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Discussion Starter #1
With respect to BEVs we are currently in the inevitable standards war. And. because there's huge investment in the rival systems it's not one that will be easily resolved.

Tesla have an adaptor which enables them to use ChaDeMo. But it's fairly clear that an adaptor one could reasonably carry in the car is unlikely to be able to mediate between a DC and AC system.

But how about adapting between the two mainstream DC charge systems, ChaDeMo and CCS? Are the voltages compatible? Handshake shouldn't be too hard, basically it just involves a small CPU in the adaptor.
 

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Adapt in which direction ? CCS charger to Chademo car or vica versa ? As one does earth tests and the other doesn't, at the very least I think this would only be possible in one direction.

I suspect this is a very difficult problem with not a lot of upside in trying to implement it.
 

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Technically it is almost certainly possible but in practice the cost and size would make it completely impracticable.

When I bought my i3 I was told that CCS was the European standard but after over 3 years it seems that CHAdeMO is still the dominant system especially on the motorways despite Dale Vince stating that they would be ensuring that CCS was available in every MSA, still waiting for that to happen Dale.
 

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Handshake shouldn't be too hard, basically it just involves a small CPU in the adaptor.
The things that are particularly challenging are:
  • Mechanical locking. For DC, you must have positive locking to prevent the connector being unplugged mid-charge. CHAdeMO has this in the plug, CCS has it in the car. Hence Tesla's adapter is easy in this respect - they already have a lock in the car, and the CHAdeMO plug provides a lock on the other side of the adapter, so the adapter doesn't need to do any locking. A CHAdeMO(car) to CCS(charger) adapter would need to provide two mechanical locks interlocked to the control protocol.
  • Voltage sequencing. Things need to be organized so that when contactors close to connect the charger to the battery the voltage on both sides is the same to avoid a sudden surge of current (potentially welding the contactor and at least wearing it out) when it closes. CHAdeMO and CCS do this in a different order - IIRC, CHAdeMO makes the battery voltage appear on the connector first and the charger observes that before matching its output; CCS expects the charger to output a matching voltage before closing the vehicle contactor. Tesla's adapter has to provide a circuit to generate 400V within the adapter to get the charger to start up.
  • Power for the adapter's internal electronics. CHAdeMO provides 12V power from the charger to the car with a useful amount of current - so an adapter can use that to power its internal electronics (and any solenoid locks etc.). An adapter in the other direction (CCS charger) has almost no power available on the connector until the protocol has advanced to the point that the battery voltage is available. Such an adapter would probably have to have its own internal battery (and then what do you do if it goes flat?).
So it's not impossible, but not easy. An adapter in the CCS(car) to CHAdeMO(charger) direction is significantly easier than one in the other direction - and Tesla's adapter is in most respects equivalent to that easier case.
 

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Discussion Starter #6
The things that are particularly challenging are:
  • Mechanical locking. For DC, you must have positive locking to prevent the connector being unplugged mid-charge. CHAdeMO has this in the plug, CCS has it in the car. Hence Tesla's adapter is easy in this respect - they already have a lock in the car, and the CHAdeMO plug provides a lock on the other side of the adapter, so the adapter doesn't need to do any locking. A CHAdeMO(car) to CCS(charger) adapter would need to provide two mechanical locks interlocked to the control protocol.
  • Voltage sequencing. Things need to be organized so that when contactors close to connect the charger to the battery the voltage on both sides is the same to avoid a sudden surge of current (potentially welding the contactor and at least wearing it out) when it closes. CHAdeMO and CCS do this in a different order - IIRC, CHAdeMO makes the battery voltage appear on the connector first and the charger observes that before matching its output; CCS expects the charger to output a matching voltage before closing the vehicle connector. Tesla's adapter has to provide a circuit to generate 400V within the adapter to get the charger to start up.
  • Power for the adapter's internal electronics. CHAdeMO provides 12V power from the charger to the car with a useful amount of current - so an adapter can use that to power its internal electronics (and any solenoid locks etc.). An adapter in the other direction (CCS charger) has almost no power available on the connector until the protocol has advanced to the point that the battery voltage is available. Such an adapter would probably have to have its own internal battery (and then what do you do if it goes flat?).
So it's not impossible, but not easy. An adapter in the CCS(car) to CHAdeMO(charger) direction is significantly easier than one in the other direction - and Tesla's adapter is in most respects equivalent to that easier case.
Well, I'd assume that such an adaptor would be a box with a socket for the charger end in it, and a plug for the car end on a flying cable, both obtained from wherever the charger and car manufactures get them from. A ChaDeMo to CSS would probably have to have a button to engage the latches.

A re-chargeable internal battery, topped up during each charge, would be unlikely to run out.
 

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Clearly it can be done, after all both type of charger could be powered by a large battery, and both types can change a battery.

So given the above, the science has been proven, and it just needs a little engineering to reduce the cost.......
 

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It is interesting that the LEVC TX electric taxi has both CHAdeMO and CCS. That must have been quite a challenge and add a lot of cost.
 

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It is interesting that the LEVC TX electric taxi has both CHAdeMO and CCS. That must have been quite a challenge and add a lot of cost.
Challenge, not really. Cost, perhaps.

Easier to design dual CCS and Chademo into the car than to try to make an adaptor that converts between them!
 

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Easier to design dual CCS and Chademo into the car than to try to make an adaptor that converts between them!
Yeah I get that, but ensuring safety when you have two DC connectors is key. Hopefully if one of the contractors fail closed it won't allow the other one to close.

