ABSTR ACT
Radiographic testing (RT) has become an essential
nondestructive evaluation method for electric
vehicle (EV) powertrain components, whose
delicate and encapsulated internal features cannot
be assessed through traditional tactile or optical
inspection. This paper reviews the current state of RT
technologies used for both production and research
applications, with emphasis on batteries and
motors—the most critical components unique to EV
platforms. Key topics include rapid in-line computed
tomography (CT) for battery cell quality assurance,
automated defect recognition (ADR) and artificial
intelligence for high-throughput data analysis, and
the specialized high-resolution CT systems required
for R&D and failure analysis. Challenges such
as achieving sufficient penetration, maintaining
resolution at high speeds, and imaging low-density
materials embedded within dense structures are
discussed, along with recent technological advances
that are enabling practical solutions. The paper
highlights how RT is evolving to meet the increasing
demands for performance, reliability, and yield in
modern EV manufacturing.
KEYWORDS: radiographic testing (RT), electric vehicle (EV)
batteries, computed tomography (CT), ADR
Introduction
The arrival of the electric vehicle (EV) as a priority in auto-
motive manufacturing has created a wide range of challenges.
Inspection technologies for components of internal combus-
tion (IC) vehicles have been developed to near perfection over
the last 130 years. These technologies have also benefited from
the fact that the main engine parts can easily be inspected
externally for fitness for purpose. Technologies ranging from
go/no-go gauges to coordinate measuring machines (CMMs)
and white-light and laser scanners are fully capable of external
inspection. Nondestructive inspection for internal features
exists but is used for only a small number of applications, such
as safety-critical castings, where it is important to check for
porosity—specifically in engine blocks. In addition to looking
for porosity, critical internal features such as oil and water
channels also require inspection.
Contrast this with EV powertrain components, where
almost every critical part is delicate in nature and encap-
sulated, and out of the reach of tactile and optical inspec-
tion. Inspection of these components requires radiographic
testing (RT).
Of the components that are not shared with IC vehicles, the
most obvious and critical are the EV batteries and the motors.
Batteries
The “battery” in an EV is an all-encompassing term for a
system of electrical energy storage consisting of many parts
that together form a “battery pack” with its own control
and cooling systems. This battery pack, in turn, consists of
“modules,” which also have a control system and often their
own cooling system. These modules are composed of battery
cells, which may be the familiar “cylindrical cells,” “prismatic
cells,” or “pouch cells.” All perform the same role and contain
layers of anode and cathode elements arranged in different
configurations (see Figure 1).
What all these components have in common is that they
contain very delicate parts, and they are sealed, making them
impossible to inspect by optical or tactile means from the
outside.
X-ray technologies are the only viable solution for inspect-
ing batteries without taking them apart. There are two main
areas where X-ray inspection is currently used: production for
battery quality assurance (QA), and research and development
(R&D) for development and failure analysis.
USES OF RADIOGRAPHIC TESTING FOR NDT
ON EV POWERTRAIN COMPONENTS
GILES GASKELL†, NEIL BLOOMFIELD‡, DANIEL SHEDLOCK§, AND EMIL ESPES††
† Pinnacle X-Ray Solutions, Duluth, GA, USA ggaskell@pxsinc.com
‡ Waygate Technologies, Cincinnati, OH, USA
§ Varex Imaging, Franklin Park, IL, USA
†† Excillum AB, Kista, Stockholm, Sweden
Materials Evaluation 84 (1): 54–60
https://doi.org/10.32548/2026.me-04547
©2026 American Society for Nondestructive Testing
ME
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M AT E R I A L S E V A L U AT I O N • J A N U A R Y 2 0 2 6

Production Inspection for QA
There are two primary reasons why production inspection of
batteries is crucial. If a bad battery cell is undetected and ends
up in a finished battery pack, that battery pack and hence the
whole vehicle’s performance can be adversely affected, and
worse still, might be a safety risk. Another reason is that by
identifying and isolating defective cells, the cause of the defect
can be determined, and adjustments can be made to the pro-
duction process to reduce scrap rates.
BATTERY CELLS
The comparison of scrap rates for EV batteries during man-
ufacturing with those of IC engine components is stark. Over
the years, production processes for manufacturing IC compo-
nents such as pistons, crankshafts, engine blocks, and valves
have become so refined that, compared with the numbers for
EV batteries, their rejection rates can be considered almost
negligible.
According to a report by the Fraunhofer Institute, new
battery production lines often see scrap rates of 15–30%, and
even five years after the start of production, scrap rates still
average around 10% [1]. In-line, 100% inspection using RT has
so far proven to be the only technology capable of penetrat-
ing the outer enclosure of the battery and nondestructively
measuring the delicate internal components, thereby ensuring
that noncompliant batteries are not placed into service.
Fortunately, although 100% inspection of batteries is
required to ensure no failures are missed, it is not necessary
for 100% of the battery cells to be inspected to determine
whether they are likely to be faulty. The reason is that the over-
whelming majority of failures in newly manufactured battery
cells are due to one cause: misalignment of the anode and
cathode layers within the cells. This condition can be detected
with X-ray computed tomography (CT) by scanning a limited
region of interest (ROI) rather than the whole battery. To detect
problems with battery components, the scan resolution needs
to be as small as 20–30 µm, which is only possible when the
ROI is small. As the size of the CT ROI increases, the resolu-
tion of the resulting scan becomes correspondingly coarser,
making clear imaging of delicate components impossible (see
Figure 2).
ANODE CATHODE ALIGNMENT
There are three main types of battery cells used in EVs: cylin-
drical cells, prismatic cells, and pouch cells. In all of these,
the main cause of failure is misalignment of the anodes and
cathodes.
Figures 3 and 4 display 2D slices from a 3D image created
by a CT scanner. CT scanning provides full 3D definition of
the object, enabling it to be fully inspected, unlike digital
Battery cell
Battery module
Battery pack
Figure 1. The basic components of an electric vehicle (EV) battery pack:
the modules and individual cells.
Figure 2. The X-ray source, battery cell, and detector demonstrating
magnification of the region of interest (ROI).
Figure 3. 2D slice through 3D CT scan of even pouch cell anode
and cathode layer alignment. Voltage: 180 kV 80 µm focal spot
magnification: 4 × 100 µm detector pixel pitch 200 fps.
Figure 4. 2D slice through 3D CT scan of uneven anode and cathode
layer alignment, showing a damaged electrode likely to cause failure.
Voltage: 200 kV power at target: 10.8 W voxel size: 5 µm scan time:
2 h, 40 min focus-detector distance (FDD): 801 mm magnification:
19.5 × 4800 projections.
J A N U A R Y 2 0 2 6 • M AT E R I A L S E V A L U AT I O N 55
CREDIT:
WAYGATE
TECHNOLOGIES
CREDIT:
VAREX
IMAGING
CREDIT:
VAREX IMAGING
CREDIT:
WAYGATE TECHNOLOGIES