SAE is standardizing NACS this year – making it less dependent on Tesla

[Dark-Fx]

Am I interpreting this properly - the proposed new standard (NACS) is not what Tesla is presently using on their vehicles and charging stations? Rather, it's a new plug who's design is not complete, or at least is not fully tested, and is supposed to be backwards compatible with the present Tesla receptacle?

1000V "NACS" connectors don't exist anywhere in public. Not on plugs nor receptacles. Tesla says they've done testing on them. I'd hope that testing was demonstrated to the other automotive companies before they signed onto this program, but that hasn't been stated in any press release for the switch.

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[Craigins]

For the sake of implementation simplicity it will end up being two simple low cost passive adapters:

An AC adapter for L1/l2 where J1772 AC pins are connected to the Tesla pins (These are already available and already provided in some cases).

A DCFC adapter for L3 where CCS DC pins are connected to the Tesla pins. This is essentially what the magic dock is (sans the physical locks).

Isolation relays, if needed, will be implemented in the chargers (already there) and vehicle (most likely already there for many vehicles) with interlock communication over the control pins.

If I were designing an adapter to hand put to my customers who already purchased a ccs vehicle, I would want the circuit that detects the ac vs dc, which are not in the current ccs vehicles.

You cannot trust a customer to use the proper adapter in each situation when the plugs are identical.

These won't be dumb pass through adapters.

 

[Dark-Fx]

If I were designing an adapter to hand put to my customers who already purchased a ccs vehicle, I would want the circuit that detects the ac vs dc, which are not in the current ccs vehicles.

You cannot trust a customer to use the proper adapter in each situation when the plugs are identical.

These won't be dumb pass through adapters.

I have been wondering what will happen if I plug my CCS vehicle into a supercharger after this change with one of the AC adapters.

 

[CharonPDX]

Am I interpreting this properly - the proposed new standard (NACS) is not what Tesla is presently using on their vehicles and charging stations? Rather, it's a new plug who's design is not complete, or at least is not fully tested, and is supposed to be backwards compatible with the present Tesla receptacle?

If this is really where we are, there could be a very long lag for the NACS in-service date.

Yes. The NACS connector is "backward compatible" with the currently-in-use Tesla connector, but is not identical.

NACS is also specified to use CCS electrical protocol, where current Superchargers use the same protocol as CHAdeMO. (That's why Tesla was able to offer a CHAdeMO adapter early on - because they were the same protocol. Only later did they make their cars "bilingual" able to "speak both CHAdeMO and CCS" and offer the CCS adapter.)

When Tesla "released NACS" the official specification was purely for the physical/mechanical components, with a couple placeholder sections basically saying "use CCS for the electrical bits" and "it should be able to run at the voltages and amperages in use by CCS." (Yes, I read the whole document when it came out - I have friends who helped work on CCS and MCS, and I'm a nerd.)

 

[CharonPDX]

I have been wondering what will happen if I plug my CCS vehicle into a supercharger after this change with one of the AC adapters.

Nothing. The Supercharger will attempt to send the "hey, car, speak CCS to me!" signal. The AC adapter doesn't connect the DC pins, so the car will reply with "I'm speaking J1772, whaddaya want?" The Supercharger will refuse to send power. (Yes, CCS and J1772 use different communication protocols, in spite of CCS using the J1772 data pins for communication. Because J1772's "communication protocol" is ridiculously simple, while CCS needs more complex communication.)

 

[Dark-Fx]

Nothing. The Supercharger will attempt to send the "hey, car, speak CCS to me!" signal. The AC adapter doesn't connect the DC pins, so the car will reply with "I'm speaking J1772, whaddaya want?" The Supercharger will refuse to send power. (Yes, CCS and J1772 use different communication protocols, in spite of CCS using the J1772 data pins for communication. Because J1772's "communication protocol" is ridiculously simple, while CCS needs more complex communication.)

Communications still happen on the J1772 side of the port for CCS. There are isolation tests and such that depend on the DC side being connected, but if it starts those, it's going to blow up your OBC. This is why CCS1 is better engineered than NACS, because there is no chance of this happening with CCS1 alone.

The "DC side" of the "NACS" connector is the exact same as the AC side of a J1772 port. Destination adapters connect them together and they are dumb. The PLC signals likely will still pass through on them but I definitely haven't tested it.

 

[Longreach]

If I were designing an adapter to hand put to my customers who already purchased a ccs vehicle, I would want the circuit that detects the ac vs dc, which are not in the current ccs vehicles.

You cannot trust a customer to use the proper adapter in each situation when the plugs are identical.

These won't be dumb pass through adapters.

It is impractical to implement high current switching in an adapter, so there will be two simple adapters: AC and DCFC. You will get the DCFC free from your manufacturer, as they have promised, and some manufacturers already give you the AC adapter.

There may be some minimal ID detection in the primarily passive adapter, but not needed if the ends detect the relevant connections.

