Tesla's NACS and the Future of Fast Charging in North America

[P.S.Mangelsdorf]

As you all may have seen, both Ford and GM have announced that they will move from CCS to Tesla's charging standard (now called NACS) beginning in 2025. If others follow suit, I think we will need to figure out a solution for conversions to use NACS. I think it is reasonable to expect that, if other manufacturers switch to NACS, charging networks will begin to phase out multi-plug stations in favor of just offering NACS as they add new stations and replace old ones.

Tesla has allegedly opened their standard, but the documentation is fairly thin. The good news is that it appears to use the CCS protocols, but different hardware. The standard states on page 11:

• "For DC charging, communication between the EV and EVSE
  shall be power line communication over the control pilot line
  as depicted in DIN 70121."

• "The North American Charging Standard is compatible with
  “plug and charge” as defined in ISO-15118"

This would seem to indicate that the current projects to develop an open source CCS could be utilized for part of the NACS standard.

The glaring issue that I see is that it sounds like, from the press releases and articles, that Ford and GM have worked out some sort of app connection with Tesla to initiate and control charges. Its unclear to me how exactly we'd deal with that functionality. I have no idea if it is feasible to implement plug-and-charge, and if the Tesla stations would even allow charging a vehicle that wasn't in their database of production vehicles.

Unfortunately, this is beyond my technical depth. I can find information and I'm more than willing to use my vehicles as a test bed, but I'm not even sure where to begin on the hardware/code issues. Attached are the technical specs downloaded from Tesla, and linked below are Ford and GM's press releases.

https://media.ford.com/content/fordmedi ... ers--.html
https://news.gm.com/newsroom.detail.htm ... 08-gm.html

[celeron55]

It seems to me NACS is basically CCS2 with a different physical connector, so that's not an issue.

However you bring a good point about payments. I hope Tesla activates payment via app for all EVs in the US like it has done in Europe. While Europe is better positioned for this as Tesla uses CCS2 here, I think the Magic Dock is good indication Tesla wants to do this also in the US.

[windydrew]

This is already done.... Its on the app and you just add a credit card to the app to start charging.

It seems to me NACS is basically CCS2 with a different physical connector, so that's not an issue.

However you bring a good point about payments. I hope Tesla activates payment via app for all EVs in the US like it has done in Europe. While Europe is better positioned for this as Tesla uses CCS2 here, I think the Magic Dock is good indication Tesla wants to do this also in the US.

[windydrew]

Also like this section:
4.6.1 The North American Charging Standard is compatible with
Vehicle to X (i.e. Vehicle to load, Vehicle to home, vehicle
to grid) power transfer. Future versions of this technical
specification will specify the functional requirements and
specifications required to achieve vehicle to X power transfer.

[peternooy]

From what I have captured during model Y charging session, Tesla does not support ISO 15118, so no suppory for plug and charge at the moment.

[P.S.Mangelsdorf]

This is already done.... Its on the app and you just add a credit card to the app to start charging.

Yes, but will/does that work at stations without magicdock?

[Shockazulu1]

I'm in Iowa, a very anti EV state.
Funny now with the new EV government incentives.....
In the last few months, already 10 new DC fast chargers have been installed, within 10 miles of my house.
Each one has both ChadeMo/CCS1.
Last year there was only one every 55 miles down the interstate.
I don't know what the motivation is, but I like it.
I have 40 amp home charger and probably wouldn't use the chargers in my area.
But I hope this is a sign for other areas around the country, so I can travel with an EV more easily.

[Skudak]

From what I have captured during model Y charging session, Tesla does not support ISO 15118, so no suppory for plug and charge at the moment.

Did you capture the communication between the charger and the car? Any chance you have that somewhere I could look at? I was about to build an adapter to go between a supercharger and my Model S so I could capture the communication.

[peternooy]

Will share the pcap file when I get back to the lab, in around two weeks. It is an incomplete session, time out after 12 sec at pre-charge. The session is to find out if Tesla close DC contactor during simulated charging, but it does not.

Regarding your plan to build an adaptor, is it passive sniffing or proxy adaptor?

[Skudak]

Will share the pcap file when I get back to the lab, in around two weeks. It is an incomplete session, time out after 12 sec at pre-charge. The session is to find out if Tesla close DC contactor during simulated charging, but it does not.

Regarding your plan to build an adaptor, is it passive sniffing or proxy adaptor?

It would be a "man in the middle" that would read incoming data from either direction and repeat it out the other side. The concern with just passive sniffing is you don't know which way the data is coming from.

Tesla's documentation on NACS isn't thorough enough, and I'm too cheap to pay the hundreds of dollars for a copy of the DIN70121 standard (Or IEC 61851-1) unless I know for certain there's documentation on the sequence of communication

[uhi22]

The sequence in human-readable form is here: https://github.com/uhi22/pyPLC#example-flow
If it comes to the details, there is a wireshark plugin to decode everything. Any idea how to create this man in middle is welcome.

