H2scan BSS Catalog 2025 - Flipbook - Page 30
Thermal Runaway / Thermal Walkway
Thermal Runaway is a self-sustaining and
uncontrollable rise in temperature resulting in a failure
of a cell, unit or battery. The thermal runaway event will
remain self- sustaining until the available energy within
the cell, unit or battery is depleted.
Thermal Walkaway is a process in a battery, driven
by an external current source, in which heat from
recombination is generated faster than it can be
dissipated, resulting in increased current flow,
increased recombination, overheating and possible
battery failure. Thermal walkaway can be stopped
by removing the charging source or reduction of the
Figure 6 Thermal Runway
Battery Room Incidents
Loss of Essential Facilities
In Los Angeles, CA, on March 15, 1994, a battery post ignited at a telephone exchange, leading to a significant
incident. The batteries involved were six strings of VRLA batteries wired in parallel. The ignition of hydrogen at
one battery post caused a chain reaction, resulting in the loss of 911, police, and fire communications for an
hour. Additionally, three workers suffered injuries from smoke inhalation.
Decommissioned Data Center Disaster
On March 20, 2001, a battery hydrogen ignition incident took place in
an Uninterruptible Power System (UPS) battery room that housed VLA
batteries. The explosion caused a 400 ft2 hole in the room and inflicted
severe damage on various parts of the building. Following the incident, the
company evacuated the facility but left the VLA batteries on float charge.
Although a hydrogen monitoring system connected to the ventilation system
raised an alarm when emergency responders arrived, it remained uncertain
if the ventilation system was operational or turned off when the building
was vacated. Three days before the explosion, 911 callers reported hearing
alarms, indicating a lack of connection to a fire panel. This local alarm setup
did not notify building management or the fire department of the situation.
Power Plant Thermal Runaway
In Milford, CT, on December 18, 2019, a battery fire broke out at the NRG power plant. The incident involved a
battery overheating within a 250 V DC battery bank comprising 50 lead acid batteries, leading to an electrical
fault and subsequent fire engulfing the battery bank. Firefighters successfully extinguished the flames using
a dry chemical fire extinguisher. Fortunately, there were no reported injuries or fatalities as a result of this
event.
Wind and Fire
An incident occurred on August 1, 2020, at a wind farm in Oahu involving
lead-acid energy storage batteries. The battery room contained 12,000 VRLA
lead acid batteries for capturing wind energy. Suspected thermal runaway led
to the batteries catching fire and burning for 13 hours, followed by smoldering
for another 36 hours, resulting in the complete loss of the building.
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