Video: Here’s How a Tesla Superchargers Gets Tested


Ever wonder how initial tests are conducted on newly installed Tesla Superchargers?

Guts of a Supercharger

Guts of a Supercharger

Wonder no more.  Here we present video of how the testing gets done.  Believe it or not, an actual Model S is used for initial testing, but power is turned down (way down to only 20 kW) just to make sure that no damage is done.

Here’s the description posted with this video:

“Well, It’s finally done! The VERY FIRST, TESLA SUPERCHARGER STATION IN WISCONSIN! Timing is everything! Met the guys doing the build that were in my previous supercharging video, as well as a few others. Helped them test each station. They took lots of measurements, thermal readings.”

Oh, the video shows some of the Supercharger “guts,” which we think haven’t been on display before, so that’s of interest to us too.

(big thanks to Kman Auto for putting this video together)

Categories: Charging, Tesla


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52 Comments on "Video: Here’s How a Tesla Superchargers Gets Tested"

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Hmmm…driving and video recording at the same time. Brilliant!

With your kids in the car no less. Distracted driving 101.

Gosh, that wiring looks really small! Hard to tell but looks like the power coming from the whitebox is #2, and the paired cabling looks to be around #6. Normally this would be good for 115 amps, but they put, what? 322 amps through these things? I’m ignoring all the other code violations here – hopefully they’re put a distance from any structures.

But man, I’ve said in the past Tesla likes to run things hot, but I had no idea the wiring was so skimpy. Jeez.

In the video, the guy mentioned pushing 232V through the line. If Tesla charges at a higher voltage (e.g., over 300V to match pack voltage*) then the smaller wiring won’t be so much of a problem.

* Does anyone know the pack voltage for a Model S?

Sorry Aaron, Thats dead wrong. 322 amps causes the same amount of cable heating, no matter what the voltage. Since the resistance of the wire changes at .00323 * the temperature degree change above 75 degrees centigratde, its easy to see the cable dissipating 7.84 times the amount of heat it is designed to carry, and with a rapidly increasing temperature of the cable in the SealTight pipe greatly increasing the resistance, it will be dissipating ten times the amount of heat the wire was designed to dissipate.

As I say I’m not perfectly sure about the wire sizes, but the main wire looks like about #2 or #1, and the paralleled cable conductors look like about #6.

Maybe Aaron was getting at the fact that P = V * I, so if the voltage is increased, less current is needed to get 120kW of power.

Wasn’t referring to that… Was referring to the Tesla S drivers who said the 85kwh batteries draw 322 amps. And regarding the 60 amp draw, to get 120 kw that would be 2000 volts, per your formula. I don’t think so.

Doesn’t parallel wiring cut the amperage per wire in half?

Exactly, but if the flexible cable is #6, and depending on the insulation on the wire, which looks like plain rubber to me, then its good for around 50 amps if its 60 deg C rubber. (Some of these cables, like what was supplied with the original volt, are good for 105 deg C when dry), so 2 of those wires in parallel would be 100 amp capability. A bit meager if you draw 322 amps.

So the question is, does anyone know for sure what at least some of the cabling is? It might be labeled on the Supercharger Connecting cord going to the vehicle. Anyone ever bother to look? Certainly there are enough people here who have personally used a supercharger by now.

I looked at the video flick frame by frame in high def, and unfortunately I couldn’t see anything indicating the size of any wires or the size of the sealtight flexible conduit.

Yes, Bill Howland, I’m sure Tesla hasn’t got a clue what its doing and using substandard wiring. if only they had asked your advice!

Yeah i know it seems presumptuous, but I’m just giving my opinion. It goes with growing pains from the Roadster I own.

And I’m sorry if it offends people, but in my opinion the universal mobile connector on the S’s attachment plug runs too hot for my taste. A friend who is using the roadster’s UMC (I never purchased one) was on his third one before he had HAD IT and bought a High power connector.

Your comment, Chris O, was not only misinformed (there are code violations here and that is an objective fact), but it is just another , excuse me, Silly comment of someone who thinks they are expert because they’ve heard people talk about ev’s before, but otherwise have no expertise in the field. I’m trying to deduce if there is a problem or potential problem here, and you offer nothing to the conversation if you can’t add any factual information to the discussion.

