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by chrisseaton 1311 days ago
Why is CCS so absolutely enormous and so technically limited? What's the story behind how it got so bad? There must be some kind of trade-off Tesla took that CCS didn't?
4 comments

https://news.ycombinator.com/item?id=27907051

TLDR CCS wanted to be backwards compatible, while Tesla planned fast charging to be first class with their standard. At the time, no one was doing fast charging at Supercharger currents (150kw). CCS was bolted on to J1772.

Considering how early that decision was made in the timeline of electric vehicles (how early we still even are) — getting saddled with a backwards compatibility kludge kind of sucks.
It’s still early days and certainly not too late to change it.
That's true for the US, but the EU mandates that all vehicle charging stations support CCS Combo 2.[1] They'd have to undo their mandate to allow better chargers, and I don't think that'll happen any time soon.

1. https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CEL...

CCS 2 is a different discussion, because at least it supports something the Tesla connector doesn't, 3 phase charging.
That really doesn’t explain all of it, J1772 is not really that big. CCS adds a ton of bulk on top of J1772.
J1772 can't carry enough amps through those pins. So it needs two more huge pins in a separate compartment.

CCS isn't the absolute smallest way to add two more huge pins, but it's pretty close.

Why keep the J1772 connector? Only the data pins are used. I'm sure there's a way to make a connector that's just the CCS part and fudge the data pins into it.

Then supporting the old cars just happens with a dongle.

Don't ask me that, I'm just answering why the decision to keep it caused such a huge connector.
Is bigger actually worse in this case?

At least in theory, it should be possible to make it mechanically stronger than a smaller connector.

I've heard of charge station cable connectors failing do repeated bending stress, and my car has multiple warning stickers saying not to plug into a charging cable that is under tension.

> technically limited

Is it? I can go to a 350kW charger with CCS1. What's the max for a supercharger? 250kW?

Says 1 MW?
2500 amps? I don't think liquid cooling is enough to allow for that.

You are probably thinking of the megawatt charger for the semi, which is different.

A regular V3 supercharger caps out at 250kW. There are rumors that the V4 might get closer to 400kW, but as far as I know those remain rumors. There's also a rumor of an upgrade of V3 superchargers to about 325kW, which would at least be getting close to CCS1.

Only going on what the article says "the Tesla charging connector is the most proven in North America, offering AC charging and up to 1 MW DC charging in one slim package".
But my source is also Tesla themselves - and yours is 2019 and mine 2022?
I'm not privy to CCS design process, however several possibilities spring to mind:

- Backward compatibility: CCS is backward-compatible extension of J plug, and can't share AC and DC lines due to that.

- Higher safety margins in CCS

- CCS design by committee

- Better engineers at Tesla