New electric vehicles in the United States and Canada are about to go through a hugely important charging revolution starting this year, as the transition from the Combined Charging System (CCS) to the North American Charging Standard (NACS) gets under way. Practically every OEM that sells EVs in the U.S. today is promising it will update its charging ports from CCS to NACS in due time, but doing so is a lot more involved than simply yanking out one port and swapping in the other.
The first vehicle on sale to make the switch from CCS to NACS is the refreshed 2025 Hyundai Ioniq 5, a car we drove just a short couple of weeks ago. So, how'd Hyundai do it? We sat down with battery guru Karl Holodnick, Hyundai engineering manager for propulsion and charging, to talk it out.
"I would say probably the biggest change is, you now have, going from CCS to NACS, consolidated the AC and DC lines at the charging port," Holodnick tells Road & Track, "where before you had separate charging lines for the DC and AC lines."
Lost already? That's okay. Seeing a diagram of the different connector designs helps.
The CCS connector has separate pins for alternating-current and direct-current charging: The top portion of the plug is used for AC, while the bottom comprises the additional two DC power lines. You may have already deduced this if you've ever plugged a non-Tesla EV into a Level 2 charger; the bottom part of the CCS connector is missing, because the only goal is taking on AC power.
However, whether you're plugging into a Level 2 AC charger or a Tesla Supercharger (a DC fast-charger), there is no difference in the connector design for Teslas. This means the car needs to know what kind of charger you're using before charging begins, for safety's sake.
"So probably the biggest change that we've made to the design and switching over is the addition of a relay in the system, because you're using the same cables for AC and DC," Holodnick says. "We added the relay to the system in order to switch from both alternating current to direct current. You can imagine that if both lines are active at the same time, you're damaging components."
In addition to the physical relay, Hyundai needed to implement new code to work with it. "It's not only the hardware change that we've made, but we've also added new safety related software functions to the system as well," Holodnick says. "If we're DC charging, one of the first things that we do in the initialization process is checking to make sure that the AC line is open before we send the DC power to the battery and vice versa."
Getting the software right and making sure charging is a seamless experience for customers required a lot of collaboration with Tesla. It's a relationship Holodnick speaks highly of, as successfully working with those folks is one of the factors Hyundai credits with it being first to market with its NACS transition.
"One of the keys there is probably open communication with Tesla," Holodnick says. "We built a pretty good working relationship with them to, you know, get all of the development work done to make it happen. In terms of the modifications that we made to our system, it's been, I would say, overall a pretty smooth and seamless transition."
The key matter that Hyundai and Tesla worked on concerns the power-line communications (PLC) protocol. In layman's terms, this standardized protocol is what allows communication and coordination between the vehicle and the charging network. (Thankfully, NACS and CCS utilize the same protocol, easing this process.)
"During the PLC communication stage of the charging sequence, there is information that is shared back and forth between the vehicle and the charger," Holodnick says. "The vehicle has unique identifiers, the charger has unique identifiers, [and those] are shared in order to initiate the charging session. So there was a lot of work back and forth with Tesla to make sure that the vehicle and charger were communicating properly."
Getting this correct from the beginning is key for Hyundai, and it's something Holodnick and the team realize. A complaint that comes up repeatedly with CCS chargers is their tendency to underperform on claimed charge speed or simply be inoperable—Superchargers, meanwhile, have a much better reputation for consistent performance. Unfortunately, we're not totally out of the woods yet; peak charge speed remains a current-day compromise for many vehicles that'll make the NACS transition, and it's all to do with the electrical architecture of certain EVs.
Hyundai's E-GMP platform is an 800-volt system, and when plugged into a charger that can match its voltage (such as an Electrify America 350-kW fast-charger), the 2025 Ioniq 5 can charge at up to 257 kW. That gets you from 10–80% in only 20 minutes. Meanwhile, Tesla's Superchargers are 470-volt chargers, meaning the Ioniq 5's charge speed is ultimately limited by the power of the plug. Hyundai claims a max charge speed of 135 kW on Tesla's V3 Superchargers, which nets a 10–80% charge in 30 minutes. Holodnick adds that if/when Tesla rolls out its proposed 800-volt Superchargers, it will be able to charge with much greater power. Expect to see similar compromises in maximum charge speed with other EVs that don't match the voltage of Tesla Supercharger systems.
If you were expecting to hear about massive changes to the battery pack, electric motors, or other powertrain bits with the NACS transition, Hyundai's 2025 refresh does tweak the software and battery chemistry in order to facilitate faster charging on Superchargers. The chemistry changes help promote faster charging on non-Tesla chargers, as well, with the peak rate seeing a slight bump this year. Tweaks like those Hyundai made are things that other OEMs could very well attack differently, too, most likely in a similar effort to improve performance on Superchargers.
From the official NACS announcement to the start of North American production at the end of 2024, it took Hyundai just a year and a few days to finally drive an NACS Ioniq 5 off the assembly line. That's shockingly quick for any automotive change, let alone one as vital to a car's operation as EV charging. We're sure there will be refinements and user-experience improvements in time, but the big hurdle has been conquered: 2025 Ioniq 5s can mosey on down to a Tesla Supercharger and plug right in.
"If I can brag about my team a little bit," Holodnick says. "The hard work that the team has put into, you know, all of the performance testing; all of the interoperability testing; the long hours; and blood, sweat, and tears that they've really put into making sure that everything is working perfectly to get this right, in order to ensure a smooth launch. I think that's probably the thing that I'm most proud of."