Rising fuel costs have increased interest in hybrid vehicles. In fact, some estimate that 5.2 million hybrid vehicles will be on the road by 2011, with more than 50 models available by 2012.

Hybrid vehicles present new concerns for to emergency responders, but proper education and training can minimize risks. A department that has response procedures in place for handling standard vehicle accidents is well ahead of the game, as many of the precautions remain the same. However, SOPS need to be updated to include specific information on responding to incidents involving hybrid vehicles.

All but two of the available hybrid models were designed using pre-existing model chassis, so emergency responders must always consider that even familiar looking vehicles could be hybrid. The Honda Insight and the Toyota Prius are the only models designed solely as hybrids. (Insights were produced only through the 2006 model year.)

Identifying a hybrid essentially can be broken down into two methods: formal and informal. Formal methods include the search for hybrid “badges” or logos, and informal methods focus on characteristics of a hybrid not found on standard vehicles.

Hybrid logos typically are found on the rear of the vehicle or on the front or rear doors — areas often damaged after a collision. The words “Hybrid” or “IMA” may be found on plastic cowling in the engine compartment or on the dashboard or display inside the vehicle. However, rescuers shouldn't assume that a vehicle isn't a hybrid because there's no immediately visible emblem. For example, the Lexus RX400h doesn't use a traditional hybrid emblem; only the “h” in the model name signifies the vehicle is a hybrid.

There are several informal identification methods that also can be helpful to responders. The most notable is the car manufacturer's use of the orange cable for high-voltage lines. These cables can be found in the engine compartment, on the underside of the vehicle and in the battery area. Use caution, however, when looking for the orange cable on the underside of the vehicle.

Many manufacturers have covered up a good portion of the colored cable with cladding. Several models, such as the Ford Escape, Mercury Mariner and the Toyota Highlander, have only a few inches of visible orange high-voltage lines. The Nissan Altima Hybrid's emergency response guide indicates that the high-voltage cables under the vehicle are encased completely in a black plastic protector. High-voltage warning labels or symbols should be visible in the areas where the orange cables are present. Hybrids also may use yellow medium-voltage cables to power air conditioning and power steering features. Blue medium-voltage cables can be found in some start/stop hybrid systems, such as in the Saturn Vue Hybrid.

Another less obvious identifier is visible battery vents. Because the continual discharge and recharge of the high-voltage battery system produces heat, car designers have incorporated vents to help cool the batteries. Typically these vents are located in the relative vicinity of the battery pack for efficiency. Not all models have vents that are visible, but responders should be on the lookout.

Dashboard indicators may include a status gauge that indicates whether the battery is being charged or assisting with vehicle propulsion. Rescuers also may come across a kw gauge which replaces the standard rpm gauge. Several models have some type of ready indicator incorporated into their dash, which indicates to the driver that the vehicle is on and ready to move even if the engine is off.

In addition to the high-voltage wiring, a hybrid system features two other main components: the electric motor/generator and the high-voltage nickel metal hydride battery pack. The electric motor helps propel the vehicle and recharges the batteries, depending on the mode it is in. The batteries are recharged either using power from the gasoline engine or through regenerative braking, a process in which the energy typically wasted during braking is used to drive the electric motor in its charging mode.

High-voltage batteries typically are located behind the rear seat in the sedans or under the rear seat or rear cargo area in sport-utility vehicles. NiMH battery modules can range from 144 to 330 volts dc. A number of single hv cells are arranged into a stick, and several of these sticks are combined to make a battery module. Each individual cell is roughly the size of a d-cell battery. These batteries are considered a dry cell and don't present a significant spill hazard. The electrolyte, consisting of potassium and sodium hydroxide, is absorbed into cell plates to form a gel that shouldn't leak, even after a collision. If the battery is crushed, however, it is possible for electrolyte drops to leak. All hybrid models also use a 12-volt battery system to power low-voltage vehicle systems.

Most hybrid models have safety switches that automatically cut high-voltage power to the system when supplemental restraint systems are activated during a collision. If the system short circuits, a fuse will open and cut off high-voltage power from the battery. The positive and negative cables are isolated from the chassis to prevent any type of electrocution hazard from touching the chassis itself. The automatic shutdowns only handle high voltage from the battery to the electric motors; the batteries themselves remain energized. The hybrid system also is shut down when the ignition is turned off, the battery is disconnected or the high-voltage system fuse is removed.

Some battery models contain a boost converter that takes the DC power and coverts it to 650-volt AC power to run the electric motors. Testing has indicated that high-voltage systems can remain energized after being subjected to fire. Rescuers should avoid contact with high-voltage components and never attempt to disconnect any high-voltage connections. The same precautions should be used for any yellow or blue medium-voltage cables as well.

Rescuers also should avoid contact with damaged battery packs and any electrolytes that may have been released. The damaged battery pack still could be energized and the electrolyte can cause skin/eye irritations and burns. CHEMTREC has Material Data Safety Sheets on the batteries, if that becomes necessary. Toyota, Lexus and Nissan ERGS also contain information on how to neutralize a leak and first-aid treatments for electrolyte exposure.

The most common danger emergency responders will face is the hybrid's ability to move instantaneously even though the vehicle appears to be off. A hybrid can shut down the gasoline engine when the vehicle is idling. This could give a responder the impression that the vehicle is off, creating a false sense of security. Establish procedures to control this potential movement before rescuers put themselves in front of or behind the vehicle.

Accidents & extrications

Response to an accident involving a hybrid vehicle should proceed almost exactly as a normal response. Responders will find that if they follow industry accepted procedures for handling motor vehicle accidents they will have already remedied the majority of the problems presented by hybrids.

