CCS v2...

[Ed Lee]

On Sunday, June 12, 2022 at 9:30:03 AM UTC-7, ke...@kjwdesigns.com wrote:

On Friday, 10 June 2022 at 18:29:21 UTC-7, Ed Lee wrote:
...
BTW, the J1772 duty cycle peak at 60A (100%) and many DC chargers are much higher than that. So, they are not following the signal spec anyway, why bother with forcing the same physical size spec.
You lost me. J1772 is not a DC charger. It\'s a 240V AC charger, which you say is 60A although I\'ve never seen one above 30A.
J1772 duty cycle is fraction of 60A. Namely, 25% is 15A, 50% is 30A, etc. They never figure that J1772 would exceed 60A.
Why are you talking about fast DC and J1772 pins? I know I\'m going to regret asking.
The signalling pins of J1772 and CCS are the same. They are physically the same in CCS vehicles.

When they designed CCS, they tried to keep it compatible with existing J1772 spec. But most DC chargers are way over 60A, or more than 100% duty cycle. So, it starts with a 1kHz with any duty cycle and then both side (charger and chargee) pretty much ignore it and look at the battery voltage instead.

Hence, a big part of the signalling spec is meaningless, when you can just look at the battery voltage. Keeping big plug/socket with meaningless pins is just meaningless.
DC charging does not use the PWM information for charge control at all. Neither does it use the battery voltage. The charging station does not know what the battery voltage is supposed to be or the vehicle\'s limits of charging current at any instant.

No for CCS, but Yes for CDM. CDM DCFC knows exactly what the vehicle voltage is via CAN.

There is a separate method using a modulated high-frequency signal CP line that allows bidirectional packetized communication between the vehicle and the charging station. This can do everything from billing to allowing V2G functionality.

kw

Moduled on the DC lines? If so, more reason to ditch the J1772 part of CCS..

 

[ke...@kjwdesigns.com]

On Sunday, 12 June 2022 at 10:52:18 UTC-7, Ed Lee wrote:

On Sunday, June 12, 2022 at 9:30:03 AM UTC-7, ke...@kjwdesigns.com wrote:
On Friday, 10 June 2022 at 18:29:21 UTC-7, Ed Lee wrote:
...
BTW, the J1772 duty cycle peak at 60A (100%) and many DC chargers are much higher than that. So, they are not following the signal spec anyway, why bother with forcing the same physical size spec.
You lost me. J1772 is not a DC charger. It\'s a 240V AC charger, which you say is 60A although I\'ve never seen one above 30A.
J1772 duty cycle is fraction of 60A. Namely, 25% is 15A, 50% is 30A, etc. They never figure that J1772 would exceed 60A.
Why are you talking about fast DC and J1772 pins? I know I\'m going to regret asking.
The signalling pins of J1772 and CCS are the same. They are physically the same in CCS vehicles.

When they designed CCS, they tried to keep it compatible with existing J1772 spec. But most DC chargers are way over 60A, or more than 100% duty cycle. So, it starts with a 1kHz with any duty cycle and then both side (charger and chargee) pretty much ignore it and look at the battery voltage instead.

Hence, a big part of the signalling spec is meaningless, when you can just look at the battery voltage. Keeping big plug/socket with meaningless pins is just meaningless.
DC charging does not use the PWM information for charge control at all. Neither does it use the battery voltage. The charging station does not know what the battery voltage is supposed to be or the vehicle\'s limits of charging current at any instant.
No for CCS, but Yes for CDM. CDM DCFC knows exactly what the vehicle voltage is via CAN.

What has Chademo go to do with it? - you were taking about J1772 and CCS.

You could use CAN as a communication link but when the CCS spec was created they didn\'t define it that way. They used an approach that exploited the J1772 safety mechanism and didn\'t add any more connections other than the DC power pins.

It is not completely obvious why they didn\'t just use the AC power pins for DC power as Tesla does. The CCS DC pins are slightly larger diameter but not much. Tesla gets up to 300A using their pins that are similar diameter to the J1772 power pins.

There is a separate method using a modulated high-frequency signal CP line that allows bidirectional packetized communication between the vehicle and the charging station. This can do everything from billing to allowing V2G functionality.

kw
Moduled on the DC lines? If so, more reason to ditch the J1772 part of CCS.