Overall this whole adapter thing will be relatively easy to use for owners equipped with legacy CCS connectors. Note you can still use native J1772 home charging for as long as you want, so most people will only use the free DCFC adapter on long trips.

 

[Zoidz]

Just because it's called the north american standard doesn't make it that. SAE is still going to maintain the CCS1 standard.

Yes, and at the risk of a poor analogy, VHS and BetaMax are still both standards even though VHS won the war.

If I were designing an adapter to hand put to my customers who already purchased a ccs vehicle, I would want the circuit that detects the ac vs dc, which are not in the current ccs vehicles.

You cannot trust a customer to use the proper adapter in each situation when the plugs are identical.

These won't be dumb pass through adapters.

Unfortunately, there will likely be some charlatan companies that popup online selling "inexpensive universal adapters" that don't work, or even worse, cause damage to the car.

 

[Craigins]

It is impractical to implement high current switching in an adapter, so there will be two simple adapters: AC and DCFC. You will get the DCFC free from your manufacturer, as they have promised, and some manufacturers already give you the AC adapter.

There may be some minimal ID detection in the primarily passive adapter, but not needed if the ends detect the relevant connections.

Overall this whole adapter thing will be relatively easy to use for owners equipped with legacy CCS connectors. Note you can still use native J1772 home charging for as long as you want, so most people will only use the free DCFC adapter on long trips.

As dark stated, what happens when someone uses the dcfc adapter at a level 2 AC charger?

 

[SANZC02]

There may be some minimal ID detection in the primarily passive adapter, but not needed if the ends detect the relevant connections.

This is where the issue will be, the NACS to CCS1 will need to communicate with the SC to enable the charge. It cannot rely on the connector itself as the SC and Tesla L2 has the same connector. Certainly solvable but there is a reason it is at least a year out, there will need to be a decent amount of effort put in to make it idiot proof.

 

[Longreach]

This is where the issue will be, the NACS to CCS1 will need to communicate with the SC to enable the charge. It cannot rely on the connector itself as the SC and Tesla L2 has the same connector. Certainly solvable but there is a reason it is at least a year out, there will need to be a decent amount of effort put in to make it idiot proof.

Agreed it must idiot proof (and cheap to implement, which means no smarts, other than ID or type detection).

But I think it is very close as is, with very minor refinements to validate the interlocking conditions.

 

[Dark-Fx]

As dark stated, what happens when someone uses the dcfc adapter at a level 2 AC charger?

it "should" still be safe in either direction but I would not bet anything on there never being some sort of a malfunction.

 

[MP3Mike]

If I were designing an adapter to hand put to my customers who already purchased a ccs vehicle, I would want the circuit that detects the ac vs dc, which are not in the current ccs vehicles.

You cannot trust a customer to use the proper adapter in each situation when the plugs are identical.

These won't be dumb pass through adapters.

I think that they absolutely will be dumb adapters.

I have been wondering what will happen if I plug my CCS vehicle into a supercharger after this change with one of the AC adapters.

Nothing. Communication would happen, they would start the test and see that the HV pins on the vehicle weren't connected to the charger and abort with an error.

Communications still happen on the J1772 side of the port for CCS. There are isolation tests and such that depend on the DC side being connected, but if it starts those, it's going to blow up your OBC. This is why CCS1 is better engineered than NACS, because there is no chance of this happening with CCS1 alone.

I'm pretty sure that the CCS standard has plenty of safeguards in place to prevent HV DC from going to unintended places. I can't recall if CCS requires the vehicle to provide HV DC on the connector before the charger is allowed to start or not. But even before that an isolation test is performed which I think would fail with the charger HV DC pins connected to the OBC. (Or to nothing if the vehicle has contactors between the charge port and OBC.)

As dark stated, what happens when someone uses the dcfc adapter at a level 2 AC charger?

Nothing. Communication would happen, they would start the test and see that the AC pins on the vehicle weren't connected to the charger and abort with an error. Even if the charging somehow started the AC would be sent to the DC pins that aren't connected to anything because the vehicle hasn't closed the DC fast charge contactors.

 

[MP3Mike]

Has everybody seen that Polestar and EA have announced support for NACS today as well?

https://media.polestar.com/global/e...o-enable-access-to-tesla-supercharger-network

https://media.electrifyamerica.com/en-us/releases/223

 

[Dark-Fx]

I'm pretty sure that the CCS standard has plenty of safeguards in place to prevent HV DC from going to unintended places. I can't recall if CCS requires the vehicle to provide HV DC on the connector before the charger is allowed to start or not. But even before that an isolation test is performed which I think would fail with the charger HV DC pins connected to the OBC. (Or to nothing if the vehicle has contactors between the charge port and OBC.)

Tesla had issues with certain CCS chargers blowing up their OBCs because the chargers were providing the maximum voltage they could produce during the initial testing instead of what the Tesla vehicles were rated to. They had to make engineering changes to increase their withstand voltage. Shit definitely wouldn't have happened if they didn't share the pins between AC and DC.

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