The back of the Prius rear seat consists of nothing more than a foam rubber seat cushion separating the interior of the car from the trunk area. Exposed to a fire within the passenger compartment, this seatback will burn and melt away, letting the battery pack in the trunk be exposed to the fire.

What emergency procedures should be taken at a fire involving a hybrid vehicle?

A fire involving a hybrid vehicle can be handled by following normal vehicle firefighting procedures. In a typical vehicle fire incident, the engine compartment, interior of the vehicle or trunk area are burning. By following generally accepted fire suppression guidelines, crews attack the fire with an adequate water flow rate, working from a safe position of approach. Self-contained breathing apparatus (SCBA) is worn throughout the fire incident. The wheels of the vehicle are chocked to prevent forward or rearward movement as soon as safely possible.

There are potential fire situations involving a hybrid that can present unique concerns. Any fire where there is direct flame impingement on the high-voltage battery pack would be one example. A fire that has originated within the battery pack itself or an electrical fire that begins somewhere within the high-voltage electrical system would also require special precautions.

The back of the Prius rear seat consists of nothing more than a foam rubber seat cushion separating the interior of the car from the trunk area. Exposed to a fire within the passenger compartment, this seatback will burn and melt away, letting the battery pack in the trunk be exposed to the fire.

Radiant heat could cause the plastic modules inside the high-voltage battery to melt just as any plastic material would when exposed to high temperatures. If heated sufficiently, it is possible that the plastic module casings could melt down, exposing the inner components of the high-voltage battery.

The fire service already has experience with lead acid batteries melting down during fully involved engine compartment fires. Unlike the meltdown of a 12-volt battery, however, responders who encounter a melted nickel metal hydride (Ni-MH) battery may want to notify the nearest Toyota or Honda dealership and ask that designated battery recovery specialists be notified so they may properly deal with the damaged battery after the fact.

Where a fully involved hybrid vehicle fire is encountered, copious (large and sufficient) amounts of water will generally be the extinguishing agent of choice. This will eliminate the radiant heat and begin cooling the metal battery box and the plastic battery cell modules inside the high-voltage battery pack itself. Fire suppression crews will not be shocked or electrocuted during direct attack on a hybrid vehicle fire, even if flames are impinging on the battery pack itself.

The high-voltage battery pack cells are sealed and protected by their metal battery cover. All high-voltage circuits are protected from accidental contact within a shielded cable covering and a plastic conduit. All high-voltage circuits and plugs for this system are marked, color-coded orange and posted with warnings to advise of their presence. No emergency responder should ever disassemble or remove the metal cover of the high-voltage battery pack.

Ni-MH battery pack fire. For advice on extinguishing a fire where the high-voltage battery itself is the source of the fire, we turn to a major user of Ni-MH batteries. In the Ni-MH Product Safety Data Sheet from Moltech Power Systems, responders are advised that virtually all fires involving Ni-MH batteries can be controlled with water. This information sheet also recommends, “In case of fire where nickel metal hydride batteries are present, apply a smothering agent such as METL-X, sand, dry ground dolomite, soda ash, or flood the area with water. A smothering agent will extinguish burning nickel metal hydride batteries.”

Most fire apparatus do not carry Class D extinguishers. Without one, water becomes the primary extinguishing agent for any type of fire scenario involving a hybrid vehicle. If your fire suppression plan is to use a Class D extinguisher, check it for compatibility with the Ni-MH battery.

Unfortunately for the fire service, the concern is that not all Class D fire extinguishers are created equal. Be aware that certain Class D fire extinguishers contain particles of metals such as copper. Copper, for example, is one metal that may actually cause an adverse reaction with the high-voltage battery and generate hydrogen gas. In a small space such as the trunk of the hybrid, this could cause an explosion. Any fire suppression efforts with Class D portable fire extinguishers should include agents that have no particles of metals mixed into their Class D agent. Check your Class D extinguisher now!

Large amounts of water, such as from an 13¼4-inch attack line, will not be able to directly attack a fire burning inside the battery pack unit itself. The metal cover of the pack prevents a direct attack on the internal cells of the battery. The water application, however, will cool the vehicle, control the spread of the fire and cool the adjacent battery cells. Burning Ni-MH batteries will burn themselves out, Moltech advises. For the fire service, apply sufficient quantities of water to the batteries to cool the metal housing of the battery pack and control the fire until the battery modules that are actually on fire burn themselves out. Do not remove the metal cover of the high-voltage battery pack.

Ni-MH battery pack physical damage. The high-voltage battery pack cells are sealed and protected by a metal battery cover. All high-voltage circuits are protected from accidental contact within a shielded cable covering and a plastic conduit. All high-voltage circuits and plugs for this system are marked, color-coded orange and posted with warnings to advise of their presence. No emergency responder should ever disassemble or remove the metal cover of the high-voltage battery pack.

The hybrid gasoline/electric vehicles pose no additional risks over a conventional vehicle if handled properly at an emergency incident. The electrocution hazard is removed because by design; the 144-volt or 300-volt DC current is normally isolated from any contact with the vehicle itself. In order to receive a shock, an emergency responder would have to physically contact two separate points within the high-voltage system at the same time.

