Gen3 Wall Connector Question - load sharing?

[ehahn9]

About a year ago, I installed two Gen 3 wall connectors. Due to my (old) house's electrical panel, they are both on the same circuit breaker circuit. I'm *eagerly* awaiting the long-promised load sharing feature so I can start using the second wall connector. Otherwise, it's basically garage wall art ;-)

Does anyone happen to know if Tesla has or will (ever!?) release load sharing support? Very frustrating at the moment... thanks!

ps: My wall connectors claim "no update available" and they are on v1.4.4. Is that the latest?

 

[kayak1]

Gen 2 can be on the same circuit breaker, Gen 3 are not supposed to share a circuit breaker.
Please see page 24: https://www.tesla.com/sites/default...ng/Gen3_WallConnector_Installation_Manual.pdf

 

[kishkaru]

Branch Circuit Conductors and Ground Wire

• For sites with multiple Wall Connectors, each Wall Connector must have its own branch circuit with L1,L2/N, and Ground.

The firmware-based power sharing feature enables up to 16 Wall Connectors installed at the same site to intelligently share the site's total available power via unit-to-unit Wi-Fi. This minimizes the need for many residential and commercial applications to have specific electrical upgrades for concurrent multi-vehicle charging.

During the commissioning process,
• Wall Connectors are allocated to individual branch circuits (each up to 60 amps)
• Total power is allocated to the group of linked Wall Connectors

Total current output of Wall Connectors that share power will never exceed the site's total allocated power

So the only purpose of the "load sharing" feature of the Gen 3 Wall Connector is to avoid the homeowner from having to do a main panel upgrade?
(Since each WC is required to have its own dedicated circuit back to the main or subpanel)

 

[Rocky_H]

So the only purpose of the "load sharing" feature of the Gen 3 Wall Connector is to avoid the homeowner from having to do a main panel upgrade?
(Since each WC is required to have its own dedicated circuit back to the main or subpanel)

No, people still continue to get this wrong. It's not every single one with a full dedicated homerun line all the way back. The way it's supposed to work (when Tesla gets around to implementing it) is still actual circuit sharing, but it's a connection method thing. They used to allow the choice of physical wire ties with things like Polaris connectors, or you could breaker each one. With the new Gen3, they just don't allow the wire splitting with Polaris connectors anymore.

You are still partially right about using a subpanel. That's basically necessary to mount the breakers. But you could do it like this: Run a 50A circuit from out of your main, 200 feet away to a parking lot or separate building, and then there, you can have the subpanel with breakers for 5 or 10 or more wall connectors. And if they are configured properly, they will make sure not to exceed that 50A (40A continuous) of the total capacity of that main circuit. See the savings? Your main wiring run out to the subpanel doesn't have to be extra thick wire to support 10X the current as if they were all separate runs to 10 wall connectors.

 

[kishkaru]

Yeah I get it. But at the end of the day, each Wall Connector must be connected to its own circuit breaker, and each circuit breaker needs to be installed inside a subpanel. Both of these add to the cost of installation. The subpanel then runs a single circuit back to the main panel. If you don't want to use a subpanel (e.g. your main panel is in the garage very close to the WC's), you can run X circuits back to the main panel instead, but still use the "load sharing" function of the Gen 3 WC's to avoid going over the total power capacity of your main breaker.

I think what the OP was hoping to do was skip the subpanel / individual circuits per WC and use Polaris connectors instead to split the circuit, and run the single circuit back to the main panel.

 

[JamesinNorCal]

Yeah I get it. But at the end of the day, each Wall Connector must be connected to its own circuit breaker, and each circuit breaker needs to be installed inside a subpanel. Both of these add to the cost of installation. The subpanel then runs a single circuit back to the main panel. If you don't want to use a subpanel (e.g. your main panel is in the garage very close to the WC's), you can run X circuits back to the main panel instead, but still use the "load sharing" function of the Gen 3 WC's to avoid going over the total power capacity of your main breaker.

