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Charging multiple EV’s at home

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PoorPilot

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So if you already have a Tesla HPWC installed you'll just charge your Rivian by using an SAE J1772 adapter all the time on one of the charging cables? Any difference in throughput when charging via SAE J1772 adapter?
Yes, technically I could do this, however I wouldn’t be able to charge both vehicles at the same time and the placement of 1. The charging unit in my garage is setup for rear charging (Tesla) and 2. The Rivian charge port is located pax side front (completely opposite side of my Tesla).

I’ve been throwing the idea around to my electrician to find the best solution, so we’ll see.
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I built my new house after having already bought a Tesla Model S P90D. I knew I would eventually be driving two electric vehicles, so I had the new house wired with a 50-amp line (for the Tesla) and a 100-amp line (for a future car with faster home charging capacity) in the garage. I had 400-amp service put in the house so that I could charge at maximum Level 2 speed simultaneously on each line.
 
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I’m not building a new house anytime soon, but thanks, I think.
 

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You asked how people were dealing with charging multiple vehicles at home. I responded with what I did when I built, but the same thing could be done in existing construction. If your existing panel doesn't have enough amperage to handle the necessary circuits, the panel can be upgraded. That can be expensive, but it's the only way to charge two vehicles simultaneously at full Level 2 speed.

I think you need some extra capacity in the circuit to avoid tripping the fuse. That is why Tesla recommends a 50-amp line for charging at 40 amps and a 100-watt line if you have the dual charger which draws 80 amps.

If you plug two cars in at once to a line that doesn't have capacity for both cars, they may each try to draw as much current as the line provides, thereby tripping the fuse. If you plug two 40-amp cars into one 50-amp line, I doubt if the cars will know to draw only 25 amps each. I could be wrong, but I'd check with the manufacturer before trying it.
 

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I don't even have one EV yet. When I get the Rivian, it will be my only vehicle. I am building a 24 foot "Adventure Home" that will be 100% off grid electric. It will have 3,500watts of solar, and I am hoping that I will have about 10kw per day of extra energy to charge the Rivian. This will give me around 20 miles a day of range unloaded, and maybe 10 towing the house. My goal is to have zero energy expenses.
A while back I was looking at earth homes, they build them in the ground using old tires, straw and other recycled materials. they look odd but a home that is in the high desert can operate with no AC or heater and the temps stay in the 60s range temperature
 

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Thanks. $1500 seems a little steep to split a 40amp circuit though. I’m going to talk to the Rivian folks this weekend and then my local electrician about some different options for my garage. We’re planning an addition, so I might be able to tie everything in together and upgrade everything at the same time.
 

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Probably cheaper to buy another HPWC and use an adapter as suggested. Fun fact - HPWC is not a charger. It stands for High Power Wall Connector.
The second HPWC can talk to the first and limit total power drawn by the pair to a setting you choose. It should be connected to the same circuit and placed in a location convenient for charging the second vehicle.
BTW if you back the Rivian into the garage it solves the "opposite corner" problem.
For a 50A circuit you can draw 40A continuous. At 240V that is 96 kW into the vehicle charger. Assuming 95% efficiency that is 9 kW into the battery. So the 180 kWh battery could take 20 hours to charge. Actual charge time depends on how many miles you drive each day (assuming you come home) and the efficiency of the car. 180,000 Wh / 400 mi (Rivian's numbers) means 450 Wh / mi.
 