If the parallel high-voltage cables running under the vehicle to deliver current to the front of the car were damaged as in a severe crash or fully involved fire scenario, the high-voltage battery would shortcircuit. This short would de-energize the entire high-voltage battery circuit.

All high-voltage circuits are protected from accidental contact within a shielded cable covering and a plastic conduit. All high-voltage circuits and plugs for this system are marked, color-coded orange and posted with warnings to advise of their presence. No emergency responder should ever disassemble or remove the metal cover of the high-voltage battery pack.

Potential hazmat considerations. There are several product information sheets for nickel metal hydride batteries. It is also appropriate to consider the Material Safety Data Sheets (MSDS) for potassium hydroxide for this situation. According to an MSDS-type information sheets available for Panasonic Ni-MH batteries, a battery fire will produce toxic fumes, including oxides of nickel, cobalt, aluminum, manganese, lanthanum, cerium, neodymium and praseodymium (see www.panasonic.com/batteries).

It has already been mentioned that firefighters should wear SCBA throughout the fire attack and overhaul. In addition, keep the “hot zone” clear of unnecessary personnel. Keep all hot zone personnel fully protected with structural clothing that addresses Level 3 hazmat personal protective clothing criteria.

All authorities agree that virtually all fires involving Ni-MH batteries or the hybrid vehicle itself can be controlled with water. When water is used, however, some hydrogen gas may evolve. In this situation, ventilation by leaving the trunk or hatchback lid open is advised. If there is concern that hydrogen gas is present, fire smothering agents such as those used by hazmat teams are recommended.

The high-voltage battery is in a somewhat protected position in both the Prius and the Insight. It will survive most every crash without physical damage due to its location above the rear axle. A violent crash, especially a side collision at the rear wheel, however, can crush or break open the internal cells of the high voltage battery. Be cautious if the high-voltage battery has been physically damaged or exposed to extreme heat impingement.

Under the hood of the Toyota, about midway along the top of the firewall, is a black plastic box. Remove the cover of this box. There are four electrical components inside. Remove the electrical relay on the far right (driver’s side). This relay is the IGCT Relay. Removing it breaks the power circuit from the high-voltage battery.

Any hybrid vehicle with a crushed or opened high-voltage battery should be “tagged” by the authority in charge of the incident as a potential hazmat safety concern and moved to a secured holding area. The local Toyota or Honda dealership should be notified of this incident and the request made for proper battery disposal to be completed by an authorized battery recycling agency.

What emergency procedures should be taken at a vehicle crash incident?

The following real-world incidents demonstrate potential challenges that may confront responders to hybrid vehicle crash scenes.

Incident 1. “The other car was traveling the wrong way in the oncoming lane. Insight driver swerved to avoid head-on collision, but was still hit broadside. Oncoming car traveling at estimated 45 mph.”

Incident 2. Sandwiched between Lincoln and parked cars. “Here are some photos of a recent accident. The Lincoln hit my parked Insight from behind and forced it into a Mazda and Civic in front of it. Estimates of his speed are around 30-35 mph. The inside cab area stayed pretty much intact.” — Peter Beargie

Incident 3. Insight sold for salvage on ebay.com. Details of what happened to this Insight are not available, other than that it was put up for sale under salvage title on the ebay.com website. The highest bid was $5,100.

General crash procedures can be developed for both the Toyota and the Honda hybrid vehicles. Although each is slightly different due to individual designs, the overall goals remain the same. These procedures represent hybrid vehicle ‘Lock Out-Tag Out’ protocols for emergency incidents that serve to maximize safety and minimize risks to personnel and patients.

First, we present an overview of the recommended vehicle crash procedures that are applicable to both hybrid vehicles:

• Hybrid vehicle identification.
• Vehicle stabilization.
• Access to the passenger compartment.
• Shift gear selector lever.
• Turn the key “OFF” and remove it from the ignition.
• Check that the green light goes out. On the Prius, if the key cannot be removed, responders can raise the hood and access the black plastic component labeled “IGCT” relay or the 20-amp HV fuse.
• Remove the IGCT Relay, or,
• Remove the HV fuse (20A).
• Disconnect the 12-volt battery.
• As a last resort, isolate the high-voltage battery pack. On the Toyota Prius, disconnect the orange service plug at the high-voltage battery pack. On the Honda Insight, it is also possible to turn off the Battery Module switch. This procedure is only recommended if the key cannot be turned off and the main fuse cannot be pulled.

Hybrid Vehicle Identification

What differentiates a conventional vehicle crash from one involving a hybrid vehicle begins with identification. Size-up of the scene must include efforts to view the entire rear of each crashed vehicle. This is the area of both hybrid vehicles that offers the only external indication that responders are dealing with a hybrid.

The Prius vehicle includes the words Prius Hybrid in chrome trim on the left of the trunk lid. The Honda Insight displays the Honda logo at the center of the hatchback and the Insight name to the right rear lip of the hatchback. The words gas-electric hybrid are visible along the left side of the hatchback.