I think what the OP was hoping to do was skip the subpanel / individual circuits per WC and use Polaris connectors instead to split the circuit, and run the single circuit back to the main panel.

You pretty much always need the subpanel unless you have an enormous electrical service. If you have one 50 amp breaker in the main panel, then the load calc you will have to do to get a permit will need to show you have 62.5 amps extra capacity for your EV charger. This is because continuous loads need to be capable of 125% of rating. It doesn't matter if you have multiple 50 amp breakers in the subpanel in your garage, it's still a single 50 amp circuit in the main panel.

Instead, if you run both 50 amp charger wires to the main panel, now you have to show you have a spare 125 amps in the main panel. Not likely in a residence. You would probably need a 300 amp service at least. And if you priced it out, the cost of two sets of #6 copper is very expensive. The cost of a 2 breaker subpanel and 2 x 50 amp breakers is about $50, many times less than the cost of the second wire, unless the main panel is on the side of the garage.

 

[miimura]

You pretty much always need the subpanel unless you have an enormous electrical service. If you have one 50 amp breaker in the main panel, then the load calc you will have to do to get a permit will need to show you have 62.5 amps extra capacity for your EV charger. This is because continuous loads need to be capable of 125% of rating. It doesn't matter if you have multiple 50 amp breakers in the subpanel in your garage, it's still a single 50 amp circuit in the main panel.

Instead, if you run both 50 amp charger wires to the main panel, now you have to show you have a spare 125 amps in the main panel. Not likely in a residence. You would probably need a 300 amp service at least. And if you priced it out, the cost of two sets of #6 copper is very expensive. The cost of a 2 breaker subpanel and 2 x 50 amp breakers is about $50, many times less than the cost of the second wire, unless the main panel is on the side of the garage.

the 125% is applied to the continuous load of 40 amps, which gives you 50A for a 50A circuit and breaker. You don't add 62.5A to anything.

 

[TechnoBabble]

This is dumb. If we need to install 2 dedicated circuits for these gen 3 wall connectors, whats to stop someone from disabling the load sharing feature and overloading the circuit? Where I live, the inspectors would want to see a load calculation based on each circuit. They are not going to care if load sharing is enabled because the end user can easily disable it.
Load sharing with the gen 2 hpwc was far better if you ask me.

 

[Rocky_H]

Load sharing with the gen 2 hpwc was far better if you ask me.

Well, this part is probably true. There were a few things that were better with the old ones. Although that could only share up to four. The Gen3 is supposedly going to enable sharing a lot more, like 16 I think.

This is dumb. If we need to install 2 dedicated circuits for these gen 3 wall connectors, whats to stop someone from disabling the load sharing feature and overloading the circuit? Where I live, the inspectors would want to see a load calculation based on each circuit. They are not going to care if load sharing is enabled because the end user can easily disable it.

Sharing of EVSEs has been written into NEC for at least a few years now, so inspectors better be inspecting to that standard and accepting shared communication as a code-compliant installation. What's to stop people? Well obviously nothing at all. People can obviously do any kind of stupid and wrong and blatantly not code compliant foolhardy thing that comes into their heads. Nothing is going to stop people from doing that. Why would this be any different than any other thing? People can violate code and not pass an inspection any time they want.

 

[TechnoBabble]

Looks like

Well, this part is probably true. There were a few things that were better with the old ones. Although that could only share up to four. The Gen3 is supposedly going to enable sharing a lot more, like 16 I think.

Sharing of EVSEs has been written into NEC for at least a few years now, so inspectors better be inspecting to that standard and accepting shared communication as a code-compliant installation. What's to stop people? Well obviously nothing at all. People can obviously do any kind of stupid and wrong and blatantly not code compliant foolhardy thing that comes into their heads. Nothing is going to stop people from doing that. Why would this be any different than any other thing? People can violate code and not pass an inspection any time they want.