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Probably cheaper to buy another HPWC and use an adapter as suggested. Fun fact - HPWC is not a charger. It stands for High Power Wall Connector.
The second HPWC can talk to the first and limit total power drawn by the pair to a setting you choose. It should be connected to the same circuit and placed in a location convenient for charging the second vehicle.
BTW if you back the Rivian into the garage it solves the "opposite corner" problem.
For a 50A circuit you can draw 40A continuous. At 240V that is 96 kW into the vehicle charger. Assuming 95% efficiency that is 9 kW into the battery. So the 180 kWh battery could take 20 hours to charge. Actual charge time depends on how many miles you drive each day (assuming you come home) and the efficiency of the car. 180,000 Wh / 400 mi (Rivian's numbers) means 450 Wh / mi.
Thanks for the information. I received an additional HPWC from some referrals with my X, so yes, I could install it in the garage, but as I've found out after I had one installed last year - it's not really needed to charge my X. I could have just used the travel charger after having a 240v outlet installed. With that being said, I don't want to install an additional HPWC (Tesla specific) just to charge a Rivian (even if it means purely using an adapter). This seems like a waste of money to me. I'm leaning towards just installing another 240v outlet in my garage.

Secondly, yes I could back my Rivian into my garage, but then I would still have a cord being drug across my X with a possibility of someone tripping, driving over it. Plus, backing into my garage would prove to be a pain due to specific angles and the proximity of a parking pad next to the garage where I keep another vehicle. Without getting into schematics of my garage or a specific layout, I'm going to talk to a contractor and electrician to see what my options are.
 

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FWIW I am thinking Rivian or Model X. I'll add another Nema 6-50 outlet in my garage like I did for my Model 3.
I route the wiring thru my attic and mount the outlet to a vertical 2X6 screwed to a beam in the attic and long enough to hold the outlet, and a bike bottle holder for the EVSE.
I bought a gen1 so I could charge at 40A it I wanted to. Pic is of a 'V 1.0' the new one is a little longer and the meter is on the other side and lower do I can read it better. Anyway The middle of the garage is perfect because the 25 ft cord will reach about anywhere. I park the Tesla on the right so it's just a few steps away.

Rivian R1T R1S Charging multiple EV’s at home IMG_20190201_181341[1]
 

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FWIW I am thinking Rivian or Model X. I'll add another Nema 6-50 outlet in my garage like I did for my Model 3.
I route the wiring thru my attic and mount the outlet to a vertical 2X6 screwed to a beam in the attic and long enough to hold the outlet, and a bike bottle holder for the EVSE.
I bought a gen1 so I could charge at 40A it I wanted to. Pic is of a 'V 1.0' the new one is a little longer and the meter is on the other side and lower do I can read it better. Anyway The middle of the garage is perfect because the 25 ft cord will reach about anywhere. I park the Tesla on the right so it's just a few steps away.

IMG_20190201_181341[1].jpg
Great information and thanks for the picture. I was looking into doing something like this, but I’m still bouncing some ideas around as well as upgrading my home’s panel to get the highest charging rate possible with two or more vehicles.
 

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For several reasons, I had my 35 yr old panel replaced. Breakers, rust, Al service conductors, unsecured main breaker...
 
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For several reasons, I had my 35 yr old panel replaced. Breakers, rust, Al service conductors, unsecured main breaker...
I’m basically in the same boat (50+ yrs old) as well as needing additional space for our addition. Seems like a perfect time to upgrade everything.
 

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Our Tesla HPWC 80A is on a 100 A circuit. The small sub-panel has a 50A and a 100A breaker. The 50A circuit is for the NEMA 14-50 connector which is below and to the left of the HPWC. If I set the Model S to charge at 40A I can also charge another EV on the NEMA 14-50 outlet. I have in fact allowed the Model S to charge at higher amperage after the other EV has started charging. Worse case is that the 100A breaker in the main load center will pop. We are planning to charge the R1S from the NEMA 14-50 connector. I have the Model S start charging at 1 A.M. and will likely start the R1S at 4 A.M. By that time the Model S will be well into its tapper down and not drawing much amperage.

Rivian R1T R1S Charging multiple EV’s at home 004.JPG


Rivian R1T R1S Charging multiple EV’s at home 20191122_192453
 

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From your main panel you have a 100A breaker that feeds a sub panel with a 100A breaker and a 50A breaker?
The HPWC is on the 100A sub panel breaker and the NEMA 14-50 is on the 50A sub panel breaker?
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