Which Install Makes The Most Sense?

[gnuarm]

What outlet would you suggest Tesla use to draw 32A continuously? The 240V outlets you’ve seen in homes were 30A circuits for dryers, so a car could only draw 24A continuously. I thought you were all about charging faster.

That's not the question. The question is why did Tesla cut the current back to 32 amps??? The gen 1 cable would do 40 amps from a 14-50 connector which is an 80% rating. So why cut back to 32 amps for the gen 2???

There is a lot of info available on various charging options and much of it doesn't tell the complete picture. In the end it makes very little difference if I use a mobile cable with a 14-50 plug or I use a J-1772 connector in my home. I can get the current up to 48 amps with an HPWC, but not the 72 amps I've seen discussed in many places.

So which information is right and which is wrong??? I need to keep a log book and track real world data myself.

 

[TexasEV]

That's not the question. The question is why did Tesla cut the current back to 32 amps??? The gen 1 cable would do 40 amps from a 14-50 connector which is an 80% rating. So why cut back to 32 amps for the gen 2???

Do you read this forum too or just post? This question has been asked and answered MANY times since the Gen 2 UMC came out.

There were lots of instances where charging at 40A caused problems even though ideally it shouldn't. Screws not torqued properly, aluminum wire rather than copper, etc. could cause overheating and risk of fire. The firmware was designed to drop back to 30A when it detected a voltage drop but that's not foolproof. Some 14-50 outlets were installed on 40A circuits, which is allowed by code in some circumstances, and the person plugging into it assumed it was a 50A circuit but it wasn't. In Canada they required limiting the UMC 14-50 adapter to 32A a few years ago because of problems like these. There's not a huge difference in charging at 32A rather than 40A, usually it's what time the car finishes charging during the night and doesn't really matter, but it's much safer. Especially as the car goes mass market as you keep pointing out and not all new owners will be aware of this stuff-- they just want to plug in and assume it works safely. If 32A charging is inadequate for your situation, install a Wall Connector for higher amp charging.

 

[gnuarm]

Do you read this forum too or just post? This question has been asked and answered MANY times since the Gen 2 UMC came out.

There were lots of instances where charging at 40A caused problems even though ideally it shouldn't. Screws not torqued properly, aluminum wire rather than copper, etc. could cause overheating and risk of fire. The firmware was designed to drop back to 30A when it detected a voltage drop but that's not foolproof. Some 14-50 outlets were installed on 40A circuits, which is allowed by code in some circumstances, and the person plugging into it assumed it was a 50A circuit but it wasn't. In Canada they required limiting the UMC 14-50 adapter to 32A a few years ago because of problems like these. There's not a huge difference in charging at 32A rather than 40A, usually it's what time the car finishes charging during the night and doesn't really matter, but it's much safer. Especially as the car goes mass market as you keep pointing out and not all new owners will be aware of this stuff-- they just want to plug in and assume it works safely. If 32A charging is inadequate for your situation, install a Wall Connector for higher amp charging.

What screws not torqued? On the outlet or the cable? I don't see how lowering the current will solve a problem with a faulty connection. A bad connection can cause problems even at 32 amps. Aluminum wiring is not a problem that has anything to do with high current. It can be a problem if not installed properly again, at nearly any current. Houses burn down from faulty aluminum wiring installation... again not a Tesla problem, an aluminum installation problem.

None of the problems you list have anything to do with the UMC. If Canada required the UMC to be limited to 32 amps on a 50 amp connection because of installation problems with the connectors they would appear to be pretty ignorant of the problems.

Where is any of this documented? I'd love to read about this from the source rather than second, third, fourth hand.

 

[Rocky_H]

Some 14-50 outlets were installed on 40A circuits, which is allowed by code in some circumstances, and the person plugging into it assumed it was a 50A circuit but it wasn't.

None of the problems you list have anything to do with the UMC.

Yes, this issue very specifically does. If 14-50 outlets were installed as 40 amp circuits, they likely would be using smaller wire, like 8 gauge romex or even 10 gauge separate wire in conduit. These are not even all that unusual and are still code-compliant. The older UMC would be drawing 40 amps out of 40 amps--100% capacity--for many hours on end. The wire is not rated for that kind of heat load, because you are supposed to be only using 80% of the capacity. The breaker very likely would not trip, but that can be dangerous for the wire heating. But people plugging into that outlet might not know the type of circuit or wire size behind it, like if it is at a friend's house, or if they bought the house and moved in and found that existing 14-50 outlet there, assuming it was a 50A circuit.

So using 32A no matter what is the "lowest common denominator" that safely covers whether they are 40 or 50 amp circuits. That way regular people can just plug in without having to know or research what is behind the outlet, what gauge the wire is, etc. etc. that they shouldn't have to know about.