NFPA Journal - January/February 2020 - 32

101 remained closed for six hours as
Tesla employees removed the exposed
portion of the battery and isolated the
exposed high-voltage wiring, while
firefighters provided water as necessary to keep the fire from reigniting.
With about a quarter of the battery
removed, it was agreed that the car

p Top, the Tesla crash in Mountain View, California spread debris across a busy freeway,
including pieces of the EV's battery that were still energized. Below, engineers from the
nearby Tesla headquarters work at the crash site to de-energize portions of the battery.

32 | NFPA JOURNAL * J A N U A R Y / F E B R U A R Y 2 0 2 0

was safe to transport to an impound
yard in nearby San Mateo. A Mountain
View fire captain and fire truck accompanied the tow on the roughly 20-mile
trip. During the ride, what was left of
the car's battery continued to pop like
a firecracker.
At the impound, the vehicle's battery
ignited twice within the first 24 hours,
and the salvage yard operator had to
call San Mateo firefighters to assist.
The following Thursday, six days after
the initial crash, the battery reignited
yet again. Tesla engineers eventually
removed the remaining battery from
the vehicle and de-energized it by submerging it in a vat of salt water.
Afterward, the US National Transportation Safety Board investigator who
looked into the crash told Diaz that the
Mountain View department was the
first he had seen to properly mitigate a
battery fire under such extreme circumstances. Other than the driver of the
vehicle, no further injuries or damage
were reported.
Still, the crash-and dozens of others
like it around the world-lay bare the
gaps in our understanding of what can
occur in such incidents, and how far
responders have to go to prepare for
the rapid influx of battery technology
that experts say is fast approaching.
That technology goes beyond EVs to
include all manner of energy storage
systems (ESS), from utility-scaled ESS
arrays to consumer-sized ESS that
can be stored in a home's garage to
provide electrical power on demand
(see "Beyond EVs," facing page). Right
now, though, the hazards associated
with EVs are of primary concern to
many responders. With the number
of EVs on the roads expected to rise
dramatically-and with it, the number
of crashes and associated challenges-
emergency response experts say much
more research and training are needed
to provide them with tools to deal more
safely and effectively with the most
severe EV incidents.
The responding Mountain View
crews were out of service for about
seven hours for a single EV crash; a
similar accident involving a combustion engine vehicle would typically take
about 30-45 minutes to clear, Diaz said.

MOUNTAIN VIEW FIRE DEPARTMENT

About two hours into the event, a
team of Tesla engineers arrived at the
crash site, dispatched from company
headquarters just down the road.
The engineers began the laborious
task of disassembling the damaged
battery cell by cell, dropping each
into a bucket of water. The six-lane
NFPA Journal - January/February 2020

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