What happens if I try to charge 2 cars at the same time?

[FredMertz]

I have a Model Y with a Tesla Gen 3 Wall connector. We recently add an E-tron and have a separate Chargepoint Home Flex running off a 14-50 outlet.

They are both on the same 50 amp circuit.

I'm amazed that I can't find the answer to this question easily online, but: If I try to charge the cars at the same time, am I risking damage to the electrical system, or is the only downside slower charging?

 

[buckets0fun]

Breaker should trip.
Protecting your house from the fire that would come from melting the wire inside of your walls.

How did code enforcement / permitting allow this?

 

[jjrandorin]

I have a Model Y with a Tesla Gen 3 Wall connector. We recently add an E-tron and have a separate Chargepoint Home Flex running off a 14-50 outlet.

They are both on the same 50 amp circuit.

I'm amazed that I can't find the answer to this question easily online, but: If I try to charge the cars at the same time, am I risking damage to the electrical system, or is the only downside slower charging?

They are not supposed to be on the same circuit. You cant find a lot of information about that because its absolutely not supposed to be done, and no electrician should have done that. The breaker "should" trip but you are also risking burning your home down.

 

[FredMertz]

Breaker should trip.
Protecting your house from the fire that would come from melting the wire inside of your walls.

How did code enforcement / permitting allow this?

Sorry -- my lack of electrical knowledge showing through.

They are not on the same circuit. One is on a double circuit on my old panel and the other is on a new panel the electrician installed.

With that being said, does anything bad happen if I charge them at the same time? Does the rate slow for each?

 

[Ken_Y]

I don't think anyone can responsibly answer you without knowing the exact set up, load and power coming into the house. Please find a licensed electrician to give you advice.

 

[Rocky_H]

They are not on the same circuit. One is on a double circuit on my old panel and the other is on a new panel the electrician installed.

OK, much better.

With that being said, does anything bad happen if I charge them at the same time? Does the rate slow for each?

That's like asking what would happen if you run your clothes dryer while your oven is on. It doesn't matter, since they are on separate circuits. They will both just run. The only possible but unlikely thing is if the total loads in your entire house gets to be too much, then it could trip the main breaker and your whole house loses power, but that's rare.

 

[jjrandorin]

Sorry -- my lack of electrical knowledge showing through.

They are not on the same circuit. One is on a double circuit on my old panel and the other is on a new panel the electrician installed.

With that being said, does anything bad happen if I charge them at the same time? Does the rate slow for each?

if they are separate circuits (like they are supposed to be), and installed properly, with proper load calculations done to account for possibly using both at the same time, etc, nothing. If you used a licensed electrician, and they pulled permits, you are likely fine. If you didnt, or there was no load calculation, done accounting for the possibility of you using both at the same time, no one really knows.

If you had an electrician do both, you "should" be fine.

 

[FredMertz]

OK, much better.

That's like asking what would happen if you run your clothes dryer while your oven is on. It doesn't matter, since they are on separate circuits. They will both just run. The only possible but unlikely thing is if the total loads in your entire house gets to be too much, then it could trip the main breaker and your whole house loses power, but that's rare.

It would have been great if the new Tesla wall connector for non-Tesla cars would load manage with my original one, but they apparently only load manage with each other.

 

[buckets0fun]

It would have been great if the new Tesla wall connector for non-Tesla cars would load manage with my original one, but they apparently only load manage with each other.

The new J1772 gen3 charger is the same as the gen3 Tesla specific one. In that, they do talk to each other.
But you’ve stated that they’re on separate circuits/breakers, which assuming you had permits pulled for this work, you should not have an issue.

If it were me, I’d call the electrician that installed these and have a chat. The internet is applicable for certain things, not burning down the house isn’t one of them.

 

[FredMertz]

The new J1772 gen3 charger is the same as the gen3 Tesla specific one. In that, they do talk to each other.
But you’ve stated that they’re on separate circuits/breakers, which assuming you had permits pulled for this work, you should not have an issue.

If it were me, I’d call the electrician that installed these and have a chat. The internet is applicable for certain things, not burning down the house isn’t one of them.

I already e-mailed the electrician...

When it was originally released (it appears to no longer be on the Tesla store site), I thought I read that they would not communicate with a Gen 3 charger.