During the scene survey, responders should look for the presence of a hybrid vehicle. As with standard vehicles, responders never should approach from the front or the rear until they are sure that the vehicle has been immobilized and disabled; this is especially true for hybrids. Immobilization can be achieved by chocking the vehicle, placing it in park and then setting the emergency brake.

There are no extrication techniques specific to hybrid vehicles, but operations must take into consideration the location of high-voltage components. Manufacturers have placed the high-voltage cables and batteries in locations that responders don't consider cut points. The rescuer should consider, however, the a collision may have pushed high-voltage components close to necessary cut points. At no time should a responder attempt to disconnect high-voltage components, touch damaged or broken orange cables, cut high-voltage lines, or touch a damaged battery. To ensure safety, responders always should treat high-voltage cables as if they are energized.

Hybrid vehicle manufacturers recommend one of two options to disable the high-voltage system. Either of these steps causes a relay to open and prevents power from the entering the rest of the high-voltage system. The first method — and the simplest — is to remove the key from the ignition and disconnect the 12-volt battery. The second method, used if access to the ignition key is not a viable option, is to disconnect the 12-volt battery and to pull the high-voltage system fuse in the engine compartment fuse box. Because the first responder may not be able to immediately identify the correct fuse, as the color-coding differs between models, he or she should pull all the fuses. This is not the actual high-voltage line fuse; it's simply the fuse that powers the relay in the high-voltage system.

Department SOPS already should dictate that the ignition key is removed and the battery disconnected to shut down supplemental restraint systems. If this procedure is in place, responders already are handling the major concerns of dealing with a hybrid. Bleed down times for hybrid systems are five to 10 minutes, depending on the manufacturer. Keep in mind, however, that this doesn't disable the high-voltage battery, and power remains in the NiMH battery module.

Vehicle fires

Vehicles fires in hybrids can be handled in accordance with the recommended practices of the National Fire Protection Association, International Fire Service Training Association and the National Fire Academy. Water is the most suitable agent for extinguishment. Although applying water to a high-voltage electrical system seems counterintuitive, there is no risk of the electricity traveling up the water stream and electrocuting firefighting personnel. Although still dangerous, direct current power sources don't need a path to ground, unlike alternating currents. Rather, DC electricity follows a path out from the battery, along the electrical circuit and back to the battery. As such, the electrical current will not travel up the hose stream as is possible with a high-voltage AC power source. The danger of electrocution exists when firefighters accidentally place themselves into the electrical circuit by simultaneously touching the negative and positive side of the circuit with either their body or equipment.

A standard offensive attack is recommended unless the NiMH battery pack is on fire. If this is the case, live-fire tests indicate that it is better to allow the battery to burn out rather than attempt to extinguish it. It's nearly impossible to get enough water directly onto the battery for extinguishment because the battery is encased in protective shell. The only real access for water to the battery pack is via the battery vent, and many vent designs hinder easy access for this. Allowing battery pack to burn out also negates hazmat concerns over the residual electrolytes. Always make sure that the battery pack is cooled down enough to prevent re-ignition before releasing the vehicle. Thermal-imaging cameras can help determine if the battery pack is cooled down.

Attempts should be made to control runoff as the NiMH battery has cancer-causing ingredients. If a defensive attack is warranted, responders should pull back to safe distance and use a water stream to protect exposures and control the path of smoke. If the situation doesn't allow for a defensive attack, such as a vehicle in a garage, appropriate actions should be taken.

High-voltage components never should be overhauled, as there is no guarantee that the system is de-energized. System safeties can be rendered inoperable by the effects of fire. Live-fire tests indicate that these components can remain live after a vehicle has been subjected to fire.

One final area of concern for responders is submerged vehicles. Hybrid-vehicle manufacturers recommend removing the vehicle from the water and using standard disabling techniques. There is no risk of electric shock from touching the vehicle's body or framework in or out of the water. As with a vehicle out of the water, responders should not touch high-voltage components or cables. All of the Hybrid ERGS address vehicles in the water.

Model specific

As more and more hybrid models are released it's important that emergency responders educate themselves on the unique dangers these vehicles present and the methods by which to address them. Responders should not fear hybrid vehicles, as they present minimal risk as long as firefighters follow proper procedures. Department SOPS should be modified to address particular issues pertaining to hybrids.

There are several items to consider when dealing with specific models of hybrids. The manufacturers' emergency response guides should be consulted for specifics. The Ford Escape and Mercury Mariner have battery service disconnects that are accessible to emergency responders under the rear cargo area carpet. Likewise, the Nissan Altima has a service disconnect in the trunk. Chevy Silverado and GMC Sierra also have a battery disconnect for their hybrid systems under the rear seat on the passenger side of the vehicle.

Vehicle ignition systems on certain hybrid models also can differ from what we are accustomed to. The Toyota Prius uses a slot in the dash which accepts a rectangular “key” and the vehicle is turned on using a power button. Another concern for responders is the “smart” or “intelligent” keys. These keys operate the door locks and the ignition remotely and only have to be in proximity to the vehicle to function. The ignition is turned on using a button on the dashboard and will only function when the key is present. These keys need to be removed to a minimum of 16 feet from the vehicle to prevent the ignition from being activated by the push button. These keys can be found in the Toyota Prius and Camry, Lexus 450h, and Nissan Altima. The Prius has a disable button for this smart key system which can found on the dash under the steering column. This is the only hybrid vehicle that uses this disable feature.

The ERGS are readily available on the Internet and or can be downloaded at www.etsrescue.com/hybrid_guides.exe. Departments should make these guides and formal training available to their members to ensure that they get the proper information. As with anything in the fire service proper education is paramount.

---

Jason D. Emery is the director of training for Emergency Training Solutions.