No the communication link does not go over the DC lines - the modulated RF signal rides on the Control Pilot line together with the PWM signal used for safety and AC signaling.

I wonder why they didn\'t use a simple digital protocol similar to RS232. It doesn\'t really need CAN. It is always going to be point-to-point, no need to multiple end points and it would never be directly attached to a car\'s main network for security reasons.

kw

 

[Ed Lee]

On Monday, June 13, 2022 at 10:47:14 AM UTC-7, ke...@kjwdesigns.com wrote:

On Sunday, 12 June 2022 at 10:52:18 UTC-7, Ed Lee wrote:
On Sunday, June 12, 2022 at 9:30:03 AM UTC-7, ke...@kjwdesigns.com wrote:
On Friday, 10 June 2022 at 18:29:21 UTC-7, Ed Lee wrote:
...
BTW, the J1772 duty cycle peak at 60A (100%) and many DC chargers are much higher than that. So, they are not following the signal spec anyway, why bother with forcing the same physical size spec.
You lost me. J1772 is not a DC charger. It\'s a 240V AC charger, which you say is 60A although I\'ve never seen one above 30A.
J1772 duty cycle is fraction of 60A. Namely, 25% is 15A, 50% is 30A, etc. They never figure that J1772 would exceed 60A.
Why are you talking about fast DC and J1772 pins? I know I\'m going to regret asking.
The signalling pins of J1772 and CCS are the same. They are physically the same in CCS vehicles.

When they designed CCS, they tried to keep it compatible with existing J1772 spec. But most DC chargers are way over 60A, or more than 100% duty cycle. So, it starts with a 1kHz with any duty cycle and then both side (charger and chargee) pretty much ignore it and look at the battery voltage instead.

Hence, a big part of the signalling spec is meaningless, when you can just look at the battery voltage. Keeping big plug/socket with meaningless pins is just meaningless.
DC charging does not use the PWM information for charge control at all. Neither does it use the battery voltage. The charging station does not know what the battery voltage is supposed to be or the vehicle\'s limits of charging current at any instant.
No for CCS, but Yes for CDM. CDM DCFC knows exactly what the vehicle voltage is via CAN.

What has Chademo go to do with it? - you were taking about J1772 and CCS.

You could use CAN as a communication link but when the CCS spec was created they didn\'t define it that way. They used an approach that exploited the J1772 safety mechanism and didn\'t add any more connections other than the DC power pins.

It is not completely obvious why they didn\'t just use the AC power pins for DC power as Tesla does. The CCS DC pins are slightly larger diameter but not much. Tesla gets up to 300A using their pins that are similar diameter to the J1772 power pins.
There is a separate method using a modulated high-frequency signal CP line that allows bidirectional packetized communication between the vehicle and the charging station. This can do everything from billing to allowing V2G functionality.

kw
Moduled on the DC lines? If so, more reason to ditch the J1772 part of CCS.
No the communication link does not go over the DC lines - the modulated RF signal rides on the Control Pilot line together with the PWM signal used for safety and AC signaling.

RF over fixed wire is making thing more complicated than necessary. No wonder CCS chargers break often.

> I wonder why they didn\'t use a simple digital protocol similar to RS232. It doesn\'t really need CAN. It is always going to be point-to-point, no need to multiple end points and it would never be directly attached to a car\'s main network for security reasons.

The charger needs to disable vehicle\'s drive train and route the electrical junction. It\'s not just talking to the battery alone. Of course, it should work in cooperation with the main vehicle controller.

 

[ke...@kjwdesigns.com]

On Tuesday, 14 June 2022 at 06:46:50 UTC-7, Ed Lee wrote:

On Monday, June 13, 2022 at 10:47:14 AM UTC-7, ke...@kjwdesigns.com wrote:
....

kw
Moduled on the DC lines? If so, more reason to ditch the J1772 part of CCS.
No the communication link does not go over the DC lines - the modulated RF signal rides on the Control Pilot line together with the PWM signal used for safety and AC signaling.
RF over fixed wire is making thing more complicated than necessary. No wonder CCS chargers break often.

Unlikely that is the cause of any failure. In my experience it is usually higher level network issues.