Here in Ontario Canada, all gen 3s need a 60 amp breaker and #6 wire because the current can be cranked up far to easily over the network.

 

[Rocky_H]

Looks like

Here in Ontario Canada, all gen 3s need a 60 amp breaker and #6 wire because the current can be cranked up far to easily over the network.

...for the final leg of the wiring run to each--yes. That's how the installation is defined. You can do a smaller single run most of the way, to some form of junction box or subpanel, where they will then need to be split out, with a breaker for each.

But then you are talking about Canadian Electric Code, which I am not as familiar with, so I don't know if they have the same written acceptance of current sharing between EVSEs being acceptable.

 

[MattChristian]

Passing on what I just heard from my favorite electrician who installs many Tesla Wall Connectors (TWC).

He just received the firmware to enable power load sharing between two TWC Gen 3 models. File was sent to him (and other installers) from Tesla in an email attachment a few days ago, not available to public over the air yet.

He setup load sharing on a new pair of TWC Gen 3, communicates via wireless only, no control wires required. Supports up to four TWC Gen 3 at a time right now, and 2 to 4 can power load share up to a single 100 Amp circuit. Each TWC Gen 3 still only outputs 48 Amps each max so won't boost older Model S with dual-chargers. His working theory is that a set of load sharing TWC Gen 3 will replace old/existing installs of paired Tesla destination chargers.

I don't personally have a TWC Gen 3, but I have a pair of load sharing TWC Gen 2.

 

[Rocky_H]

He just received the firmware to enable power load sharing between two TWC Gen 3 models. File was sent to him (and other installers) from Tesla in an email attachment a few days ago, not available to public over the air yet.

Whoa, well that's interesting. This is the first place I have heard of this being available in any form yet. Thanks for sharing.

 

[blecchus_rex]

This is working for me as of a few minutes ago! The wall connectors did not see an update when I checked for one via the web UI... but you can manually upload the necessary firmware (version 21.18.1) via the link and instructions (specifically the "Offline Firmware Updates" section here:

Troubleshooting a Wall Connector | Tesla Support

Wall Connector is the most convenient charging solution for houses, apartments, hospitality properties and workplaces. Find out how to troubleshoot and commission a Wall Connector.

www.tesla.com

NOTE: I had to actually perform a factory reset of both wall connectors in order to convince them to take the manually provided firmware.

Subsequent to getting every v3 wall connector up to the necessary firmware revision and back online, follow the instructions here:

Wall Connector Power Sharing | Tesla Support

With Power Sharing, you can allow up to six 3 Wall Connectors to share power and charge multiple vehicles at once. Learn how to set up and troubleshoot Power Sharing.

www.tesla.com

Voila!

And to think it's only been 11 months since I had these installed!

 

[TechnoBabble]

This is really cool. So can two hpwc's be fed from one 60 amp circuit like the gen 2 with a splitter box?

 

[theatrus]

Brilliant. Adding a second car so seriously considering this.

 

[miimura]

This is really cool. So can two hpwc's be fed from one 60 amp circuit like the gen 2 with a splitter box?

No, I believe the manual says that each Gen 3 Wall Connector should have its own breaker. One way to install two WCs for power sharing where there was previously one, would be to put a small sub-panel with two 60A breakers, fed by the original 60A breaker in the main panel.

 

[blecchus_rex]

No, I believe the manual says that each Gen 3 Wall Connector should have its own breaker. One way to install two WCs for power sharing where there was previously one, would be to put a small sub-panel with two 60A breakers, fed by the original 60A breaker in the main panel.

It does suggest that - depicted on Page 24 here:

https://www.tesla.com/sites/default/files/support/charging/Gen3_WallConnector_Installation_Manual.pdf

And from some of the electrical code I dug up a while back (but to be clear I'm definitely not an Electrician):

210.17 Electric Vehicle Branch Circuit.

210.17 Electric Vehicle Branch Circuit. An outlet(s) installed for the purpose of charging electric vehicles shall be supplied by a separate branch circuit. This circuit shall have no other outlets.
Informational Note: See 625.2 for the definition of Electric Vehicle.

