Tesla Wall Connector load sharing protocol

[MP3Mike]

Which dip switch disables the Tesla protocol it in a Gen2 HPWC?

I guess it depends if you have a newer or older HPWC. (Apparently they removed the ability to disable it in the newer ones.) You can check under the front cover to see what it says:

Or you could just try flipping dip switch 2 down, and see if it works.

 

[whitex]

I guess it depends if you have a newer or older HPWC. (Apparently they removed the ability to disable it in the newer ones.) You can check under the front cover to see what it says:

View attachment 877876

Or you could just try flipping dip switch 2 down, and see if it works.

I have one of the first Gen2 and a later, Elon signature engraved Gen2. Neither show the above setting for the dip switch in their manuals. The question is, how can I check whether or not the HPWC is trying to talk the Tesla protocol or not? Which signal does it use and what protocol?

 

[MP3Mike]

I have one of the first Gen2 and a later, Elon signature engraved Gen2. Neither show the above setting for the dip switch in their manuals. The question is, how can I check whether or not the HPWC is trying to talk the Tesla protocol or not? Which signal does it use and what protocol?

Did you check under the front face plate to see if the switch is identified?

The two protocols are Tesla, Single Wire CAN, or J-1772, Pilot based. I would think the easiest way is to plug in a J-1772 EV and see how quickly it starts charging.

 

[whitex]

Did you check under the front face plate to see if the switch is identified?

The two protocols are Tesla, Single Wire CAN, or J-1772, Pilot based. I would think the easiest way is to plug in a J-1772 EV and see how quickly it starts charging.

J1772 EV is still not here, preparing for its arrival in February (unless things shift again, originally it was supposed be here mid December this year). Do you know if the Tesla protocol is initiated by the HPWC or by the vehicle (i.e. should I be seeing it on the Pilot as long as I clip it to 9V indicating a connected J1772 vehicle), or is it just waiting for the car to start sending CAN commands?

 

[MP3Mike]

Sorry, I don't know how the negotiation works.

 

[hcsharp]

J1772 EV is still not here, preparing for its arrival in February (unless things shift again, originally it was supposed be here mid December this year). Do you know if the Tesla protocol is initiated by the HPWC or by the vehicle (i.e. should I be seeing it on the Pilot as long as I clip it to 9V indicating a connected J1772 vehicle), or is it just waiting for the car to start sending CAN commands?

It's initiated by the WC. It it doesn't get any response it times out and stops trying. At that point it assumes it's connected to a non-Tesla vehicle. If you remove the bypass circuit in the adapter then the load sharing should work fine. The load sharing protocol assumes that a car that's plugged in but not charging is consuming 6A.

 

[whitex]

It's initiated by the WC. It it doesn't get any response it times out and stops trying. At that point it assumes it's connected to a non-Tesla vehicle. If you remove the bypass circuit in the adapter then the load sharing should work fine. The load sharing protocol assumes that a car that's plugged in but not charging is consuming 6A.

Is there a reply (CAN or other protocol) which I can send back to WC to tell it to stop talking and enable charging immediately? I could put a microcontroller inline instead of the passive bypass circuit.

 

[miimura]

Is there a reply (CAN or other protocol) which I can send back to WC to tell it to stop talking and enable charging immediately? I could put a microcontroller inline instead of the passive bypass circuit.

That seems like a counter-productive approach to me. Any activity that it recognizes will probably prolong the fallback to legacy J1772 protocol.

There is no reason to implement a CAN "cancel" command. If a connected vehicle can speak CAN, why not say something useful instead of "shut up".

 

[brkaus]

@whitex what is your end goal?

 

[hcsharp]

Is there a reply (CAN or other protocol) which I can send back to WC to tell it to stop talking and enable charging immediately? I could put a microcontroller inline instead of the passive bypass circuit.

^^^ @miimura is correct. The system already enables charging almost immediately when there is no response to the CAN comms over the pilot wire. I've seen several of these Gen 2 load sharing setups that work fine with one node connected to a J1772 vehicle. Maybe we're misunderstanding what you really want to do with this system? What is your ultimate goal?

Edit: I see @brkaus beat me to the punch line.

 

[whitex]

@whitex what is your end goal?

2 HPWC's load sharing 80A, each capable of delivering 80A, but one with J1772 connector and one with Tesla connector.

I can swap the Tesla connector with J1772 no problem, but then HPWC can take 10-15 seconds to time out the CAN, during which the EV on J1772 throws a charging error. Pulling pilot down to 9V (fooling HPWC into thinking there is an EV connected) solves the timeout problem but now messes with load balancing as one HPWC always thinks it has an EV connected to it so it always allocates some of the 80A to it.

 

[whitex]

^^^ @miimura is correct. The system already enables charging almost immediately when there is no response to the CAN comms over the pilot wire.

Define "almost immediately"?

 

[brkaus]

I have this adaptor on my WC most of the time. Tesla to J1772 Adapter – EVSE Adapters

My leaf starts charging immediately if the adaptor was on the cable. But I do have to wait 5-10 sec after I put the adaptor on the cable for it to work.

I've read threads by others here that a J1772 adaptor on a WC will still properly load share if there are two WC setup.

 

[whitex]

I've read threads by others here that a J1772 adaptor on a WC will still properly load share if there are two WC setup.

I will be trying it soon enough.

 

[brkaus]

I will be trying it soon enough.

let us know!

