Apparently using a NACS to J1772 adapter /could/ damage your vehicle.

[Dark-Fx]

Saw this on Facebook, supposedly it was a false alert for them but the fact that this error even exists pretty much confirms to me that Rivian will have to change a lot more hardware than just the charge port for the NACS conversion.

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[YouKnowWhatsUp]

This looks like someone used an ac adapter on a dc charger. That would
Never be ok on any ev.

 

[Friar_J]

Presumably they used a NACS to j1772 adaptor to try to use a Tesla supercharger. The j1772 port does not have any high voltage DC pins so basically they tried to pass high voltage DC through AC only connectors. They're lucky they didn't spark anything or start a fire.

 

[edman007]

I'm somewhat surprised that NACS powers up without seeing battery voltage, I would expect for the supercharger to verify the battery contactors are active before applying power. Maybe it varies by charger? I really wish the spec was free and open.

But this is why switching to NACS is not trivial, you can't have a passive adapter that does both, the onboard charger MUST be redesign to be HV tolerant.

 

[Dark-Fx]

I'm somewhat surprised that NACS powers up without seeing battery voltage, I would expect for the supercharger to verify the battery contactors are active before applying power. Maybe it varies by charger? I really wish the spec was free and open.

But this is why switching to NACS is not trivial, you can't have a passive adapter that does both, the onboard charger MUST be redesign to be HV tolerant.

Tesla had an early issue with their CCS on certain stations that would ignore the maximum vehicle voltage during isolation testing, and blow up the onboard charger. Those chargers were 800V capable stations. This is probably the same effective issue going on.

 

[edman007]

Tesla had an early issue with their CCS on certain stations that would ignore the maximum vehicle voltage during isolation testing, and blow up the onboard charger. Those chargers were 800V capable stations. This is probably the same effective issue going on.

That's what I'm missing, isolation testing. I guess the charger must do an isolation test prior to starting DCFC, an isolation test on the AC pins will surely roast the AC charger.

I'm probably going to have to find the spec and read it.

 

[momo3605]

Anyone know what ended up happening to this guy?

 

[CharonPDX]

Yeah, this seems suspicious. CCS and J1772 both do low-voltage “handshake and negotiation” over the small J1772 pins before they allow any high-power to flow over the bigger (AC J1772 or DC CCS) pins.
Using a J1772 adapter on a Supercharger absolutely won’t send DC power. The only problem I can think of is if the “negotiation” signal is different enough that the DC Supercharger signal is over a wrong pair of wires compared to J1772, *and* it’s an old not-CCS-complaint Superchatger that has no protections against sending the wrong signal.

 

[simpsonhomer]

Anyone know what ended up happening to this guy?

 

[edman007]

Yeah, this seems suspicious. CCS and J1772 both do low-voltage “handshake and negotiation” over the small J1772 pins before they allow any high-power to flow over the bigger (AC J1772 or DC CCS) pins.
Using a J1772 adapter on a Supercharger absolutely won’t send DC power. The only problem I can think of is if the “negotiation” signal is different enough that the DC Supercharger signal is over a wrong pair of wires compared to J1772, *and* it’s an old not-CCS-complaint Superchatger that has no protections against sending the wrong signal.

So what was mentioned earlier, which is probably right, is isolation testing. If you use a J1772 adapter then you connect the DC charger pins to the AC pins on the car. Once connected the car and charger agree on DC charging. The DC charger then checks the wiring by applying 500V and verifying the car takes no power, nothing shorts to ground, and reports that it saw it. Unfortunately this is connected to the AC charger which cannot pass this test, it arcs through the AC charger and destroys the charger. The DC charger then reports an isolation fault

Basically one of the steps in the handshake is check for sparks...and it sparks

 

[CharonPDX]

So what was mentioned earlier, which is probably right, is isolation testing. If you use a J1772 adapter then you connect the DC charger pins to the AC pins on the car. Once connected the car and charger agree on DC charging. The DC charger then checks the wiring by applying 500V and verifying the car takes no power, nothing shorts to ground, and reports that it saw it. Unfortunately this is connected to the AC charger which cannot pass this test, it arcs through the AC charger and destroys the charger. The DC charger then reports an isolation fault

Basically one of the steps in the handshake is check for sparks...and it sparks

Except the “negotiate” protocols for J1772 (and AC Tesla, which uses J1772’s signaling protocol, which is why simple adapters work in both directions) and DC protocols (Superchatger and CCS) while they use the same data pins, are completely different. The base handshake would fail before SC even *thinks* about sending 400+V DC.

 

[edman007]

Except the “negotiate” protocols for J1772 (and AC Tesla, which uses J1772’s signaling protocol, which is why simple adapters work in both directions) and DC protocols (Superchatger and CCS) while they use the same data pins, are completely different. The base handshake would fail before SC even *thinks* about sending 400+V DC.

No, the adapter is just a couple wires, it has no smarts at all (they'll run the data pins through some safety switches and safety thermocouples, but that's it). Because of this, when it's a DC charger on the other end the car sees a DC charger and they start their handshake. It doesn't fail until they test the power pins.

Think of it like international AC plug adapters, they are just a bunch of wires changing the pins. Your cell phone charger works on them because it can detect the kind of power and use it, but a US coffee maker will blow up on UK power. The adapters are just wires connecting the pins, and they only work because you only connect them to things the label says they will work with. Some configurations they don't work and can result in fire.

 

[dduffey]

Except the “negotiate” protocols for J1772 (and AC Tesla, which uses J1772’s signaling protocol, which is why simple adapters work in both directions) and DC protocols (Superchatger and CCS) while they use the same data pins, are completely different. The base handshake would fail before SC even *thinks* about sending 400+V DC.

You are correct, but on the Tesla plug the DC and AC pins are ALSO the same (shared) pins, not separated like CCS. i.e. CCS has four powered pins, 2 AC 2 DC. Tesla "plug" only has 2 powered pins which is both the AC and DC depending on the source.

So, when using an AC adapter and connecting to an AC source the AC EVSE says "Hey there, I am an AC source" ... The Rivian says "great, I can take your AC" and then power is sent to the Rivian AC pins.

But if you use that same AC adapter, now the supercharger says (on the same data pins) "Hey, I am a DC source" and then Rivian says "Great, I can take DC" ... And then the adapter gets the DC power source and transmits it to the AC pins on the Rivian side, instead of the CCS DC pins.

There is nothing in the AC wired adapter to tell the NACS source it (the adapter) is only AC capable and that only AC should be provided on the powered pins.

 

[Riviaenz]

This looks like someone used an ac adapter on a dc charger. That would
Never be ok on any ev.

Wasn’t there a similar problem with leaded and Diesel pumps? While those nozzles were designed not to fit in an unleaded gas car, you could be unleaded in leaded and diesel cars/trucks.

How do you prevent that? It seems like it could be part of the handshake but a CCS car wouldn’t know that there is nothing plugged into the DC contacts until a suddenly massive DC jolt hits it’s AC power contacts. Seems just like filling a Pb Diesel vehicle with unleaded problem. A sticker solved that right?

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