I wonder why they didn\'t use a simple digital protocol similar to RS232.. It doesn\'t really need CAN. It is always going to be point-to-point, no need to multiple end points and it would never be directly attached to a car\'s main network for security reasons.
The charger needs to disable vehicle\'s drive train and route the electrical junction. It\'s not just talking to the battery alone. Of course, it should work in cooperation with the main vehicle controller.

I said it can\'t connect \"directly\". Of course it has to interact with other parts of the vehicle but it cannot be allowed to directly connect to the car\'s CAN network or malicious actors could compromise the security of the vehicle.

If it has to go through a bridge anyway for security reasons then the physical media is immaterial.

The charger end does not have any particular reason to use CAN so something more straightforward would have been appropriate.

Using a standard PLC protocol (the technique modulated RF over the CP line) I thought was unusual but it is a standard and allows the line to be used for both functions.

kw

 

[Ricky]

On Monday, June 13, 2022 at 1:47:14 PM UTC-4, ke...@kjwdesigns.com wrote:

On Sunday, 12 June 2022 at 10:52:18 UTC-7, Ed Lee wrote:
On Sunday, June 12, 2022 at 9:30:03 AM UTC-7, ke...@kjwdesigns.com wrote:
On Friday, 10 June 2022 at 18:29:21 UTC-7, Ed Lee wrote:
...
BTW, the J1772 duty cycle peak at 60A (100%) and many DC chargers are much higher than that. So, they are not following the signal spec anyway, why bother with forcing the same physical size spec.
You lost me. J1772 is not a DC charger. It\'s a 240V AC charger, which you say is 60A although I\'ve never seen one above 30A.
J1772 duty cycle is fraction of 60A. Namely, 25% is 15A, 50% is 30A, etc. They never figure that J1772 would exceed 60A.
Why are you talking about fast DC and J1772 pins? I know I\'m going to regret asking.
The signalling pins of J1772 and CCS are the same. They are physically the same in CCS vehicles.

When they designed CCS, they tried to keep it compatible with existing J1772 spec. But most DC chargers are way over 60A, or more than 100% duty cycle. So, it starts with a 1kHz with any duty cycle and then both side (charger and chargee) pretty much ignore it and look at the battery voltage instead.

Hence, a big part of the signalling spec is meaningless, when you can just look at the battery voltage. Keeping big plug/socket with meaningless pins is just meaningless.
DC charging does not use the PWM information for charge control at all. Neither does it use the battery voltage. The charging station does not know what the battery voltage is supposed to be or the vehicle\'s limits of charging current at any instant.
No for CCS, but Yes for CDM. CDM DCFC knows exactly what the vehicle voltage is via CAN.

What has Chademo go to do with it? - you were taking about J1772 and CCS.

You could use CAN as a communication link but when the CCS spec was created they didn\'t define it that way. They used an approach that exploited the J1772 safety mechanism and didn\'t add any more connections other than the DC power pins.

It is not completely obvious why they didn\'t just use the AC power pins for DC power as Tesla does. The CCS DC pins are slightly larger diameter but not much. Tesla gets up to 300A using their pins that are similar diameter to the J1772 power pins.

The J1772 pins simply are not rated for the high currents on the DC pins. Tesla designed their connector for high current DC from the start. J1772 didn\'t.

There is a separate method using a modulated high-frequency signal CP line that allows bidirectional packetized communication between the vehicle and the charging station. This can do everything from billing to allowing V2G functionality.

kw
Moduled on the DC lines? If so, more reason to ditch the J1772 part of CCS.
No the communication link does not go over the DC lines - the modulated RF signal rides on the Control Pilot line together with the PWM signal used for safety and AC signaling.

Ed is good at mixing up the details. He likes odd arrangements, oblivious that there are huge amounts of inertia in any standard. No charger company is going to want to change connectors now. Likewise, what car company wants to obsolete their previously sold cars... well, maybe that\'s not valid.


> I wonder why they didn\'t use a simple digital protocol similar to RS232. It doesn\'t really need CAN. It is always going to be point-to-point, no need to multiple end points and it would never be directly attached to a car\'s main network for security reasons.