But it begs the question: what's the point of the power sharing feature then? There's nothing in place that detects or prevents sharing of a single circuit that might be over-subscribed were 2 (or more) wall connectors operating concurrently. And although they'd be on the same breaker it'd still afford overcurrent / short-circuit up to it's maximum, no? WRT the scenario mentioned above (a sub-panel splitting a 60AMP into two), what's the real advantage afforded?

I also understand NEC allows a managed system load to be considered the maximum permitted by that system instead of the sum of all the branch capacities (the power sharing feature in the Tesla HPWC's ostensibly providing the managed system capability). So perhaps the only real utility of the power sharing feature is to allow over-subscription at the panel / sub-panel level... and not on individual circuits?

 

[Darblish]

It does suggest that - depicted on Page 24 here:

https://www.tesla.com/sites/default/files/support/charging/Gen3_WallConnector_Installation_Manual.pdf

And from some of the electrical code I dug up a while back (but to be clear I'm definitely not an Electrician):

210.17 Electric Vehicle Branch Circuit.



But it begs the question: what's the point of the power sharing feature then? There's nothing in place that detects or prevents sharing of a single circuit that might be over-subscribed were 2 (or more) wall connectors operating concurrently. And although they'd be on the same breaker it'd still afford overcurrent / short-circuit up to it's maximum, no? WRT the scenario mentioned above (a sub-panel splitting a 60AMP into two), what's the real advantage afforded?

I also understand NEC allows a managed system load to be considered the maximum permitted by that system instead of the sum of all the branch capacities (the power sharing feature in the Tesla HPWC's ostensibly providing the managed system capability). So perhaps the only real utility of the power sharing feature is to allow over-subscription at the panel / sub-panel level... and not on individual circuits?

That’s correct. You can run a bunch of separate 60-amp circuits from your 200-amp (or whatever) service, and tell the wall connectors that you’ve got a total of 90 amps (or again, whatever the real number is in your situation) capacity for them. Then they will each have their full 60 amps per connector if there’s just one vehicle charging, but will collectively not exceed the total when multiple are plugged in.

 

[miimura]

It does suggest that - depicted on Page 24 here:

https://www.tesla.com/sites/default/files/support/charging/Gen3_WallConnector_Installation_Manual.pdf

And from some of the electrical code I dug up a while back (but to be clear I'm definitely not an Electrician):

210.17 Electric Vehicle Branch Circuit.



But it begs the question: what's the point of the power sharing feature then? There's nothing in place that detects or prevents sharing of a single circuit that might be over-subscribed were 2 (or more) wall connectors operating concurrently. And although they'd be on the same breaker it'd still afford overcurrent / short-circuit up to it's maximum, no? WRT the scenario mentioned above (a sub-panel splitting a 60AMP into two), what's the real advantage afforded?

I also understand NEC allows a managed system load to be considered the maximum permitted by that system instead of the sum of all the branch capacities (the power sharing feature in the Tesla HPWC's ostensibly providing the managed system capability). So perhaps the only real utility of the power sharing feature is to allow over-subscription at the panel / sub-panel level... and not on individual circuits?

Power sharing uses a special rule for this case because the loads manage the aggregate current draw. Sorry, I don't have the code reference handy. Technically, since there is a breaker for each Wall Connector, there is a dedicated circuit. However, without power sharing to modulate the combined draw, you would easily overload or trip the common feeder from the main panel. The benefit is that when you only plug in one car, it can charge at the full 60 amps. When you plug in two cars, it will divide the available current between the two cars. If one finishes earlier than the other, it will re-allocate more power to the car still charging. Most likely it will still reserve 6A for the car that's connected, but not charging, since that is the minimum signal in the J1772 standard.