[peternooy]

It would be a "man in the middle" that would read incoming data from either direction and repeat it out the other side. The concern with just passive sniffing is you don't know which way the data is coming from.

Tesla's documentation on NACS isn't thorough enough, and I'm too cheap to pay the hundreds of dollars for a copy of the DIN70121 standard (Or IEC 61851-1) unless I know for certain there's documentation on the sequence of communication

IMHO, you shoud get the spec, if help.

Anyway, here is the Tesla pcap file.

Tesla-Y14.pcap00.zip

(6.31 KiB) Downloaded 62 times

[mikeselectricstuff]

I'm too cheap to pay the hundreds of dollars for a copy of the DIN70121 standard (Or IEC 61851-1) unless I know for certain there's documentation on the sequence of communication

IEC & ISO standards can be had very cheaply from Estonia
https://www.evs.ee/en
e.g. IEC61851-1 for 36 Euros, or browse it for 24 hours for E2.40

[P.S.Mangelsdorf]

So we finally have some more information on the use of Tesla Superchargers by non-Teslas in the US.
https://electrek.co/2024/02/29/ford-tes ... available/

As I read it, the concern I originally had about starting the charge appears to be somewhat correct. From this, Ford owners will start the charge session either via plug and charge, or via the Ford app, which I presume means there is some communication on the back end between Ford and Tesla's systems. It does mention that the Tesla app is not necessary, which to me is bad news, because that seems to signal that Tesla's stations will only be open to vehicles built by manufacturers that have agreements with them, and charge initialization will be via those automakers' systems.

It's good to know the adapter is fairly simple and will be openly available this summer, but if this is how all of these arrangements are, it sounds to me like it's going to be hard/impossible to use Tesla's charging stations with a conversion.

[uhi22]

I understand it the other way around. The Ford owner does not need the Tesla app, and is happy with Plug&Charge. All others can use the Tesla App, as now in Europe. I just had a look to my europe-Tesla-app, and find a lot of open SuC in the US. Hope this also works on an US mobile.

[P.S.Mangelsdorf]

I understand it the other way around. The Ford owner does not need the Tesla app, and is happy with Plug&Charge. All others can use the Tesla App, as now in Europe. I just had a look to my europe-Tesla-app, and find a lot of open SuC in the US. Hope this also works on an US mobile.

That would be interesting. My understanding was that up to this point, the only SCs in the US that non-Teslas could access via the Tesla app were those with the "Magic Dock" CCS adapter built in, which are spreading but far from common.

Here's an interesting test: Do you see any Superchargers available in North Carolina? Plugshare shows none with MagicDock.

[uhi22]

Zero in NC, and just one in SC: Columbia, SC - Forest Drive

[P.S.Mangelsdorf]

Zero in NC, and just one in SC: Columbia, SC - Forest Drive

Yeah, that's one of the Magic Dock locations. They're spreading faster than I thought but still not a lot of coverage.

[nubster]

What about folks with a NACS/Tesla charger at home (I.e., wall or mobile connectors)? I assume these units lack all of the payment gateway/authorization stuff...

Does charging via NACS connector at home already work with one of Damien's PCS boards (or Zombie VCU) or another OI-based solution? Is there another thread or wiki somewhere that discusses this use case?

[asavage]

The Tesla (High Power) Wall Connector (that's what Tesla calls their home L2 chargers, as well as "Destination Charger" when installed at eg a hotel) is L2, AC, and does not phone home, just like most all other private charging stations.

L2 (AC) charging is a very different animal from DCFC. The beauty of NACS is that it re-purposes the physical power pins in the connector to convey either DC or AC, depending on what's communicated by the EVSE, and switches the power routing in the vehicle on demand: incoming AC gets sent to the OBC; incoming DC gets sent directly to the HV battery.

That allows the elimination of two big pins in the connector, and is the reason it's svelte as compared to CCSx, which uses separate pins for AC and DC charge sessions.

[But, as NACS has provision for only two AC lines, it can't do 3-phase AC charging, which makes it pretty much entirely unsuitable for use in, eg, the EU, where 3-ph power is ubiquitous and it's nearly impossible to get 40A 1-ph power at home; most seem to be 16A 3-ph, from what I hear.]

I can't answer your Q about the capabilities of those products.

[P.S.Mangelsdorf]

What about folks with a NACS/Tesla charger at home (I.e., wall or mobile connectors)? I assume these units lack all of the payment gateway/authorization stuff...

I think that is correct, they're basically AC charging with a different pinout, I think? I know I saw discussion elsewhere on switching between AC and DC for regular CCS, I assume this would be similar.

I would also assume that DC NACS on a non-Tesla station should work using plain CCS comms with the NACS port. I plan to test this at some point, but I'm working on other issues at the moment.

Does charging via NACS connector at home already work with one of Damien's PCS boards (or Zombie VCU) or another OI-based solution? Is there another thread or wiki somewhere that discusses this use case?

I'm not sure on that; its worth some exploration, but shouldn't be too hard.