Battery & Electrification Technology - May/June 2024 - 18

Battery Management
3
No Error
5% Error
1% Error
85 kWh
81.1 kWh
75.9 kWh
67.4 kWh
4
5
2
1
Figure 3: A more accurate State of Charge (SoC) increases usable battery capacity.
(Image: Teradyne)
while a BMS accuracy of +/-5 percent
gives limits of 15 percent and 85 percent,
and usable energy is 70 percent. Overall,
the lower the accuracy of the BMS, the
lower the usable energy. Figure 3 provides
a look at how accuracy increases usable
battery capacity.
This, coupled with emerging battery architectures
and chemistries and other vehicle
improvements, would enable automotive
manufacturers offering 300 miles
on a single battery charge today to offer
500 to 600 miles, a notable competitive
differentiator to attract hesitant buyers.
As battery packs become more densely
integrated and support higher voltages,
IC testing is essential for guaranteeing
device quality - both ensuring longevity
of EVs in the field and delivering differentiators
for new EV models. The test challenge
is to be more precise than the device,
by a factor of 10x or more.
Managing Complexity of
Testing Multiple Li-ion Battery
Technologies
While accurate measurement of an
EV's battery cells is vital to alleviating
range anxiety, the safety and reliability of
lithium-ion batteries in EVs are equally
important. Smaller and lighter than conventional
rechargeable battery technologies,
Li-ion devices deliver high energy
efficiency, high energy and power density,
and long life cycles.
Yet because Li-ion batteries can ignite,
it's crucial to thoroughly monitor
the storage and release of energy inside
the system's battery cells. A state-of-theart
BMS enables charge and discharge
cycles to be managed more safely, which
18
extends battery life and minimizes the
risk of catastrophic failure and fire.
Lithium batteries are dominating the
EV market space and are currently available
in a variety of chemistries, including
Nickel Manganese Cobalt (NMC) and
Lithium Iron Phosphate (LFP). Both options
have their advantages and disadvantages;
for example, NMC batteries are
susceptible to dangerous thermal runaway,
which can cause fires, while LFP
options may be adversely affected by very
cold temperatures.
Furthermore, the market is dynamic
with continuously changing cell chemistries.
There is a general shift away from
NMC and toward LFP, due to LFP's voltage
vs. state of charge curve being typically
flatter than that of NMC. A near-future
chemistry, Lithium Iron Manganese
Phosphate (LMFP), may bridge the gap
between the pros and cons of NMC and
LFP, but could require more complex test
and monitoring devices.
But what is the impact of multiple
technologies on the BMS sector? As battery
manufacturers face a widening array
of options, determining a battery's SoC is
becoming more challenging. Multiple
evolving technologies define this as a
dynamic market and BMS manufacturers
require a flexible ATE test solution to
handle the challenge and future-proof
their BMS investments.
In response to this need, the ATE industry
is delivering technology to support
temperature-stable, multi-channel instrumentation,
requiring less calibration
and offering higher throughput. Multichannel
ATE technology is optimized to
get precise measurements quickly.
1...Braking Protection: 3.9 kWh
2. Zero Mile Protection: 5.1 kWh
3. Range Charge: 8.5 kWh
4. Available for Range Driving
5. Available for Normal Driving
Usable Energy 80%
Usable Energy 70%
Usable Energy 78%
New Challenges for Battery
Management
As the EV industry continues to grow
and mature, battery voltage and architecture
changes manifest in the form of
higher battery capacity and the capability
for faster charging. The resulting
increase in cell count leads to larger
packages and higher voltage, creating
test challenges. As a capital expenditure,
test equipment must not only
meet current technological requirements
but also be future proof as technology
advances.
The anticipated exponential growth of
EVs requires higher throughput and economic
scalability for test. This growth is
predicated upon testing devices quickly
at automotive quality levels.
Voltages are now spiking upward, ranging
from 400V to 800V, which requires
increasingly more battery cells. This
steady stream of advancements means
automotive manufacturers must lean
harder on BMS innovation and functionality
to keep auto buyers satisfied with
their purchases. Potential buyers will always
care deeply about range and battery
health, considerations just as important
as automotive safety systems.
In any case, these requirements demand
more stringent testing. The semiconductor
ATE industry is rising to the
challenge, with advanced instrumentation
that supports more accurate testing
of higher voltage in the BMS. This includes
committing to future preparedness
by creating long-term product roadmaps
to support the throughput needed
for increasingly higher voltages.
Battery management systems are
poised to become a key competitive
differentiator in an EV market that is
seeking to grow and thrive on a global
level. And by tapping into smarter BMS,
automotive manufacturers are future-proofing
their resources by embracing,
even anticipating, trends in EV
battery design.
This article was written by Thomas
Koehler, Product Marketing Manager for
the Automotive and Complex Power
Device segment at Teradyne (North
Reading, MA). For more information, visit
www.teradyne.com/application-pages/
automotive/. 
Battery & Electrification Technology, May/June 2024
http://www.teradyne.com/application-pages/automotive/ http://www.teradyne.com/application-pages/automotive/
Battery & Electrification Technology - May/June 2024

Table of Contents for the Digital Edition of Battery & Electrification Technology - May/June 2024
