SAE Update - July 2024 - 41

STANDARDS &
COMMITTEES
functional requirements like IPX7 into in-line, nondestructive
leak test requirements. The equivalent
channel represents the maximum allowed leak path
geometry; it can be reproduced and used during
functional and production verification of leak test
systems used in a production line.
Given the diverse designs of battery packs in terms
of size, material, and electrical systems, a one-sizefits-all
EC is not feasible. Instead, the EC method, per
SAE J3277, offers a production leak tightness
specification that can be tailored to individual battery
pack designs. Properly applying the EC leak tightness
requirement per SAE J3277 should replace the water
immersion test with similar or better results.
SAE J3277 addresses two leak tightness cases: (1)
water IP into the battery pack, using IPX7 as an
example, and (2) coolant leakage from the battery
pack cooling system into its headspace.
Two approaches are offered for water IP. The first
one, based on IEC 60529, allows minimal water ingress
(just a few drops) within 30 minutes as agreed
between the OEM and supplier. The second approach is
more conservative and requires zero water ingress
within 30 minutes, as per ISO 6469-1. In either case, the
coolant leak tightness requirement is " no sustainable
leakage of coolant into the battery pack headspace. "
The EC size ranges are estimated using the
analytical tools provided in SAE J3277, followed by an
empirical test, per the guideline and example in the
document. The final EC (diameter and length) is
established based on the empirical test. Once EC
geometry is defined, proper air or tracer gas flow
versus pressure curves can be developed and used as
a threshold during production leak testing.
SAE J3277 is a precursor to SAE J3277/1, a work-inprogress
which will present the practices to qualify
UPDATE
The two leak tightness cases addressed in SAE
J3277 can help prevent water-induced battery
fires in electric vehicles.
that product leak tightness is
equal or better than the
maximum allowed EC for that
product using applicable and
commercially available leak test
technologies.
By adopting SAE J3277 and its
associated practices, we can
elevate the standard of EV
battery pack safety and
performance, mitigating
incidents like those experienced
during recent hurricanes. n
ABOUT THE AUTHOR:
Hemi Sagi is a leak-testing expert with four
decades of automotive industry experience.
In addition to serving as the document
sponsor for SAE J3277 and SAE J3277-1, he
has served as a technical editor and
reviewer for SAE journals. His company,
Advanced Test Concepts, Inc., helped to
introduce the equivalent channel concept as
a means to specify leak tightness.
July 2024
41
Palm Habor Fire Rescue
https://www.sae.org/standards/content/j3277/1/
SAE Update - July 2024

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