So I’m sorry -> unless you have qualifications to make a more informed opinion than mine, or added factual information, then it is in fact you who is being the presumptuous one..

Don’t know about code violations or not but thought low voltage terminations are supposed to be in a separate compartment. Also, the pipe clamps as strain reliefs make me nervous if they are a long term solution.

Sure doesn’t look like those are #6 (0.162″) when looking at them next to the low voltage wires.

I have been using the Model S UMC solely for charging on a dedicated 14-50 outlet with no issue. If I use the max 40A, there is some slight warmth to the touch but I have no need for the charging speed is I typically charge at 20A and you can barely tell a diffrerence from ambient (in South Florida).

It’s not that easy to say without much for scale, but based on the little terminal block and the lug sizes, I’d say those wires are MUCH bigger than what you’re suggesting – my guess was more like #00 on the upstream side and #2 for the paired wires.

Well, the lugs look small and cheap, and the SealTight doesn’t look that large, size comparison can also by gleened by looking at the pilot wiring. Other thing is the outgoing cable has to be small enough to fit into the relatively small opening on the model S charge connector. If they included the legally required bushing at the attachment point, it would have been easier to guess..

I agree looks like parallel wires are at least #2 (1/4″ dia) but hard to tell. There are pictures elsewhere on the web of the wiring compartment that give an idea of its size. I think it is about 12″ high.

Seriously? Violations? Do you think they never had inspections? Armchair warriors!


It’s ridiculous to pretend to know better than the experts.

Yeah, there are violations. Just ask any Electrical Inspector and you’ll be surprized. The Electrical Inspector is the only one that matters here.. There is no information on the Tesla supercharger nameplate indicating the current actually supplied. I believe the ‘full load continuous current’ was 160 amps, if memory serves. An inspector not familiar with the model S product would have no idea that the car actually charges at 322 amps.

Since the supercharger nameplate is for two stahls, the unitiated may think that if the ‘full load output’ of the sc is say 160 amps, then 80 amps are delivered per car. #2, and 2 – # 6’s are adequate for that.

The nameplate rating on the stickers in the back of every supercharger is 210A continuous for the DC cable.

I doubt all the inspectors for the locations they have so far would have missed undersized wiring. What you suggest might sound plausible if they only had a handful of stations, but they have too many now for that claim to make sense.

I stand corrected: 210 amps… So that would be 105 amps per stahl. I don’t see anything on the nameplate that would indicate that a typical car charging would draw 322 amps. My point JakeY is how would an inspector know that? If I just read that nameplate out of the blue, I’d think the thing put out 210 amps and that would be it… No?

Yes lots of them are around now… Is it that the 322 amps is drawn for only a 15 minute period ? Perhaps Tesla has ‘optimized’ the size of wiring such that the battery is charged before the wiring gets too hot. In any event, I bet the Wisconsin Superchargers last longer than the Arizona superchargers. Heavy usage will prove it.

Seriously?! You are saying the thicker conductors (on the right side) are only a 1/4″ in diameter (the conductor, mind, not including the insulation)? The Jubilee clips (hose clips or whatever you call ’em in the US) bands on the left of the picture are at least 8mm (0.31″) in width and using that as a guide the bigger conductors are at least 2/0 if not 3/0 (190 or 240A maximum for power transmission) according to and the smaller, paired conductors look at least #3 or even #2. So don’t fret!

Admittedly I may have misjudged the size of the wiring Martin. I would like to know if anyone has read any markings on the cable while using a supercharger. The cable itself only looks the same size, or possibly a smidgen larger than the adapter cable for my roadster, which is 2 – # 6, 1 – # 8, and 2-#16’s. With 75 deg C termination limitation, US practice would be 175, 200, and 230 amps for 2/0, 3/0 or 4/0, respectively.

Great job. Yep it has been cold up here in the upper US. Great winter for Tesla testing in the cold, consistently below zero here in Mn this winter.

So the Supercharger is AC?

No, it is not AC. That is not really the ‘guts’ of the supercharger apparently.

