The usefulness of thermal cameras is limited by your ability to visually access the battery case.      

  • Do not perform overhaul operations in any areas where high voltage cables or components are present.
  • Because of the possibility of re-ignition, NHTSA and National Fire Protection Guidelines currently recommend vehicles be kept at least 50 feet from any combustible materials when stored post fire or if there is any damage to a high voltage lithium ion battery.  The goal is to protect any potential exposures should the battery reignite.
  • xEVs should be transported via a flatbed to avoid potential overheating in the regenerative braking system.

E. Vehicle Submersion

Remove vehicle from water and use standard disabling techniques.  The high-voltage system is isolated from the vehicle chassis so there is no risk of electric shock from touching the car’s body or framework in or out of the water.  Do not touch high-voltage components or cables directly.  Do not remove the high voltage disconnect while vehicle is in the water.  Consult the NFPA EFG or manufacturer’s ERGs for additional information on handling submerged vehicles.