I don\'t know much about the CCS protocol. I do know the J1772 standard is very, very simple and doesn\'t necessitate digital electronics in the EVSE, even if they all have an MCU.

--

Rick C.

--- Get 1,000 miles of free Supercharging
--- Tesla referral code - https://ts.la/richard11209

 

[ke...@kjwdesigns.com]

On Tuesday, 14 June 2022 at 09:26:18 UTC-7, Ricky wrote:

On Monday, June 13, 2022 at 1:47:14 PM UTC-4, ke...@kjwdesigns.com wrote:
On Sunday, 12 June 2022 at 10:52:18 UTC-7, Ed Lee wrote:
On Sunday, June 12, 2022 at 9:30:03 AM UTC-7, ke...@kjwdesigns.com wrote:
On Friday, 10 June 2022 at 18:29:21 UTC-7, Ed Lee wrote:
...
BTW, the J1772 duty cycle peak at 60A (100%) and many DC chargers are much higher than that. So, they are not following the signal spec anyway, why bother with forcing the same physical size spec.
You lost me. J1772 is not a DC charger. It\'s a 240V AC charger, which you say is 60A although I\'ve never seen one above 30A.
J1772 duty cycle is fraction of 60A. Namely, 25% is 15A, 50% is 30A, etc. They never figure that J1772 would exceed 60A.
Why are you talking about fast DC and J1772 pins? I know I\'m going to regret asking.
The signalling pins of J1772 and CCS are the same. They are physically the same in CCS vehicles.

When they designed CCS, they tried to keep it compatible with existing J1772 spec. But most DC chargers are way over 60A, or more than 100% duty cycle. So, it starts with a 1kHz with any duty cycle and then both side (charger and chargee) pretty much ignore it and look at the battery voltage instead.

Hence, a big part of the signalling spec is meaningless, when you can just look at the battery voltage. Keeping big plug/socket with meaningless pins is just meaningless.
DC charging does not use the PWM information for charge control at all. Neither does it use the battery voltage. The charging station does not know what the battery voltage is supposed to be or the vehicle\'s limits of charging current at any instant.
No for CCS, but Yes for CDM. CDM DCFC knows exactly what the vehicle voltage is via CAN.

What has Chademo go to do with it? - you were taking about J1772 and CCS.

You could use CAN as a communication link but when the CCS spec was created they didn\'t define it that way. They used an approach that exploited the J1772 safety mechanism and didn\'t add any more connections other than the DC power pins.

It is not completely obvious why they didn\'t just use the AC power pins for DC power as Tesla does. The CCS DC pins are slightly larger diameter but not much. Tesla gets up to 300A using their pins that are similar diameter to the J1772 power pins.
The J1772 pins simply are not rated for the high currents on the DC pins. Tesla designed their connector for high current DC from the start. J1772 didn\'t.

I agree - although I was surprised that the connector could not be improved to increase the current capability.

With the bidirectional communication link available in CCS there would be no ambiguity over the current capability of the connector.

CCS2 connectors do support up to 500A with cooling (200A without) and have individual temperature sensors for each contact so the charging rate can be throttled if necessary.

There is a separate method using a modulated high-frequency signal CP line that allows bidirectional packetized communication between the vehicle and the charging station. This can do everything from billing to allowing V2G functionality.

kw
Moduled on the DC lines? If so, more reason to ditch the J1772 part of CCS.
No the communication link does not go over the DC lines - the modulated RF signal rides on the Control Pilot line together with the PWM signal used for safety and AC signaling.
Ed is good at mixing up the details. He likes odd arrangements, oblivious that there are huge amounts of inertia in any standard. No charger company is going to want to change connectors now. Likewise, what car company wants to obsolete their previously sold cars... well, maybe that\'s not valid.
I wonder why they didn\'t use a simple digital protocol similar to RS232.. It doesn\'t really need CAN. It is always going to be point-to-point, no need to multiple end points and it would never be directly attached to a car\'s main network for security reasons.
I don\'t know much about the CCS protocol. I do know the J1772 standard is very, very simple and doesn\'t necessitate digital electronics in the EVSE, even if they all have an MCU.

The the simple J1772 analog control technique used with CCS does have that virtue that the safety related aspect of enabling/disabling power does not require that any software be in the path.

kw
....