 

[hcsharp]

2 HPWC's load sharing 80A, each capable of delivering 80A, but one with J1772 connector and one with Tesla connector.

I can swap the Tesla connector with J1772 no problem, but then HPWC can take 10-15 seconds to time out the CAN, during which the EV on J1772 throws a charging error. Pulling pilot down to 9V (fooling HPWC into thinking there is an EV connected) solves the timeout problem but now messes with load balancing as one HPWC always thinks it has an EV connected to it so it always allocates some of the 80A to it.

Thanks for clarifying. Does the EV that throws a charging error automatically reset and start charging after a few seconds? Many cars will do that, and they should if they are strictly J1772 compatible. If I remember correctly the master charger will allocate 6A to a car that is plugged in but not charging. The car that might need 80A would still get 74A in this scenario. Would that meet your needs? In a situation where you really needed 80A then you would have to unplug the other car from the adapter.

A note of caution: The last time I checked, none of the Tesla 2 to J1772 adapters being sold had thermal shut-down protection. Most of them are only rated for 40A. I've seen fires (first hand) when charging a J1772 vehicle at 30A when the contacts were dirty. I've also seen a lot of melted connectors that didn't start a fire but were close to it. Periodically check all your EV charging cables, connectors, adapters and other equipment so you know when something needs its contacts cleaned or other servicing. I can't overstate this. There was a time when I would have dismissed this advice while thinking "I'm careful, that won't happen to me." I'm wiser now that I've seen some bad things happen even when the EV owner was doing everything right. If your J1772 adapter doesn't overheat the first time don't assume it will always be that way.

 

[whitex]

Thanks for clarifying. Does the EV that throws a charging error automatically reset and start charging after a few seconds? Many cars will do that, and they should if they are strictly J1772 compatible.

It's a Porsche Taycan, but not here yet (ETA moved from December to February), so cannot tell you for sure. Perhaps you know anyone with a Taycan which has tried this?

If I remember correctly the master charger will allocate 6A to a car that is plugged in but not charging. The car that might need 80A would still get 74A in this scenario. Would that meet your needs? In a situation where you really needed 80A then you would have to unplug the other car from the adapter.

I was trying to avoid the 6A reserve (hence my question about the ability to reduce the timeout), but worst case scenario I will live with it, assuming that is only 6A. Not planning to use an actual adapter (see below).

A note of caution: The last time I checked, none of the Tesla 2 to J1772 adapters being sold had thermal shut-down protection. Most of them are only rated for 40A. I've seen fires (first hand) when charging a J1772 vehicle at 30A when the contacts were dirty. I've also seen a lot of melted connectors that didn't start a fire but were close to it. Periodically check all your EV charging cables, connectors, adapters and other equipment so you know when something needs its contacts cleaned or other servicing. I can't overstate this. There was a time when I would have dismissed this advice while thinking "I'm careful, that won't happen to me." I'm wiser now that I've seen some bad things happen even when the EV owner was doing everything right. If your J1772 adapter doesn't overheat the first time don't assume it will always be that way.

Thanks for the caution, is is definitely worth mentioning to anyone reading this. I did buy a Tesla Tap 80A adapter, since the Taycan I ordered will come with 80A onboard charger (Tesla Tap has 40A, 60A and 80A IIRC). That said, on the home HPWC setup I don't plan to use the adapter, but instead just replacing the Tesla cable with 80A J1772 cable. Furthermore, that cable does have a spare line to which I will connect a thermistor which I will place in the J1772 handle, which will actually give the HPWC a handle temperature, same as the Tesla handle (I think I have a matching thermistor, need to run a few checks to make 100% sure as Tesla might have used different in different wall chargers). I also check my installations with FLIR camera to make sure nothing in the path is overheating when under full load. I did my own 100A HPWC installation, has been working for many years now, the government inspector's comment on it was "overengineered" as I prefer to upsize my wires, install solid overspec parts, etc.

 

[hcsharp]

Furthermore, that cable does have a spare line to which I will connect a thermistor which I will place in the J1772 handle, which will actually give the HPWC a handle temperature, same as the Tesla handle (I think I have a matching thermistor, need to run a few checks to make 100% sure as Tesla might have used different in different wall chargers).

Sounds like you're knowledgeable and have a good handle on it (no pun intended!) I'm afraid I don't know anybody who has tried a Taycan with the load sharing system.

Please do report back to let us know the specs on the thermistor, and how the Taycan works out.

 

[tga]

That said, on the home HPWC setup I don't plan to use the adapter, but instead just replacing the Tesla cable with 80A J1772 cable. Furthermore, that cable does have a spare line to which I will connect a thermistor which I will place in the J1772 handle, which will actually give the HPWC a handle temperature, same as the Tesla handle (I think I have a matching thermistor, need to run a few checks to make 100% sure as Tesla might have used different in different wall chargers).

Can you share part number/sources for the cable and thermistor?

 

[whitex]

Can you share part number/sources for the cable and thermistor?

The J1772 cable I picked up from ebay a while back, the listing no longer exists. It's hard to find the 80A J1772 handles/pins nowadays - probably because they are not as popular (not many EV's have 80A capability). The thermistor which I think will work is https://www.digikey.com/en/products/detail/epcos-tdk-electronics/B57164K0103J000/739847
it's 10K@25C but I have not verified the Beta parameter. Apparently they are different in different chargers, so need to take a few measurements of the original Tesla cable+handle at couple of temperatures to be sure. This one looks to have a similar form factor to one in one of the Mobile chargers, a picture of which I found on the internet: