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Plugged into Safety: A primer on the hazards of working with battery electric vehicles | March 2024
BEV fires are very rare, but the severity of fires can be catastrophic.
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After a collision, it can take anywhere from minutes to days for a thermal
runaway event to occur.
It is more difficult to extinguish a battery fire than it is a gas-powered
engine fire. They combust differently and can take up to 40 times more
water to extinguish.
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Electrical Hazards
The electrical system of an electric vehicle is complex and involves high-voltage
components, which pose several hazards.
High-voltage – The battery pack in an EV is composed of several cells grouped
into modules. The number varies depending on the vehicle. Battery packs usually
operate at a high-voltage between 300-800 volts, and in some cases, even higher.
Contact with high-voltage parts of the battery can result in severe injury and
even death.
Energy stored in the battery – EV batteries store a large amount of energy that
can be disconnected from the drivetrain and other high-voltage systems, but
cannot be dissipated, which can cause electrical shocks or arcing when working
on or in the battery system.
Arc flash and arc blast – This occurs when there is a rapid release of electrical
energy due to a short circuit or other fault and can cause severe burns and injuries.
Capacitor discharge – Capacitors can retain charge, for a period of time, even after
the battery is disconnected. This stored energy can cause unexpected shocks.
" In ICE vehicles, the
hazards are well-
established and well-
known. If you see an
ICE vehicle running, you
know it is a dangerous,
fast-moving, loud,
metal object, and
there is a risk. EVs
aren't inherently more
dangerous; the dangers
are just different. With
EVs, the safety systems
are opaque, and there
is no way of knowing
about the hazards
before you're
in danger."
— Eric Ellis
Program Coordinator
and Professor,
St. Clair College