 

[URBAN LEGEND]

I have 2 AUDI E Trons and 1 Plaid. I have 2 dedicated 40a chargers. I can charge any 2 all day everyday plus 1 on a regular 120v. No drop on any of the cars.

 

[Rocky_H]

The new J1772 gen3 charger is the same as the gen3 Tesla specific one. In that, they do talk to each other.

None of that is true. The J1772 wall connectors are based on a Gen2. They were built long before the Gen3 was ever created. Tesla just didn't sell them to the public before now. It has no wi-fi connectivity, so it obviously can't communicate with Gen3 wall connectors. It only has the twisted pair direct wiring for sharing, and it can only share specifically with other Gen2 type units that have the 50A limit, of which two types are available: this J1772 kind or the older ones that came with a 14-50 cord attached, but those are kind of rare.

I thought I read that they would not communicate with a Gen 3 charger.

Yes, you are correct. It can't share with Gen3 ones at all.

 

[jcanoe]

None of that is true. The J1772 wall connectors are based on a Gen2. They were built long before the Gen3 was ever created. Tesla just didn't sell them to the public before now. It has no wi-fi connectivity, so it obviously can't communicate with Gen3 wall connectors. It only has the twisted pair direct wiring for sharing, and it can only share specifically with other Gen2 type units that have the 50A limit, of which two types are available: this J1772 kind or the older ones that came with a 14-50 cord attached, but those are kind of rare.

Yes, you are correct. It can't share with Gen3 ones at all.

I was perusing the Tesla store yesterday evening and noticed that like Eleanor the Tesla Gen2 J1772 Wall Connector is gone. (As in Gone in 60 Seconds.)

 

[Rocky_H]

I was perusing the Tesla store yesterday evening and noticed that like Eleanor the Tesla Gen2 J1772 Wall Connector is gone. (As in Gone in 60 Seconds.)

Yeah, new product that people had been wanting Tesla to sell for a long time--I'm not surprised they sold out quickly.

 

[jcanoe]

Yeah, new product that people had been wanting Tesla to sell for a long time--I'm not surprised they sold out quickly.

Not just sold out; gone from the web page.

 

[roblab]

My two cars charge on 14-50 outlets, on two different 50 amp circuits, set at 32 amps each. The garage has its own 100 amp panel, so if the cars charge at the same time, which is possible, nothing happens. The only other draw in my garage is a freezer which pulls a small amount when it runs, but doesn't seem to interfere with charging. Since I usually charge in the wee hours of the morning, I also set them to start at different times, like 5 hours apart (depends on how much charging I need), and I've never had any problem with charging, ever, since I've owned EVs starting in 2002.

 

[buckets0fun]

Yeah, new product that people had been wanting Tesla to sell for a long time--I'm not surprised they sold out quickly.

Haha. My bad duder.

Buuut…. Not sold out, removed from site.

 

[mmanner]

Sorry -- my lack of electrical knowledge showing through.

They are not on the same circuit. One is on a double circuit on my old panel and the other is on a new panel the electrician installed.

With that being said, does anything bad happen if I charge them at the same time? Does the rate slow for each?

To answer this as others have said, you need to know what else is on your house main panel, and what it's capacity is. If you have a 200 amp main panel, likely ok as long as you heating and air conditioning and hot tub ovens, stove, etc. loads are reasonable. I have a 400amp main supply, 200 to the house, where I have a lot of gas appliances rather than electric. The other 200 amp supplies the garage and hvac systems. I charge my MY at 32amps and MS at 40amps, and that works fine for me. Add it all up and see what you get and think about what will be on at the same time.

 

[Sophias_dad]

To answer OPs question. Other than the minor voltage decrease of a few percent because of lots of load, both cars should charge as if they were charging alone. Worst case should be that your main breaker will trip, and you'll learn that you need to turn down the total current. It is entirely possible that your home's main breaker will be sufficient to handle the load. In fact, the electrician probably shouldn't have let you install both circuits unless its LIKELY that the main breaker will handle the load.

 

[sleepydoc]

So on a related note, you can buy a Tesla to J1772 adapter; if you have 2 gen 3 wall chargers, one charging a Tesla and one charging a non-Tesla via the adapter, will they still load balance?