Hybrid shutdown; Plan A, Plan B, and even Plan C

Blog Post created by andrewklock Employee on Oct 23, 2012

Untitled-1Example of a training scenario involving a collision between a hybrid vehicle and an internal combustion engine vehicle.  Crash-damaged hybrid and electric plug-in vehicles require additional training on proper vehicle shutdown procedures.

"The scene was nothing unusual" the Captain explained.  "The hybrid crashed into the side of the other vehicle.  Most of the damage to the Prius was on the front left corner" he said. "My ambulance crew made patient contact with both drivers and determined that there were no injuries. They were busy filling out the patient refusal forms."

What happened next was unusual for this experienced fire/rescue officer; an interesting twist that this real world incident from Pennsylvania took.  As the Captain was conducting his walk-around scene survey, he came close to the passenger side of the hybrid and suddenly stopped.  Puzzled by a sound
he heard coming from the engine compartment area, he shouted across the car to the driver, “I thought you said you turned the ignition off?”  The reply from the vehicle’s owner, ‘I did!’ was not what he expected.  Puzzled by a sound that resembled “a cooling fan hitting something“, he walked around the rear of the hybrid.  Just as he came around the car, the wiper on the rear hatchback glass operated back and forth one cycle. “This thing is still hot” he thought.

With the driver’s door open, he could clearly see that the dash-mounted POWER button was in the OFF condition; the small LED light was out.  The driver had pushed it once to shutdown the ignition as she stated.  As he glanced across the instrument panel however, he noticed all the gauges and dials were still lit and functioning.  Even the large screen in the center of the dash had a display on it.  Just at that time, the rear wiper made another pass across the hatchback glass.

“I applied the emergency brake and ordered the engine crew to work from the side to see if they could open the hood.”  At that time, realizing that an energized hybrid can unexpectedly move forward, he also had the engine company driver grab two wheel chocks and place them on the front drive wheels to prevent any movement.  The Captain went on to say “I told the firefighters to plan on shutting down the electric system.   I wanted this thing to go dark once and for all!”

What makes this case study so intriguing is that when additional units arrived, it was easy for them to access the hatchback area and uncover the 12volt battery.  Through training on electric and hybrid
vehicles, the Captain knew that the battery they were looking for would either be in the front engine compartment area or in the trunk.  Since this was a crash-damaged Toyota Prius, the Captain directed the second crew to attack the rear of the hybrid.

With relief that the 12volt battery was so quickly located in the rear wheelwell, the Captain felt that shutting this car down was just two cuts away.  To his disbelief, when the firefighter double cut the black ground cable to the 12volt battery and then even removed the positive cable, the noise in the front continued as well as the wiper kept up its regular pace of wiping across the hatchback glass.  Sure enough, his glance in through the driver’s door confirmed that even the instrument panel and all interior dash lights were still illuminated.  “How could that be?” he thought.  “The battery is completely disconnected.”

Perplexed, but not giving up, the Captain remembered that in training and in some of the hybrid and electric emergency response guides he had looked at, there was mention of some sort of fuses that could be used in an extreme situation. The challenge of shutting down this hybrid clearly was one of those ‘extreme’ situations to this crew and officer.  Frustration was mounting and the risk to everyone on scene was clearly evident.

Working from the side, the hood hinges were cut and the hood opened forward.  No one had to stand in front of the energized hybrid even though the front drive wheels were chocked and the parking brake set ‘ON’.  No sense of increasing the risk to his crew, he thought to himself.

The fuses in the engine compartment of this 2nd generation Prius are clearly
visible once the plastic fuse panel cover is removed.

With the engine compartment components now visible, the Captain started to pull, “all the relays and fuses I could see!” To his relief, once all the large fuses in the engine compartment were removed, the noise stopped and the vehicle did shut down. 

In NFPA’s Electric Vehicle Safety Training project, information about shutting down a crash-damaged hybrid or electric plug-in vehicle is presented.  The training, which is now available online as well as in-person through state fire academies, provides every emergency response guide produced by the car manufacturers and explains steps for turning off the ignition and shutting down the 12volt electric power by disconnection or cutting 12volt battery cables. This detail is also included in the latest version of NFPA’s EV Emergency Field Guide. In a situation such as this case study, where doing the right thing still did not give the desired results, knowing about pulling fuses was critical.  Pulling fuses on hybrids or electric plug-ins is not something that a responder would normally think of. 

We don’t pull fuses at our routine crash incidents involving conventional vehicles so we do not think about this special procedure.  With a crash incident involving a hybrid or electric plug-in however, knowing about this alternative; one of our newest back-up plans for hybrid and electric vehicle power shutdown, may be a life saver. 

The fuse panel of this crash-damaged hybrid is exposed.  Although not normally necessary, responders should be trained and prepared to remove fuses as one means of shutting down an energized hybrid or electric plug-in vehicle

Visit to review training materials provided by automakers, participate in the online electric vehicle training, sign up for an online EV Safety blog, and access additional training resources from the NFPA.

Ron Moore, NFPA Fire Service Training Consultant