mtberman

I know nothing about electricity but I believe this is attributable to plug and installation. VW/Aud programmed its EVSE under the mistaken presumption that the average US 14-50 outlet is capable of handling EV charging.

The electrician certified by our utility company was expensive, but he chose a an industrial type plug and housing. He said you have to do everything precisely, torque bolts, etc. As others have said, the connections carry high loads for hours and it seems like heat wants to build up wherever it can.

ThomasW

That second picture shows the ground wire failing. In many cables (and it appears the same for this one), the ground wire is of a smaller diameter. So if there is a fault in the EVSE that instead of using the neutral now sends 50 amps down the ground wire, it will burn through. The breaker will probably only trigger if the 50 amps are exceeded unless it is a GFCI. The heat build-up may have caused the black wire and the outlet to melt as they seem close to each other. Obviously, this is all speculation as it is difficult to tell without a closer look. But for this reason, I installed a GFCI circuit breaker and used a wire with a full-size, 6 gauge ground wire so that it will be able to handle the full 50 amps and beyond that, the breaker will trigger.

BSaun

We received the notice to bring in the "Portable" charger so that Audi could default it to 50%. Our outlet was wired with 6 gauge wire (both legs and the neutral and ground are 6 gauge) 50A breaker and Nema 14-50. Breaker never tripped. I thought, how could there be a problem after owning the car for years? If a lug nut was "loose" wouldn't I have had this issue years ago? Is it possible that the car drew too many amps? It appears that I'm not the only one with this issue. Is it odd that others have posted a similar photo? Is it possible that the EVSE is bad? An electrician is being sent out and thinks its the lug being loose. I'd like to see how many amps each leg is drawing when charging once fixed. Will also ask dealer to replace EVSE...more to come.

SDakota

Given how important it is not to overload one's wiring, I'm surprised how little information Audi supplies with its EVSE. Here is what appears in my owner's manual:



At least they disclose the maximum output of 9.6kW at 40A on a 240V circuit, but they don't disclose what happens at the 50% setting on a 240V circuit or what happens at either the 50% or 100% settings on a 120V circuit. Nor do they provide much guidance about when to select 50% vs. 100%. The worst omission is that they don't disclose how important it is not to exceed 80% of a circuit's rated Amps.

From my own observation of kW delivered to the vehicle, here is what I think happens at various settings. Someone please correct me if you think this is inaccurate.

Assumed Audi EVSE Specifications
240V @ 100% = 40A = 9.6kW = 8.6kW delivered to the vehicle after efficiency losses
240V @ 50% = 20A = 4.8kW = 4.3kW delivered
120V @ 100% = 9A = 1.08kW = 1.0kW delivered
120V @ 50% = 6A = 0.72kW = 0.6kW delivered before charging stops due to power dropping below 880W as mentioned in the manual

By not disclosing the actual specifications at 50% and 100% settings at different voltages, it seems that Audi is trying to simplify charging. Instead, I think they complicate it and introduce additional risk. For example, if someone rewires their 30A dryer circuit with a 14-50 outlet, what stops them from plugging in the Audi EVSE at 100% and overloading the circuit? EDIT: See post #64 below for an example of this on a 40A circuit.

I assume that's why there is a TSB to change the default setting on the Audi EVSE to 50%. But if someone plugs the Audi EVSE into a 120V outlet on the default 50% setting, they will be surprised to discover that the vehicle won't charge at all. And if they plug it into an old 10A circuit and set it to 100% as recommended in the manual for any circuit less than 200V they risk a fire from exceeding the recommended 80% limit for continuous loads.

On a side note, the Audi EVSE is terrible for Level 1 charging. Audi apparently limited it to 9A at 120V, which is too high for an old 10A outlet and is 25% lower than 12A that could safely be used with a modern 15A outlet. Audi does its customers a disservice by not disclosing the EVSE's specifications at various settings and by not emphasizing the 80% capacity rule for Amps.

No doubt early adopters can figure all of this out, but the charging process should be more clearly explained for mainstream EV owners because these cars are great and understanding the charging process shouldn't be a hurdle.

BSaun

Charging at 100% is important to us as we have hourly pricing..some days its high and some days its less than free...

mikem33

Audi's cables are not good. I noticed this when I installed my 220V socket.
I had two chargers, a ChargePoint and the Audi one, both at 40A. The Audi cord would reach ~80C temps within 15 or so minutes, measured with a FLIR IR camera; the chargepoint cord, on the same outlet, ran about 55C. Ambient in the garage was ~20C. I decided arguing with Audi wouldn't get me very far and I wanted the scheduling ability of the ChargePoint unit, so I installed the ChargePoint unit and shelved the Audi charger; I carry it in the car for 'emergency' situations, but I don't consider it a safe unit to use on a regular basis.

Given Audi's recent recall to force the default charge current to 20A, this must be a common issue.

Other posts are attributing the cable melting to excess current being pulled by the car; this is entirely possible and seems to make sense for some of the cases. In my case, the car showed it was pulling about 8.5KW with both chargers, which is in line with 40A/220V with a 5% loss from EVSE to car.

Bill33525

Had exactly the same observation with my '19 Audi charger measuring more like 150F, here in Fl the garage can be in the 90s so that may have had something to do with it. I ran a small fan on the plug before getting the CP Flex Home charger which ran cooler. Tried a Cooper outlet which didn't make a lot of difference. Never had any meltimg anywhere however. Always suspected the Audi plug had inferior metal on the plug prongs.

ervikingo

Mine did the same today. 2019 eTron, 6 ga wire, 50 amp breaker (tripped!). Replaced outlet, breaker and cleaned plug. Fingers crossed, has been plugged for the last 30 minutes

Bill33525

BTW; the charger on MY21 car runs cooler than the MY19 charger. May want to get a new 240V pigtail with the 14-50 plug from a MY21 car.

sor

I think it should be reiterated that overheating has little to do with tripping, it has to do with resistance. You can easily have a 50A circuit and melt things with 10A of current over a loose connection.

I once had a 100A breaker feeding a subpanel and the breaker was hot as hell. Total of all breakers on the sub is much higher, so my initial reaction was to upgrade the cable and breaker to the subpanel, but after tightening the screws on the wires for the breaker, I found them quite loose and tightening completely resolved the heat issue.

Resistance can happen at the prong in these outlets, or it can happen where the wires are inserted and screwed down. Or it can happen with a weak spot in the wire, or the wrong wire gauge used.

With the amount of power going through these they tend to vibrate microscopically, and if the screws aren’t torqued to spec they’ll eventually rattle loose. My conduit hums when my car charges. I hate to say it but I don’t think I’ve ever seen an electrician pull out a torque screwdriver, though I imagine/hope many do.

Also possible in a case or two here that the ground wire touched a hot or something else.

Worth noting that it seems that the enclosed box wiring is doing it’s job at keeping fires from starting. The code is the way it is to allow for failures to happen in wiring and contain those failures.

For me this is one of the advantages of hard wiring. Less opportunity for resistance/weak connection.