Hacker News Reader

Comment by guardiangod | Hacker News Reader

Backward compatibility with J1772 (AC only charging standard).

Can’t the Tesla plug also do that? You can plug a Tesla into a normal outlet.

You cannot plug a Tesla into a normal outlet without a brick of an adaptor.

The adapter isn’t big. I put it in my pocket sometimes. But it’s worth noting the Tesla plug that does both AC and Fast Dc charging is smaller than the J1772 plug that does AC alone. And the J1772 to Tesla adapter is purely mechanical and conductive, no active components. So it’s cheap and you can buy 3Rd party ones.

Oh! We're talking about the connector. For some reason I thought we were connecting to wall power, which requires a brick sized power converter and thick cable.

It's not even a power converter, it's just some contactors and a microcontroller that tells the EV what sort of power source it is. The EV talks to the micro and if the input power is compatible the contactors close and deliver AC directly to the EV. The charger onboard the EV takes that AC input and converts it.

It’s also functionally identical to the equivalent J1772 device. You can (unwisely!) use dumb adapters in either direction.

It’s unwise because there is no way for a passive cable or adapter to tell the car to limit current to anything below 80A.

> It’s unwise because there is no way for a passive cable or adapter to tell the car to limit current to anything below 80A.

Yes there is, the adapter just passively adapts all 5 pins. The J1772, CCS Combo 1, and NACS are all pin compatible. The EV has an ECU that can detect what is plugged by sensing the configuration on those 3 pins and negotiate accordingly. For older Teslas to support the CCS Combo 1 adapter they require an ECU upgrade. The adapter only needs to passively connect all 5 pins.

You’re missing the point.

If your dumb adapter is actually rated for 80A and the J1772 protocol is never extended to allow more than 80A, you’re fine.

If your dumb adapter is rated for less than 80A, but your car and charger negotiate more than the rating of your adapter, you may have a problem. See, for example:

https://cdn.shopify.com/s/files/1/0045/1110/5114/files/JDapt...

Are there any EVs besides that Model S/X that can L2 charge above 11.5kW?

If everyone adopts NACS then this won't be an issue because even the lower end adapters support 11.5kW. The longer it takes for North America to standardize, the greater the possibility of your hypothetical scenario becoming a reality.

*https://www.amazon.com/gp/product/B09DCTJCTV/

I use a dumb adapter. The J1772 charge box still is able to talk to the Tesla car to negotiate charge current. The digital pins are still present.

I have a Nissan Leaf and have a brick of an adaptor for J1772. I think it's required for some kind of ground fault or other check circuitry because I know the car has its own built in charging system that deals with AC.

Oh, come on. A Tesla (excuse me, "NACS") plug with AC adapter attached is still less than half the size of a CCS connector. This is what it looks like:

https://shop.tesla.com/product/sae-j1772-charging-adapter

It's just a passive connector. All the signaling is handled internal to the car (which actually supports CCS too, there's a equally passive similar-looking CCS adapter you can buy).

Reply on news.ycombinator.com