The low-slung aerodynamic styling of the ultra-light Honda Insight also leaves little ground clearance. Quickly finding good stabilization points for placing stepchocks may be difficult. The vehicle may have to be lifted at the fenderwells in order to place cribbing under the vehicle.

Vehicle stabilization. Vehicle stabilization is important at any vehicle crash. In the case of a damaged hybrid vehicle, particularly one in “sleep” mode, stabilization efforts must immediately prevent any forward or rearward movement. Wheels must be blocked or chocked quickly to remove the possibility that the vehicle may suddenly “wake up” and lurch forward.

The Insight in the Auto Idle Stop mode will only start if the clutch is depressed and the transmission is shifted into gear. The Prius in the Ready mode will move forward if the pedal is depressed and the vehicle is in gear.

The Prius and the Insight both have independent MacPherson strut front suspension with a rear torsion beam and stabilizer bar. Both hybrid vehicles use narrow width tires. The Prius comes equipped with 14-inch tires on aluminum alloy wheels. The Prius has a ground clearance of only 4.9 inches under normal circumstances.

The low-slung aerodynamic styling of the ultra-light Honda Insight also leaves little ground clearance. Quickly finding good stabilization points for placing stepchocks may be difficult. The vehicle may have to be lifted at the fenderwells in order to place cribbing under the vehicle.

With access to the interior, the gear selector of the Prius must be moved into the ‘P’ or park position. If the selector cannot or will not move, there is a mechanical release button covered by a plastic panel along the bottom of the steering column housing. Remove this plastic cover and depress the red button. While pressing against this button, the selector lever can be moved upward to the “P” position. The gear selector of the Honda’s five-speed transmission must be moved to the “N” or neutral position to eliminate the possibility of the vehicle lurching forward accidentally.

In an actual crash scenario, the aluminum wheel may be fractured and the narrow tire may be deflated. Stepchocks may have to be turned upside down and used as a large wedge in order to fit under the vehicle. Actual wedge blocks may be most efficient for this purpose. In addition, the vehicle may have to be lifted manually at the wheelwells to allow stepchocks to be positioned underneath.

Access to the passenger compartment. After hybrid vehicle stabilization is accomplished, access must be gained to the passenger compartment. Scan the vehicle interior for airbags, remaining especially aware of the side impact airbags that may be present within the seatbacks of the Prius.

If a door opens, particularly the driver’s door, open it. If the door is jammed, access by taking out tempered glass must be accomplished. Responders must be able to reach the ignition key on the right side of the steering column. On the Prius, responders must be able to reach the gear selector lever on the dashboard. On the Honda, responders must be able to shift the manual transmission into neutral.

Move the gear shift selector. With access to the interior, the gear selector of the Prius must be moved into the “P” or park position. If the selector cannot or will not move, there is a mechanical release button covered by a plastic panel along the bottom of the steering column housing. Remove this plastic cover and depress the red button. While pressing against this button, the selector lever can be moved upward to the “P” position. The gear selector of the Honda’s five-speed transmission must be moved to the “N” or neutral position to eliminate the possibility of the vehicle lurching forward accidentally.

Turn ignition key to the “OFF” position and remove the key. With the vehicle physically stabilized to prevent movement and the gear selector set properly, responders can initiate a special hybrid vehicle ‘lock out/tag out’ process. Once the selector lever has been moved, the inside rescuer must turn the ignition key to the “OFF’ position. Once turned off, remove the key from the ignition.

Check that the green light goes out. As the ignition key is turned to the “OFF” position, the green indicator light on the dashboard of the Honda and the Toyota should go out. On the Toyota, the green light is the “READY” light found in the instrument cluster centered across the dash.

With the vehicle physically stabilized to prevent movement and the gear selector set properly, responders can initiate a special hybrid vehicle “lock out/tag out” process. Once the selector lever has been moved, the inside rescuer must turn the ignition key to the “OFF” position. Then, remove the key and let it be visible to assure responders that the engine is turned off.

On the Insight, the green light is within the instrument cluster directly in front of the steering wheel. The green LED light reads “AUTO STOP” and has a green diamond to the left of the “AUTO STOP” indicator. This indicator is at the left of the tachometer within the instrument cluster.

If rescue personnel are unable to move the Prius gear selector lever into the “PARK” position and are unable to move the ignition key to the “OFF” position, there are two backup plans that can be implemented for this vehicle.

Raise the hood of the Prius. About midway along the top of the firewall is a black plastic box. Remove the cover of this box. There are four electrical components inside. Remove the electrical relay on the far right (driver’s side). This relay is the IGCT Relay. Removing it breaks the power circuit from the high-voltage battery.

If for some unusual reason the Toyota Prius gear selector cannot be moved to park, the key cannot be moved to the “OFF” position and the IGCT Relay cannot be removed, there is a Plan “C.” With the hood open, locate the electrical fuse panel at the right (driver’s) side of the engine compartment. Remove its plastic cover. Locate and remove the 20-amp HV fuse within this fuse panel. HV means High Voltage. This fuse also shuts down power from the high-voltage battery.