Why do V4 SC and Chargepoint NACS plugs have these odd gaps?

[gsmith123]

This is a V2 Supercharger plug (V3 is similar):

Here's a V4 Supercharger plug...

...and Chargepoint's NACS plug...

Both have gaps around the outer edge (between the DC pins at the top and on each side between the DC and low voltage pins). Why is that?

Tesla's specs show this gap (page 14, among other places) for the 1000V variant and not for the 500V variant. No explanation why.

Doesn't make much sense to me. The car inlet side can't have any material in that space, or it wouldn't be compatible with existing V3 chargers. It seems like removing that material would reduce durability and would reduce isolation between the positive and negative HV pins (for higher voltage applications). Am I missing something obvious?

The only theory I have is the vehicle could use that space for a (very small) liquid cooling pipe or heatsink, if it were movable and could be pushed inwards when using an old plug.

 

[osunick]

In theory it would also allow for cars that were V4 compatible only because you could mechanically block the V3 plugs from connecting in a way that the V4 can connect to. I imagine tesla semi can only charge on v4, for instance. Mechanically keying the receiver to make sure incompatible cars can't connect to lower voltage V3.

 

[gsmith123]

That’s true although I don’t really see the point of that. Connecting a vehicle that requires, say, 800V to a charger that can only deliver 500V isn’t dangerous. It just won’t work.

 

[Tam]

That’s true although I don’t really see the point of that. Connecting a vehicle that requires, say, 800V to a charger that can only deliver 500V isn’t dangerous. It just won’t work.

800V compatible cars like Taycan, Gm Hummer, Kia/Hyundai/Hyundai... have been working with 400V Magic Dock Superchargers but just slower.

For GM, instead of 350kW, it's slowed down to 250kW.

For Taycan, instead of 350kW, it's 150.

For Hyundai/Kia/Genesis, Lucid... instead of 350kW, they slow down to 50kW...

 

[osunick]

I don't know of any car that won't support lower voltage DCFC, but I could imagine something like Semi just being incompatible with V3. It might not have anything to do with voltage, but if I were to design a plug that is backward compatible but provides a cheap mechanical way to restrict future vehicles from connecting to V3, it would look like this. I doubt it has anything to do with cooling.

 

[Tam]

...I could imagine something like Semi just being incompatible with V3...

Yes, the Tesla Semi has been compatible and charging with the existing Supercharger with an adapter since 2017. It just takes longer to charge than at a Megacharger station.

 

[MP3Mike]

Doesn't make much sense to me. The car inlet side can't have any material in that space, or it wouldn't be compatible with existing V3 chargers. It seems like removing that material would reduce durability and would reduce isolation between the positive and negative HV pins (for higher voltage applications).

I would think it would increase isolation, as electricity flowing on the surface of the plug would have to travel a further distance to make connection between the DC pins because of the missing material. (Isn't air is a better insulator than contaminants on the surface of the plug.)

My guess is that the connector can be inserted further into a 1000v inlet than a 500v inlet because of the keying.

But I'm not sure why it is necessary, I don't think there is any visible difference between a 500v and 1000v CCS1 connector. (But I think the DC pins are further apart on CCS from the begining.)

 

[gsmith123]

800V compatible cars like Taycan, Gm Hummer, Kia/Hyundai/Hyundai... have been working with 400V Magic Dock Superchargers but just slower.

I know - I was talking about a hypothetical vehicle that couldn't charge at all on 400V (I don't think any exist yet).

 

[MLXXXp]

Just a couple of shots in the dark:

1. It might make it easier to get a good insertion if the socket has some ice, dirt or or other foreign material at the bottom.
2. A less deep recess around the pins might make it easier inject plastic and release the plug from the mould, without much of a downside.

 

[NRVM3]

I would think it would increase isolation, as electricity flowing on the surface of the plug would have to travel a further distance to make connection between the DC pins because of the missing material. (Isn't air is a better insulator than contaminants on the surface of the plug.)

I believe you are correct. Isolation is maintained by the clearance (the shortest distance through the air) and creepage (the shortest distance along the surface). There are standards that specify these minimums. The 1000V connector has more creepage than the 500V. These minimums are affected by humidity, materials, pollution degree and more.

 

[phxazcraig]

Related to cooling?

 

[gsmith123]

Related to cooling?

That doesn't explain why Tesla only shows it on the 1000V variant.

(Heat generated from resistance depends only on current, not voltage. V3 SCs already push 600-700A and can get pretty hot, so if there were an easy way to improve cooling they'd want it for the 400V architecture too)

 

[terranx]

If you look at the drawings of the car end of the connector, the 1000v port has the contacts stopping about 4mm further in. I imagine they’re going for better isolation at the car end. The 500v plug won’t sit as far in on the 1000v cars, it presumably will still make sufficient contact for 500v charging.

 

[gsmith123]

the 1000v port has the contacts stopping about 4mm further in

That makes a ton of sense.

I'm having trouble actually seeing that in the drawings, though? I might just be misinterpreting the drawings.

Below are the specs for the plugs and it seems the distance from the very front of the plug to deepest part of the HV connector is the same for both (32.49mm). Shouldn't that be 4mm longer on the 1000V plug?

On the screenshot you shared above I see the depth is 33.25mm on the 1000V inlet but the 500V inlet doesn't even specify that dimension