Charging 2 tesla 3's in same 50 amp circuit in garage

[georges888]

We have 2 Tesla 3's same model year and my understanding was that both could charge seaprately using the same 50Amp breaker and simulteneousy which worked great for about 1 year then the App "improved" by allowing a choice of charging current per car so I set it to 32amps each and the breaker failed everytime unlike before the new app.
I was told when I purchased the cars that Tesla car are aware of another car in same circuit and compensate according to departure time, charge needed etc and that worked fine for about 14 Months again until we were given a choice of charging current.
I cannot get an answer from Tesla on this simple issue as to what changed and why for 3 months now. Does anyone have the same problem...

 

[STS-134]

I was told when I purchased the cars that Tesla car are aware of another car in same circuit

Absolutely not. Tesla Wall Connectors can share power, and are aware of each other, and will throttle back the charge rate so as to not exceed the total ampacity of the entire circuit if you set them up to do so. You can connect up to 6 of them on a single circuit. But the cars don't know which circuit they are connected to. And by the way, you should never control charging current by relying on the car to throttle back. This is inherently unsafe and can start a fire if the settings get lost in an upgrade. Luckily, your breaker is protecting your circuit, as it should, because you are trying to draw 64A through a 50A breaker. But if that breaker malfunctions, you could easily be dealing with a fire.

 

[E90alex]

What are you using to charge? Wall connectors?

 

[jjrandorin]

We have 2 Tesla 3's same model year and my understanding was that both could charge seaprately using the same 50Amp breaker and simulteneousy which worked great for about 1 year then the App "improved" by allowing a choice of charging current per car so I set it to 32amps each and the breaker failed everytime unlike before the new app.
I was told when I purchased the cars that Tesla car are aware of another car in same circuit and compensate according to departure time, charge needed etc and that worked fine for about 14 Months again until we were given a choice of charging current.
I cannot get an answer from Tesla on this simple issue as to what changed and why for 3 months now. Does anyone have the same problem...

I am not sure how you actually "set this up" but in order for this to work "properly" you would need (2) tesla wall connectors, setup in power sharing. From reading your post, I dont get the impression that you have that. I get the impression that you have a split circuit with 2 plugs and are using the mobile connectors that come with the car.

Does anyone have the same problem...

The "problem" you appear to have is a very unsafe installation, unless you actually do have 2 wall connectors, installed with power sharing. If you dont have two wall connectors, setup with power sharing properly, then you are risking a fire and need to STOP sharing that circuit with devices at the same time RIGHT NOW, and either use one car at a time ONLY, or get power sharing setup properly.

 

[E90alex]

I thought 240V receptacles are supposed to each have a dedicated circuit?

The mobile connectors and cars will not talk to each other to negotiate amperage or prioritize charging. You need wall connectors for that.

You can either
1) switch off everyday which car gets to charge. Or unplug the first one after it’s done before starting to charge the second one.

2) change the outlets to 6-20 outlets with new 6-20 adapters for the mobile connector so they will only draw 16A max each. Although again I’m not sure if it’s within code to have two 240V receptacles on the same circuit

3) run a new dedicated 50A circuit for the second car, but your electrical panel and/or service may not support that.

4) buy two wall connectors installed on the same circuit and set up load sharing between them.

 

[georges888]

When we bough the cars I made Tesla aware of the install and they said it will work fine as it did for over a year. I always have the app settings to 24 amps per car and however how do I find outmore about Load Sharing since it seems I need to install this device (s)

 

[ATPMSD]

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

 

[STS-134]

When we bough the cars I made Tesla aware of the install and they said it will work fine as it did for over a year.

What type of EVSEs are you using and what are they connected to? As I mentioned above, do not rely on the cars to not overload your circuit. If your vehicles dump/lose the current limit settings (which has been known to happen especially after software upgrades), or if someone plugs in another vehicle that isn't configured the same way, you're now solely protected by your circuit breaker, and if it fails, your garage goes up in smoke.

I always have the app settings to 24 amps per car and however how do I find outmore about Load Sharing since it seems I need to install this device (s)

Running 24x2=48A of continuous load through a 50A circuit is also a code violation. Conductors and breakers need to be sized for 125% of the continuous load (or another way of stating this is that continuous load can be a max of 80% of the capacity of the circuit). Charging cars is considered a continuous load, therefore, you're not supposed to run more than 40A through a 50A breaker and wiring.

 

[jjrandorin]

When we bough the cars I made Tesla aware of the install and they said it will work fine as it did for over a year. I always have the app settings to 24 amps per car and however how do I find outmore about Load Sharing since it seems I need to install this device (s)

Regardless of "what worked" sharing a circuit like that is EXPRESSLY against all electrical codes, for a reason. whether "it worked" or not, you are absolutely risking a fire (one that would not be covered by any insurance if they ever saw (2) 240v outlets on a single circuit, and you told them "Oh yeah I use those at the same time).