Be interesting to see if anyone else ever does this - probably not I suspect!
 

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Yeah I get that, but ensuring safety when you have two DC connectors is key. Hopefully if one of the contractors fail closed it won't allow the other one to close.
Normally if the contactor is detected failed closed then the control logic won't allow the plug to unlock. This is just as much a hazard with a single connector.
 

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The things that are particularly challenging are:
  • Mechanical locking. For DC, you must have positive locking to prevent the connector being unplugged mid-charge. CHAdeMO has this in the plug, CCS has it in the car. Hence Tesla's adapter is easy in this respect - they already have a lock in the car, and the CHAdeMO plug provides a lock on the other side of the adapter, so the adapter doesn't need to do any locking. A CHAdeMO(car) to CCS(charger) adapter would need to provide two mechanical locks interlocked to the control protocol.
  • Voltage sequencing. Things need to be organized so that when contactors close to connect the charger to the battery the voltage on both sides is the same to avoid a sudden surge of current (potentially welding the contactor and at least wearing it out) when it closes. CHAdeMO and CCS do this in a different order - IIRC, CHAdeMO makes the battery voltage appear on the connector first and the charger observes that before matching its output; CCS expects the charger to output a matching voltage before closing the vehicle connector. Tesla's adapter has to provide a circuit to generate 400V within the adapter to get the charger to start up.
  • Power for the adapter's internal electronics. CHAdeMO provides 12V power from the charger to the car with a useful amount of current - so an adapter can use that to power its internal electronics (and any solenoid locks etc.). An adapter in the other direction (CCS charger) has almost no power available on the connector until the protocol has advanced to the point that the battery voltage is available. Such an adapter would probably have to have its own internal battery (and then what do you do if it goes flat?).
So it's not impossible, but not easy. An adapter in the CCS(car) to CHAdeMO(charger) direction is significantly easier than one in the other direction - and Tesla's adapter is in most respects equivalent to that easier case.
Arg;
Bi-directional energy flow is now possible with the CHAdeMO and (post 2012) Leafs - supported by both the protocol and the Leaf (if I am correct?). How about the CCS protocols and if so, are any of the EVs supporting the allowance protocol? Specifically the Bolt as this is the EV that is readily available to me. I'll not buy another EV unless it will (eventually) support V2G.
 

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I only know about a couple of DC chargers whose architecture is Chademo and the ccs plug is effectively an adaptor. Are there many DC chargers that only have one or the other? I’ve never seen one.
 

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Seriously, though, wouldn't 'real drivers' want to pay just a little more to have both socket types on their cars at this difficult juncture of two standards proliferating? So that comes down to the interest and imagination of car manufacturers to offer that .... and I guess they aren't actually that interested in the car driver, they just want to be seen to be collecting their 'green' shield stamps for pumping out unimaginative and poorly specified EVs.
 

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Can you explain a bit more about these earth tests? I assume it's testing continuity from the charger's earth to.. what exactly? The car chassis? How does that work if the car's on insulating rubber tyres?
I’m not sure if the earth test thing is true between ccs and chademo, however an ELI (earth loop impedance) test does not require a reference earth to test against. Effectively you test the current flow between phase and earth which when connected is a loop back to the local substation. This current needs to be high enough (impedance of the loop low enough) to make the breaker/ fuse disconnect within a certain time dependant on equipment type. The current also can’t be too high but that’s a different story.
 

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Discussion Starter #17
The "Residual Current" circuit breaker measures the difference in current between live and neutral, and cuts out if any current is mysteriously disappearing.

The equivalent with a DC circuit like this would probably just involve putting the same, fairly high voltage on both terminals and failing if there was any current flow.
 

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Well, I'd assume that such an adaptor would be a box with a socket for the charger end in it, and a plug for the car end on a flying cable, both obtained from wherever the charger and car manufactures get them from. A ChaDeMo to CSS would probably have to have a button to engage the latches.

A re-chargeable internal battery, topped up during each charge, would be unlikely to run out.

CHAdeMO charger to CCS combo(car) would probably look a lot like this, but with a CCS combo plug.

The real question is would the car socket be able to withstand the load of the adapter + CHAdeMO gun?




chademo-adaptor.jpg
 

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Discussion Starter #19
The "Residual Current" circuit breaker measures the difference in current between live and neutral, and cuts out if any current is mysteriously disappearing.

The equivalent with a DC circuit like this would probably just involve putting the same, fairly high voltage on both terminals and failing if there was any current flow.
 

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The "Residual Current" circuit breaker measures the difference in current between live and neutral, and cuts out if any current is mysteriously disappearing.

The equivalent with a DC circuit like this would probably just involve putting the same, fairly high voltage on both terminals and failing if there was any current flow.
There's nothing stopping you doing an earthed system on DC with either low EFLI and fuses or higher EFLI and RCDs, which then works exactly the same as the AC case. However, that's not what's specified for either CHAdeMO or CCS, which both specify the car traction system to be isolated from earth/chassis with isolation monitoring.

The advantage of isolation monitoring is that it allows for 'first fault' (ie. one of the wires becoming shorted to the chassis) to be detected before anything bad has happened, whereas in an earthed system it 'goes bang' on first fault (even if the earthing design makes it a safe 'bang'). This allows a car to shut down in a controlled fashion on 'first fault', rather than blowing a fuse and stopping dead.

Both CCS and CHAdeMO standards appear to require the isolation monitoring to be performed on the charger side, with the car's isolation monitoring to be disabled while connected to the charger to avoid the two fighting against each other.
 
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