Have power sharing between v3 Tesla Universal Wall Connector (NACS+J1772) and NACS wall connector, AMA

[EchoDelta]

Have power-sharing of a 60A line across two Tesla Wall Connectors that can balance the load (up to a total of 48 A)

The implementation of the Universal dock is surprisingly elegant and simple.

Before I used a Lectron adapter (NACS to J1772) and put it on and off the end as needed.

Tesla installation instructions require a sub-panel or load center to be added with 60 A breakers one for each Wall Connector. One of the connectors is inside and the other one connects outside via a GFCI breaker.


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[240vPlug]

Nice i have two as well. Each has its own breaker in our main panel. 60 amps site allocation. One is standard gen 3 TWC and the other is the J1772 TWC.

Its a great system the only complaint I have is that Tesla is not able to participate in most utility rebate programs for overnight charging.

Here we get a 2 cent per kwh discount for charging between 11p and 7a week nights. They use smartcar for Tesla vehicles and im hoping they add support for Rivian as Rivian is already supported by smart car. That system talks directly to the car to get charging info.

 

[EchoDelta]

Interesting. Hopefully the recent updates to the charger experience in the app (which shows the name of the Tesla car when charging) hints that they are starting to get and publish that telemetry real time.
But if it is a fixed schedule why not program it in? (Asking to learn)

 

[sub]

How do the 2 versions compare? Does the addition of the built in adapter have any downsides? If the Tesla driver is using the combo charger are they going to notice that something is different or more difficult?

 

[EchoDelta]

For the Universal charger:

A Tesla/nacs driver has zero difference in experience. Just grab the handle from the base and go.

A J1772 driver needs to push the thumb on a button at the top of the handle as they take the “nozzle” out. It doesn’t require force to either press the button or remove the combined Nacs+Adapter stub.

The versions are otherwise identical. Same base plate where conduit and connections go, and assembly mounts on top. The Universal version seemed a bit more “chunky” (bigger) in depth but otherwise same in height and width. Same curved glassy finish and vertical light show.

Also, provisioning and setup is the same, where you set station config via its own broadcast wifi but can see some stuff by visiting its IP address on the shared WiFi.

The stations don’t need internet connection to negotiate power, just be on the same WiFi. Of course if the WiFi has internet they can also broadcast status and update firmware etc

 

[dixosw]

Nice setup, thanks for the info. How is the load-balancing when both vehicles are plugged in and sharing the 48amps? Is it intelligent like it would be for plugging in 2 Teslas - where the HPWC's and the Teslas negotiate the amperage that each vehicle needs, based on state of charge etc? Supposedly, a low SOC Tesla will get higher amperage than another that is just topping off. Or does it just split the 48 amps down the middle and give each vehicle 24 amps?

 

[EchoDelta]

Nice setup, thanks for the info. How is the load-balancing when both vehicles are plugged in and sharing the 48amps? Is it intelligent like it would be for plugging in 2 Teslas - where the HPWC's and the Teslas negotiate the amperage that each vehicle needs, based on state of charge etc? Supposedly, a low SOC Tesla will get higher amperage than another that is just topping off. Or does it just split the 48 amps down the middle and give each vehicle 24 amps?

I have the same Q- I’ll try to discover the power sharing heuristics, just had 2 vehicles at 70…80% to test and it did 50% 50% which seemed reasonable.

I do wish the Tesla app showed 2 chargers in the garage instead of one for a quicker readout.

 

[GrokTime]

I am looking into getting a similar setup. Can you please clarify how the wiring works? I thought power sharing meant that each unit did not have to be on its own circuit? If I only have capacity for one 60 amp circuit wouldn't it be a violation of code to have two 60 amp breakers? Thanks.

 

[Zorg]

I am looking into getting a similar setup. Can you please clarify how the wiring works? I thought power sharing meant that each unit did not have to be on its own circuit? If I only have capacity for one 60 amp circuit wouldn't it be a violation of code to have two 60 amp breakers? Thanks.

Same situation, same question. My plan is to run them at 40A off of one 50A breaker and make them power share

 

[GrokTime]

I have spent a lot of time trying to figure this out and asked questions in other forums. I could be completely wrong on this and request anyone who knows more to chime in.

However, the best I can figure out is that as of now (January 17, 2024), Tesla says to run each Wall Connector off of its own breaker, whether that is in the main panel or a sub panel.

For example, if your main panel has 60 amps of capacity, Tesla still says to install two new 60 amp breakers. This would be very bad if you install two 48 amp chargers that don't power share. This would also be bad if you install two Tesla Universal Wall Connectors and don't set them up to power share.

From what I understand the Wall Connectors communicate over wifi (I am not sure if that is your house wife or their own interdevice wifi). They should not draw more than 48 amps collectively. I have been told (but can't find it specifically documented) that if the Wall Connectors lose connection to each other they will each fall back to an overall safe level (24 amps max each in the above example).

From what others have told me this meets code because the devices are being installed according to manufacture specifications and that Tesla specifies it is safe and that they won't draw more power than is safe. Once set up properly the only way to make the two connectors draw more than 48 amps collectively would be to go into password protected settings and deliberately make a change.

On the one hand I think this sounds risky because I am relying on software to maintain a safe power draw. On the other hand if I connect a Wall Connector into a 30 amp circuit I have to rely on software to bring the max draw down as well so what is the difference?

 

[EchoDelta]

I am looking into getting a similar setup. Can you please clarify how the wiring works? I thought power sharing meant that each unit did not have to be on its own circuit? If I only have capacity for one 60 amp circuit wouldn't it be a violation of code to have two 60 amp breakers? Thanks.

To pass code (and what I did) you can have one 60A feeder from the panel into a load center with two 60A breakers.
each beaker then has a 60A feed into the wall connector.

this saves all the 60 amp wiring from the panel, and having to have 60 A of extra current budget in your panel.

When in use, both breakers are on, and wall connectors are configured to have one “controller” and one that is controlled by that.

sorry I didn’t reply earlier, we did an awesome road trip Seattle- Sun Valley just during the cold snap.

 

[GrokTime]

To pass code (and what I did) you can have one 60A feeder from the panel into a load center with two 60A breakers.

Thanks! Can you clarify just what you mean by a "load center"? Is that just a sub panel or is it something else?

 

[EchoDelta]

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Only the lives and ground are needed for the chargers, no neutral. I still used 3/4 EMT conduit as it is the standard for all our outdoor stuff.

You are correct they use WiFi to communicate loads but it has failsafes if there isn’t active communication, so as never to exceed total current. I can’t remember if I read that just the controller keeps working, or they go into dumb 50-50 split mode. They are UL listed.
This is starting also to be more common with Smart panels, etc.

When you plug in your cars, typically the one with the lowest state of charge will draw more than the one that has more charge. I’ve seen this in 25% steps (approx) - 2.9kW + 8.6kW, 5.8+5.8, 0+11.6.
Since our model Y is almost twice as efficient as the Rivian, it means it charges twice the number of miles per hour at the same power, so it gets ahead faster. But the beauty of the system is the set it, and forget it for more than one car.

 

[EchoDelta]

Thanks! Can you clarify just what you mean by a "load center"? Is that just a sub panel or is it something else?

It is essentially a sub panel. Load centers, however, may have simpler installation and code requirements, than full sub panels, and typically don’t have a main breaker for all the loads.
Siemens W0408ML1125U Load Center,... https://www.amazon.com/dp/B00002N5HF?ref=ppx_pop_mob_ap_share

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