2
emergencies [8]. Mine rescue robots and drones offer the
potential to provide supply, surveillance, and sensing capa-
bilities that are critical for search and rescue operations.
Ali [9] identified several attempts to develop mine rescue
robots. Ali indicated that several rescue robots are currently
being developed, and a few have been tested in real-world
circumstances, albeit with unsatisfactory outcomes. Ali
asserted that the challenge for the industry is to make more
advanced, smarter rescue robots with strong and reliable
hardware to work in dangerous zones.
Dubaniewicz et al. [10] reported that Li-ion battery
thermal runaway may produce excessive pressures within
sealed enclosures that provide relatively little free space
around the battery. Results of that work support consid-
eration for revision of safety standards, such as the IEC
60079-1 edition 8 Equipment protection by flameproof
enclosures “d”, because the standard does not provide assess-
ment criteria for Li-ion battery thermal runaway failure
modes. The work also suggests that, where battery enclo-
sure internal volume restrictions may prevent adequate free
space, thermal runaway cascade prevention and venting
with properly designed and maintained flame arrestors are
potential mitigation strategies for excessive overpressures.
XP enclosures typically include a cover with a flame
quenching joint, cable entrance, and may include an auxil-
iary pressure-relief device. The maximum internal pressure
during the ignition of an explosive air mixture in an enclo-
sure is directly related to the amount of venting through
flame quenching gaps and auxiliary pressure-relief devices
[11]. This raises the question as to whether the flame
quenching gaps of conventional XP enclosures provide suf-
ficient pressure relief and quench a Li-ion battery thermal
runaway, without the need for an auxiliary pressure-relief
device. In this work, researchers at the National Institute
for Occupational Safety and Health (NIOSH), Pittsburgh
Mining Research Division (PMRD), initiated a Li-ion bat-
tery thermal runaway within a modified commercial XP
enclosure to see if venting through the cover joint and leak-
age through the cable entrance provided sufficient pressure
relief while preventing excessively hot gasses from escaping.
MATERIALS AND METHODS
Figures 1, 2, and 3 show the battery pack and XP enclo-
sure. The battery pack consisted of thirty-nine model MH1
Nickel Manganese Cobalt (NMC) 811 18650 cells arranged
in a 13 series by 3 parallel configuration. The MH1 cell
ratings were 3.2 Ah, 3.67 V, and 11.7 Wh. A multichan-
nel potentiostat/galvanostat (MSTAT, Arbin Instruments,
College Station, Texas) cycled the cells using cell-manufac-
turer-specified parameters. The cells were conditioned with
three charge-discharge cycles followed by a charge to 100%
state of charge. The battery voltage at the start of the test
was 53.7 V. Table 1 lists the battery electrical parameters.
A 240 W disk heater was placed on top of the battery pack
to initiate thermal runaway. The disk heater contacted mul-
tiple cells to simulate heating such as from external short
circuits. Disk heater activation marked the start of the test.
The XP enclosure’s specified dimensions were approxi-
mately 10.375 inches (16.4 cm) in length by 7.375 inches
(18.7 cm) in width by 6.156 inches (15.6 cm) in depth
(less cover). The enclosure was made from welded steel with
a 0.507-inch (1.29-cm) thick flat aluminum cover bolted
to the enclosure. The enclosure walls were approximately
Figure 1. Battery pack with disk heater on top. Arrows point
towards thermocouple locations out of view
Figure 2. Battery pack placed within XP enclosure
emergencies [8]. Mine rescue robots and drones offer the
potential to provide supply, surveillance, and sensing capa-
bilities that are critical for search and rescue operations.
Ali [9] identified several attempts to develop mine rescue
robots. Ali indicated that several rescue robots are currently
being developed, and a few have been tested in real-world
circumstances, albeit with unsatisfactory outcomes. Ali
asserted that the challenge for the industry is to make more
advanced, smarter rescue robots with strong and reliable
hardware to work in dangerous zones.
Dubaniewicz et al. [10] reported that Li-ion battery
thermal runaway may produce excessive pressures within
sealed enclosures that provide relatively little free space
around the battery. Results of that work support consid-
eration for revision of safety standards, such as the IEC
60079-1 edition 8 Equipment protection by flameproof
enclosures “d”, because the standard does not provide assess-
ment criteria for Li-ion battery thermal runaway failure
modes. The work also suggests that, where battery enclo-
sure internal volume restrictions may prevent adequate free
space, thermal runaway cascade prevention and venting
with properly designed and maintained flame arrestors are
potential mitigation strategies for excessive overpressures.
XP enclosures typically include a cover with a flame
quenching joint, cable entrance, and may include an auxil-
iary pressure-relief device. The maximum internal pressure
during the ignition of an explosive air mixture in an enclo-
sure is directly related to the amount of venting through
flame quenching gaps and auxiliary pressure-relief devices
[11]. This raises the question as to whether the flame
quenching gaps of conventional XP enclosures provide suf-
ficient pressure relief and quench a Li-ion battery thermal
runaway, without the need for an auxiliary pressure-relief
device. In this work, researchers at the National Institute
for Occupational Safety and Health (NIOSH), Pittsburgh
Mining Research Division (PMRD), initiated a Li-ion bat-
tery thermal runaway within a modified commercial XP
enclosure to see if venting through the cover joint and leak-
age through the cable entrance provided sufficient pressure
relief while preventing excessively hot gasses from escaping.
MATERIALS AND METHODS
Figures 1, 2, and 3 show the battery pack and XP enclo-
sure. The battery pack consisted of thirty-nine model MH1
Nickel Manganese Cobalt (NMC) 811 18650 cells arranged
in a 13 series by 3 parallel configuration. The MH1 cell
ratings were 3.2 Ah, 3.67 V, and 11.7 Wh. A multichan-
nel potentiostat/galvanostat (MSTAT, Arbin Instruments,
College Station, Texas) cycled the cells using cell-manufac-
turer-specified parameters. The cells were conditioned with
three charge-discharge cycles followed by a charge to 100%
state of charge. The battery voltage at the start of the test
was 53.7 V. Table 1 lists the battery electrical parameters.
A 240 W disk heater was placed on top of the battery pack
to initiate thermal runaway. The disk heater contacted mul-
tiple cells to simulate heating such as from external short
circuits. Disk heater activation marked the start of the test.
The XP enclosure’s specified dimensions were approxi-
mately 10.375 inches (16.4 cm) in length by 7.375 inches
(18.7 cm) in width by 6.156 inches (15.6 cm) in depth
(less cover). The enclosure was made from welded steel with
a 0.507-inch (1.29-cm) thick flat aluminum cover bolted
to the enclosure. The enclosure walls were approximately
Figure 1. Battery pack with disk heater on top. Arrows point
towards thermocouple locations out of view
Figure 2. Battery pack placed within XP enclosure