Using the CAR to "limit the amps" is not something that should ever be done*. Even having the ability to set it in the app is fairly new, and is not a safe way to restrict charging.

@STS-134 has explained a couple of reasons why from a technical perspective, but the TL ; DR version (too long ; didnt read) is " You can not do that, its against code, and you are risking burning your residence down".

(* edit - by "limit the amps in the car should not be done, I mean using that as an attempt to guarantee charging rate. If you have a permitted / proper installed circuit, but want to charge slower than the circuit is permitted / approved for, that can be done. What shouldnt be done is depending on the amps setting to keep the car from drawing more power than the circuit can handle).

 

[georges888]

Thank you for all your input working on a load sharing solution with a Tesla electrical expert soon to resolve it.

 

[Rocky_H]

This is kind of amazing that we have gotten to 10 comments before this, with three from the OP, with still not a single word mentioned about what kind of equipment is being used to charge the cars.

 

[STS-134]

This is kind of amazing that we have gotten to 10 comments before this, with three from the OP, with still not a single word mentioned about what kind of equipment is being used to charge the cars.

Yeah, and I even explicitly asked the OP what exactly he is using to charge the cars and what they're connected to. He seems to have just ignored that part of my post...

 

[RayK]

Yeah, and I even explicitly asked the OP what exactly he is using to charge the cars and what they're connected to. He seems to have just ignored that part of my post...

Maybe a language issue? Seeing as the OP is from the Great White North.

 

[STS-134]

Maybe a language issue? Seeing as the OP is from the Great White North.

The name suggests that his native language may be Français but I was under the impression that most Québécois were bilingual.

 

[hcdavis3]

Maybe a language issue? Seeing as the OP is from the Great White North.

Eh?

 

[Flybyglass]

The installation manual shows ow to share 2 or more chargers same circuit. Page 23 of installation of Gen 3 charger.

 

[miimura]

The installation manual shows ow to share 2 or more chargers same circuit. Page 23 of installation of Gen 3 charger.

No, it doesn't. The diagrams all show individual breakers for each wall connector. Page 23 is a logical diagram, not a wiring diagram.

 

[ATPMSD]

The installation manual shows ow to share 2 or more chargers same circuit.

It shows wiring "options," but sharing is a software controlled feature.

 

[CKwik240]

Regardless of "what worked" sharing a circuit like that is EXPRESSLY against all electrical codes, for a reason. whether "it worked" or not, you are absolutely risking a fire (one that would not be covered by any insurance if they ever saw (2) 240v outlets on a single circuit, and you told them "Oh yeah I use those at the same time).

Using the CAR to "limit the amps" is not something that should ever be done*. Even having the ability to set it in the app is fairly new, and is not a safe way to restrict charging.

@STS-134 has explained a couple of reasons why from a technical perspective, but the TL ; DR version (too long ; didnt read) is " You can not do that, its against code, and you are risking burning your residence down".

(* edit - by "limit the amps in the car should not be done, I mean using that as an attempt to guarantee charging rate. If you have a permitted / proper installed circuit, but want to charge slower than the circuit is permitted / approved for, that can be done. What shouldnt be done is depending on the amps setting to keep the car from drawing more power than the circuit can handle).

Regardless of "what worked" sharing a circuit like that is EXPRESSLY against all electrical codes, for a reason. whether "it worked" or not, you are absolutely risking a fire (one that would not be covered by any insurance if they ever saw (2) 240v outlets on a single circuit, and you told them "Oh yeah I use those at the same time).

Please read your homeowners insurance policy and point out where it says such a loss would not be covered.

 

[jjrandorin]

How Making Home Improvements Without a Permit Can Affect Your Homeowners Insurance Coverage

In many cases, a permit is required for home improvements. Rules on which types of projects require permits vary from

www.rismedia.com

(copy paste from a section)

=====================
Your Insurer Can Deny a Claim Related to Work Done Without a Permit
If you don’t get a permit for a DIY project, or if you hire a contractor who doesn’t obtain a necessary permit, that can come back to bite you if you need to file a homeowners insurance claim. If a project is done without a permit and a mistake causes property damage, your homeowners insurance company can deem you negligent because you failed to get a permit and have the work inspected as required. The company can therefore deny your claim. In that case, you will have to pay for the cost of repairs out of your own pocket. If someone gets injured because of a faulty renovation project, you can be held liable for that person’s medical bills.

Failing to secure a required permit for a home improvement project can also affect the terms of your insurance coverage. The company may raise your premiums or even cancel your policy altogether.
=====================

2 outlets for EV charging on (1) 240volt circuit is absolutely "unpermitted work" as it would never pass any sort of permit to have 2 EV charging circuits on one line, unless there was a disconnect that physically prevented one from working if the other one was working.

Unpermitted modifications that caused a fire could be an insurance fight at best.

Since in another thread, you state " when I worked in the industry...." I would ask you, how did the company you work for deal with unpermitted work that was supposed to have a permit, causing damage?