Pulsating DC I would guess. But its the ‘guts’ as far as the driver is concerned, and as far as insideevs is concerned. I would imagine curiousity seekers are disappointed that all the white box stuff is locked up.

Christopher Allessi II

No, those are not the guts of a Supercharger. The actual supercharger is in a Cabinet about 20 ft away behind a Wooden Gate & Fence. That is the inside of the Kiosk. The actual supercharger itself stands about 7 ft tall, has a massive cooling fan on it (liquid cooled), and all wiring goes underground through conduit. The current 120kW superchargers consist of 12x10kW chargers. The same ones that the car itself uses, only their are more of them and they are stacked in parallel. The Supercharger takes the 3phase power from the utility, and dumps DC power directly into the battery pack allowing charging at insane speeds.

Each supercharger location is inspected multiple times. First inspections from the Local Electrical and Building Inspectors, then a Tesla Inspector, a UL inspector, sometimes a SquareD inspector (they provide some of the electrical). Then another guy comes out who I cant remember off the top of my head (from New York) I dont have his business card on me at this moment. He does the final inspection and calibration.

Definitely distracted driving. A point on the “guts of a supercharger” picture. Actually, that looks like just the charge station wiring with the connector to the car. The actual superchargers are stacked up inside the fenced-in area. Those are the real guts.

Get the kid outta there! I have 2 myself but get out of my way and don’t touch things!

Nice, but do not drive and shoot a video. Think about your kids safety and other drivers safety first. Bring along your wife or some else to be in charge of the camera next time.
Safety first pls. it only takes a second to get everything wrong and you will regret it rest of your life if you survive.

Keep it safe pls.

I don’t think he’s being unsafe here. He is straining himself but if you look in the beginning he is continuously scanning his surroundings, paying good attention, driving slow with good distance margins. He is very alert.
This is not the dangerous sort of behavior. It’s the relaxed stuff that’s dangerous. Airhead girls who text like the Kardashians.

Yeah, I do the same when driving drunk (scanning surroundings etc). Completely safe.

Christopher Allessi II

I stay alert. When shooting video while driving, Driving comes first, Camera falls, big deal I’ll get it later, driving comes first.
That, and on a liter more humorous note, I am driving a Tesla, so I’d have to drive through 2 concrete walls, and then hit a large tree while traveling at over 100mph, and even then, we’d only get mildly bruised.

Judging from the terminal blocks (muffs) size in photoshop the cable is around 15.5mm wide which is 0000 or bigger depending on insulation thickness. So probably not critically undersized.

That’s a point Dan, Another clue might be the number of conductor strands….. As to Koz’s point about the thickness, rubber insulated conductors have a lot of insulation, so the diameter of the insulated wire is much larger than just the copper.. You can see that by the crimps at the terminal strip lugs. That’s why I put it out to model S supercharger users as to if they’ve ever read the connecting cable that attaches to the car. It only looks a smidgen bigger than the adapter cable I have for my roadster, which has 2 #6, 1 #8, and 2 – # 16 wires in it. I know the size of my cable because the contents are printed on the outside of the cable, as they also are on the Chevy Volt’s cable. To Mustang_Salad’s point and Koz’s point that the wiring is either 2/0 or 4/0, its conceivably that big, and If so I’ve mistakenly judged its size. But that’s still only 175 amp or 230 amps rated since the terminations are still standard 75 deg C limitation. To Koz’s point about low/high seperation, you’re right, however if they are spacially separated in “equipment Approved for the… Read more »

At the crimp you can tell the insulation isn’t thick so that’s at least 4/0 cable coming in.
The outgoing double cables do appear to have less copper. I’d say 7-8mm diameter copper so probably 1 gauge. Certainly not 6. I’m guessing 330A through such a pair will make them warm but nothing problematic.
I can ask the guy. He seems to live for going to superchargers so he can tell if they get warm. Two 6 gauge wires would get very hot with 330A.

He said: “The kiosk whip does not heat up, slight warming where the cable connects to the car.”
That doesn’t sound problematic certainly.

Thanks for checking that out Dan.

