DC Fast Charging Demystified: CCS vs. NACS for EV Builders

Understanding DC Fast Charging with CCS and NACS

As the EV market matures and fast-charging infrastructure expands, a new frontier is opening up, not just for automakers and networks, but for builders and tinkerers too. Whether you’re crafting a one-off electric restomod or planning a high-voltage swap, understanding the DC fast charging landscape is becoming increasingly important.

The J1772 plug, or “J-plug” has long been the industry standard for AC charging ian North America.

In a previous EV Builder’s Guide article, we covered the fundamentals of AC charging, including Type 1 (J1772) and Type 2 connectors. This time, we’re zooming in on DC fast charging: what it is, how it works, and what you need to know if you’re planning to integrate it into your build.

A Quick Refresher: Type 1 and Type 2 Charging

Before diving into DC fast charging, it’s worth revisiting the basics.

While finding a charging station for a J1772-equipped vehicle is straightforward, power is limited at 19.2kW max.

Type 1 (J1772) is the standard AC plug used in North America for Level 1 and Level 2 charging. It’s common for EV conversions and daily use, capable of delivering up to 19.2 kW in Level 2 setups.
Type 2 (Mennekes) is Europe’s AC standard and supports both single- and three-phase charging. While not commonly used in U.S. builds, it’s helpful to know if you’re importing components or vehicles.

Level 1 vs. Level 2: What’s the Difference?

Level 1 charging uses a standard 120V household outlet and delivers around 1.4 kW of power. It’s slow—often adding just 3–5 miles of range per hour—but it works in a pinch or for overnight charging.
Level 2 charging uses 240V (like a dryer outlet) and can deliver anywhere from 3.3 kW to 19.2 kW, depending on your EV’s onboard charger and the charging station. This is the most common setup for home garages, shops, and public AC charging stations.

An onboard charger, such as the AEM CCU, is installed in the vehicle and is responsible for converting grid power to DC power to charge the batteries.

Both Level 1 and Level 2 charging go through the vehicle’s onboard charger, which converts AC from the wall into DC to feed the high-voltage battery. That onboard charger’s capacity and available grid power ultimately limit how fast you can charge using AC power.

If you want to break past those limits, you’ll need to step into the world of DC fast charging.

What Makes DC Fast Charging Different?

DC fast chargers skip the onboard AC-to-DC conversion. Instead, they deliver high-voltage DC power directly to the battery, dramatically increasing charge speed. But to make that happen, your EV needs:

Even vehicles equipped with fast charging will likely still come equipped with some kind of onboard charger for Level 1 & Level 2 charging duties.

A high-voltage battery pack (typically 200V and up)
A compatible DC charge port (either CCS or NACS)
A charge management controller to safely communicate with the charger and regulate the charge session

CCS ports are becoming increasingly common on aftermarket EV builds, like this one hidden behind the fuel door of a Porsche conversion.

Because fast chargers do the heavy electrical lifting, the vehicle’s onboard charger is bypassed entirely during DC charging. That means builds without DC integration simply won’t be able to take advantage of these speeds.

CCS: The Workhorse of Fast Charging

The Combined Charging System (CCS) is built on top of the J1772 connector, with two added DC pins. It’s been the go-to standard for most non-Tesla EVs in North America and Europe.

A CCS cable includes a J1772 for level 1 and level 2 charging, as well as dedicated cables for high-voltage DC power.

CCS1 is the North American variant
CCS2 is used internationally

CCS supports charging rates up to 350 kW (depending on the station and vehicle) and is widely available at networks like Electrify America, EVgo, and ChargePoint.

Pros:

Compatible with many production EVs
Backward-compatible with J1772 Level 2 charging
Supported by most public fast chargers

Cons:

Bulky connector design
Communication and integration challenges for DIY builds

NACS: Tesla’s Slim, High-Speed Standard

Tesla’s once-proprietary plug has now become the North American Charging Standard (NACS). It combines AC and DC charging into one streamlined connector and is rapidly being adopted by legacy automakers and charging networks.

A dedicated wire for every type of connection (DC, AC, and control wiring) requires a bulky connector.

NACS supports fast charging at Tesla Superchargers (up to 250kW currently) and is engineered for future scalability up to 1 MW.

Pros:

Sleek, compact design
Combined AC/DC functionality in one port
Backed by Tesla’s vast Supercharger network

Cons:

Still early in public rollout
Limited availability of open-source components for integration

Understanding Power: Why kW and Voltage Matter

Charging speed depends on power output, measured in kilowatts (kW). Power is the product of voltage and current (amps).

For example, typical 400V EV charging at 125A is charging at 60kW.

Revealed at SEMA, the Fellten NACS port offers a way to retrofit an EV to the new North American standard.

A larger battery doesn’t necessarily charge faster—it simply takes longer to fill, much like a bigger fuel tank. Here’s how it plays out:

Keep in mind: fast charging speeds taper off as the battery approaches full to preserve longevity.

The Reality Check: What It Takes to Add DC Fast Charging

While the benefits of fast charging are obvious, integrating it into a build comes with real-world hurdles:

CCS ports and fast-charging capabilities are becoming more common place in EV conversions.

High System Voltage

Most DC fast charging requires a minimum battery voltage of 200V—many OEMs use 350–800V systems to enable higher-speed charging. Low-voltage EV builds (under 144V) can’t take advantage of DC fast charging.

Expensive Hardware

Commercial DC fast chargers cost anywhere from $10,000 to $100,000+, and even small-scale DC charging units (25–50kW) are still a major investment for home or shop use.

Additional Components

To charge via CCS or NACS, your vehicle will need:

A DC charge port

A charge control module or CMC

CAN integration with your BMS to manage safety and state-of-charge communication

Proper high-voltage contactors, fuses, and interlocks

All this adds complexity and cost—especially when working outside the ecosystem of a production EV.

So, Should You Add DC Fast Charging?

For most EV builds today, Level 2 AC charging remains the most practical and cost-effective solution. It’s simple, reliable, and compatible with nearly every custom conversion using a J1772 port. But as EV infrastructure evolves and more components hit the aftermarket, DC fast charging is quickly becoming part of the conversation, especially for high-end builds and long-range projects.

Companies such as Ampere EV are now offering NACS charging as part of their EV powertrain options.

If you’re designing a vehicle from the ground up or modernizing a classic with performance in mind, charging compatibility is no longer just a footnote; it’s part of the design equation.

Here’s the current landscape:

CCS retrofits are technically possible but are often complex and costly, requiring a charge management controller (CMC) to handle communication with the network.
NACS retrofits are in development, with some aftermarket support beginning to emerge.
Adapters between standards exist but can be hit-or-miss due to handshake protocols and voltage compatibility. Many require advanced control systems to work properly.

Even if your first build doesn’t include DC fast charging, understanding how it works can help you future-proof your design. As more OEMs adopt NACS and public stations begin offering dual support, staying flexible is key. What’s standard today might look very different in just a few years.

So whether you’re sticking with J1772 or exploring CCS or NACS, one thing’s for sure: the future of EV charging is fast, and it’s already on its way.