Hybrid vehicle extrication made simple
Systematic extrication process is compromised by vehicle variation and changing technology
Hybrid vehicles present unique challenges to rescue personnel; primary among those is the operating systems' lack of uniformity. The location, purpose, hazard and management of these systems vary among vehicle makes and models, making it difficult for rescuers to have a systematic approach to their extrication sequence.
Additionally, the technology behind these systems is constantly evolving, requiring vigilant pursuit on our part to be educated and prepared for these types of events.
A systematic approach is the objective because it develops consistency, speed and safety within the rescue sequence. Rescuers must first learn some fundamentals and general concepts to start working towards that objective.
Tools to have
The first step in a successful extrication is having the proper tools at the ready. There's no time to be running back to the truck for this tool or that tool. Here's the equipment you'll need on every hybrid vehicle extrication.
Let's lump hybrid vehicles into two categories: electric or alternative fuel. The electric category contains any vehicle that uses an electric motor for any form of propulsion. The alternative fuel category encompass any vehicle that uses a fuel source other that gasoline, diesel or a very similar derivative for propulsion.
All electric hybrids use a combustion engine in conjunction with the electric motor or they are simply electric cars and not hybrids. The electric hybrid is much simpler to analyze because it has less variables than alternative fuels.
Passenger vehicle manufacturers produce emergency response guides for their hybrid vehicles. These are a vital resource to rescue personnel as they provide hazard and high-strength steel locations as well as shut down procedures.
The guides can be accessed through boronextrication.com or the manufacturers themselves. There are also mobile apps such as EX field guides that are condensed versions of the ERGs.
The guides are a tremendous research and planning tool, but are not always effective on scene. When lives are in the balance and seconds count, we can't always open our reference material and call time out until we find what we are looking for.
Additionally, we can't expect rescue personnel to memorize every ERG and simply tap into his or her memory Rolodex. The only real option is to attempt to develop as many commonalities between these vehicles as possible and use them as standard considerations and approaches.
Some of those common considerations involve two electric systems, the ignition system and the large batteries.
Two electric systems
Hybrid electric vehicles use two electrical systems: low and high voltage. The low-voltage system typically powers the combustion engine, and the high-voltage system powers the electric motor as well as other items such as the air conditioning system.
These systems operate on a closed-circuit or loop that becomes neutralized as soon as the circuit is opened. Disconnecting or shutting off contacts opens the circuit.
Manufacturers' shut down procedures vary regarding how many contacts or circuits should be opened to insure shut down. Because of this, err on the side of caution and shut down as many as possible. The following actions will shut down the high-voltage system:
- Turn off the ignition and remove the keys.
- Disconnect or cut the positive cable from the low-voltage or 12-volt battery.
- Disconnect the fuse, relay or off/on selector switch for the IPU or high-voltage system. This is not always possible because some hybrids do not provide reasonable access to this component.
The ignition system
The ignition and the low-voltage (12-volt) system are the most accessible and identifiable but may require some digging. The ignition or the "running or not running" status of the vehicle should be addressed first.
Hybrid vehicles may be running at a stopped position with very little evidence of such. The audible hum and vibration of a combustion engine are not present, so approach with caution.
Whether the ignition is engaged through a proximity key, standard ignition key or a push button, the instrument clusters on the dashboard will be illuminated if the car is on. Turn the car off. The 12-volt systems may be located in the rear cargo space, the engine compartment or under the rear seats.
It's imperative to neutralize the 12-volt system not only to address the high-voltage system, but to neutralize the airbag hazard. As with all passenger vehicles, dual-stage airbags may have malfunctioned and could fire even after they have deployed.
The airbag operating systems also retain energy for a short time, which varies between manufacturers. These systems draw energy from the 12-volt system, so always remove their power source when possible.
High-voltage systems use large high-voltage battery units designed to withstand impact. Colored high-voltage cables (typically orange) carry electricity from these units to the electric motor, which is typically located in the engine compartment.
These cables travel along the vehicle's undercarriage; they may be located near the rocker or frame rails or centralized near the transmission or exhaust system. They are covered with protective coatings and, in many cases, shrouds that provide additional protection.
Do not cut or make contact with the high-voltage cables. Identify and avoid this cable during extrication operations. Even when the high-voltage system has been shut down, static charges from extrication tools contacting the cable could theoretically result in electrocution.
High-voltage switches are typically located near the high-voltage battery unit or IPU. These switches may be readily accessible or they may be buried beneath upholstery and bolted covers.
High-voltage relays or fuses are generally located in a fuse box or in a container in the engine compartment or along the firewall. These may be clearly marked or may require the owner's manual or ERG to ascertain which fuse or relay is the desired one.
If we use these known factors and eliminate the unknown or inconsistent factors, we can assume the following and develop a systematic approach to prepping a hybrid vehicle for extrication.
- Perform normal size up and stabilization actions.
- Identify the vehicle as a hybrid and turn it off. Ensure that the instrument cluster is not illuminated and remove the keys (at least 20 feet from the vehicle for proximity keys).
- Access the 12-volt battery and disconnect or cut the positive cable; the engine compartment is the most likely location. If the 12-volt isn't there, progress to the rear cargo space and then under the rear seat.
- With most of the manufacturers, these two steps are adequate actions to neutralize or shut down the vehicle.
- To be cautious and add another layer of safety, during these first two steps look for the high-voltage systems and either the fuse and relay components or the breaker switches. If appropriate during these initial actions, have nonessential personnel use the ERG to help identify, locate and perform the additional high-voltage shut-down procedure.
- Do not cut or contact high-voltage cables at any time.
Cutting and spreading
Once this progression has been followed, the vehicle has, in essence, been converted to a normal passenger vehicle. The body and SRS components of hybrid vehicles do not have any design characteristics that differ significantly from normal passenger vehicles when it comes to extrication techniques.
The high-voltage system location however may alter extrication techniques. For example, some hybrids have placed the high-voltage unit behind the rear seat of the vehicle.
This would largely negate the possibility of tunneling through the rear seat. Another consideration would be tunneling through the floor where the high-voltage cable is present.
One other area that may present a slight challenge or variation is venting material that can be imbedded in the sail panel or C post. High-voltage units produce a lot of heat and require venting to dissipate the heat.
This is typically a plastic vent configuration with insulation that progresses from the high-voltage unit to the vent point. When cutting the C post in a four-door vehicle or B post in a two-door vehicle, this material may bog down a reciprocating saw or be difficult to get through cleanly with hydraulic cutters.
Identify all of these components and plan accordingly.
Watch the attached video featuring Ross Baker from Rescue Methods and Justin Acton from Germain Honda of Dublin, Ohio. Acton is a hybrid vehicle consultant for Rescue Methods and a tremendous resource for rescue personnel.
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