Christopher Allessi II

Hello, I Appreciate my video being posted (I’m The K-Man).

The feeder wires from the Supercharger to the Kiosk are at least 00 if not 000 Gauge Wires. More then capible of carrying the amperage required.

The Wires from the kiosk to the car are a pair of stranded wiring. I do not have exact size specs, but they appear to be 1/2 the size of the feeder wires. Their are 2 of those wires for positive and 2 for negative. Their is no noticeable heating of the Cable from the Supercharger Kiosk to the Car. The wires remain ambient. As my car is limited to 105kW charging speed, I have checked wire temps with a non-contact thermometer, and the head increase was about 3 degrees F at 105kW draw compared to no charging.

Christopher Allessi II

Oh, forgot to mention, I believe the Sheathing on the wires is Silicone, not rubber. And the reason for splitting the conductors and using much higher strand count was to increase flexibility of the Supercharger Kiosk Whip. And even at that, it is extremely hard to flex. Their is NOTHING undersized about the Superchargers.

Christopher Allessi II

2×6 AWG would yield 80 amps sustained. The HPWC charger already puts out that much.

They may be More than capable, but NEC limits the current on a 3/0 CU @ 75 deg C termination to be 200 amps. I’m sorry, but those are their rules, not mine. That probably explains the 210 amp nameplate, so as not to get the inspectors nervous.

That said, I enjoyed your video.

I believe the cable is at least 4/0 and I hear that those standards are rather conservative, depending on application.
And they must be since the copper amount in the whip seems to be less and doesn’t get hot.

So if a 60 kwh model draws 322 amps does a 85 kwh model draw the same or does it draw even a larger current?

NEC standards conservative? They’d be glad to have you categorize them as that. They also, incidentally have the force of law in about 99% of locales in the US.

The primary concern of course of any inspector would be the Square – D QED-2 switchgear behind the chargers. Speaking of which its seems Xcell energy has much more stringent requirements regarding the switchgear only than the utilities in my area. 3 switchgear bays plus an additional ct cabinet seems to inidcate a single main device, and non-transformer pad metering. Since the service isn’t likely over 800 amps, my utility would not require the main device, nor off-transformer metering, thus elminating the ct cabinet requirement, nor the single main, since my utility allows hot-sequence.

“…The wires remain ambient….”

That’s physically impossible. If true, there would be no need for the 75 degree centigrade termination rule. Even though they call this thing a “supercharger” does not mean the have superconducting conductors in it.

It may have a silicone outer covering, but the individual wires inside look rubber insulated or else crosslinked polyethelene. But not having seen one i’m just guessing, as everyone else on here appears to be also since no one has given definitive information as to the exact contents.

I’m sure all the SC’s are within spec and code. If not, then shame on all the inspectors for passing them.

With all of Tesla’s SC’s and none have failed to anyone’s knowledge then consider it done.

If you disagree, then your beef is with the series of inspectors.

I’m not going hard on the inspectors. There primary concern would be the QED-2 Square-D (Schneider Electric) Serivice Entrance equipment (The 3 grey cabinets behind the supercharger bays). In a previous post I speculated Tesla may have ‘optimized’ the heating of the wiring with charging of actual cars such that the charge gets finished before there is any problem. It would be much more educational if someone could definitively state what the wiring sizes are exactly, but, its true that there does not as of yet seem to be a concern. Guessing only gets you so far.

I am much more familiar with the QED – 2 switchgear behind the superchargers, therefore I speculated what would be ‘Typical’ inside these devices for this amount of power supplied by the Utility. After all, the Service Entrance is much more ‘plain Jane’, since, to the utility, The ‘Supercharger Complex’ is just another typical load that must be serviced.

One legitimate ‘beef’ I have is that the output seems to indicate 210 amps. What is listed on the nameplate is technically true. Again, there’s some legalese going on here, but its been proven here on inside ev’s that a 60 kwh can draw 322 amps. My question is, what is the peak indicated current of a dead 85 kwh battery model? Is it 322 or is it more?

An inspector would not be faulted if he read the supercharger nameplate and walked away thinking the unit could supply only 210 amps intermediate term. Nameplates are usually considered sacrosanct.