Automotive Engineering - December 2024 - 10

TECHNOLOGY REPORT
The SAE booth at
Battery Show North
America 2024 in
Detroit.
Rodney McGee, director of the NACS J3400
Task Force and an electrical engineering
professor at the University of Delaware.
charge at the gold-standard Tesla network,
other operators will need to
match Tesla in ease-of-use and reliability
or they'll lose the apples-to-apples
comparisons that EV drivers will make
in a way they couldn't before. Second,
the reason Tesla's network has advantages
over the OEM-and-supplier-built
networks that non-Tesla drivers deal
with is that Tesla engineers worked on
both the vehicle and the EVSEs.
" When [Tesla] designed the basis of
NACS over ten years ago, they were
always focused on both sides, " McGee
said. " They were a company building
and operating a charging network and
10 December 2024
also building cars, and when you approach
a system from that development,
you end up maybe in a different
place than when J1772 was started,
when OEMs did not have these energy
units and these huge investments in
infrastructure. Now, they're on both
sides of the equation and so the system
design of NACS really is about mass
electrification: having a connector that
can support more voltage types for AC
charging and more connection methods.
We really brought in a lot of that
stuff to be THE standard to electrify
transportation in North America, especially
for passenger cars. "
Compared to J1772, for example,
J3400 will allow for digital communication
between the car and the charger
(J1772 uses what McGee called a " very
dumb analog communication method " )
and the task force hopes to bring features
like minimum required error codes
that the ChargeX consortium uses with
DC fast charging to the new AC J3400
standard. J3400 also adopts V2G and
backup power requirements.
J3400 will also update the North
American charging landscape to allow
for carry-along cord sets, McGee said.
Common in the rest of the world, personal
cords allow for smaller, cheaper
EVSEs because the stations offer a
standard port instead of a cable and
plug that requires more investment
and maintenance. This will help bring
EV charging infrastructure to lowerincome
drivers and people who live in
apartments.
" The stuff that hangs around when
there's no electric car there needs to be
minimized, " McGee said. " It needs to
disappear into the infrastructure. And
that'll really drive curbside charging. "
The J3400 RP currently says the
maximum amperage for the standard
would be 900 amps if it's just cooling
from the connector side and 1000 amps
if cooling from both the vehicle inlet
side and the connector side. " [That] is
just theoretical, " McGee said, since no
automaker has announced anything
that powerful. " But in theory, NACS
tops off at exactly one megawatt. "
On the voltage side, the updated
NACS will bring some of Tesla's farsightedness
to the broader public. Tesla
chargers are able to use the 480-volt,
three-phase power that comes from
utilities to a commercial site as singleplace
power at 277 volts and put that
into the vehicle directly, McGee said.
That will mean cheaper AC charging
because you don't need to have to pay
for an extra transformer right there on
the curb. Using less copper and a smaller
conduit are other benefits.
Sebastian Blanco
AUTOMOTIVE ENGINEERING
FROM TOP: CHRIS CLONTS; SEBASTIAN BLANCO
Automotive Engineering - December 2024

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