Tesla Supercharger attendant suggests throttling occuring

[Advicebox]

I stopped by the San Mateo supercharger today and chatted with the Tesla rep that's assigned to the location. It was like a full service gas station btw, I pulled in, and there was a Tesla capped gentleman putting the charger into my car. So we got to talking and I asked why this time I was getting around 250 miles per hour charge, and last time I was there I only got around 125 miles per hour charge. BTW, in Tahoe I've gotten up to 360 miles per charge so I was curious why all the different numbers.

He basically confirmed tha Tesla throttles customers that are topping off. If you head to the supercharger with an 80% full battery, you are effectively using the Supercharger to save charging at home. Tesla knows this and throttles the speed at which you can charge to discourage this behavior and save energy/spaces for traveling customers. Today I showed up with 1/3 full, aprox. 100 miles left and received a strong 250 miles per hour charge.

He also confirmed that the superchargers are capable of up to aprox. 370 miles per hour.

I know there are a lot of threads out there focused on the physics of charging an almost full battery, but the entire conversation today was around policy and not science.

Anyone else aware of this? or have had similar conversations with Tesla directly?

 

[gaswalla]

That's not throttling, that's the supercharging rate curve. It's even on the Tesla website. The attendants are idiots, not even employees of TSLA apparently.
I actually believe that Tesla has throttled owners, but it really doesn't make business sense since all that does is create a line of upset owners waiting to charge.

 

[schonelucht]

Why is there even a Tesla attendant at the supercharger in the first place?!?

 

[gaswalla]

To discourage local charging and inform folks of Etiquette. They have zero EVI, though. (EV intelligence)

 

[Advicebox]

Why is there even a Tesla attendant at the supercharger in the first place?!?

the San Mateo supercharger is a crowded one, so I'm sure first and foremost it's to hold folks to the 30 min limit where posted. He was a younger kid, probably in his twenties. Very polite, and attentive. Even if he has no EVI as gaswalla suggests, the answers and discussion seem to come from training and not his own assumptions. So whether this was a contractor placed employee, or a Tesla employee, I do believe he was trained by someone to give the answers he did.

Is it possible that the throttling is both science and policy? Some natural throttling, and and some policy enforced reduction?

 

[thecloud]

I don't think most folks are even able to arrive at Harris Ranch or Tejon Ranch with 80% remaining, but there have been multiple reports of throttling at those locations over the past few days. If you're at one of those superchargers, it's really only because you're traveling.

So I wonder whether there are multiple types of throttling going on: a penalty for "topping off" at local superchargers (like San Mateo, Mountain View, Burbank, Fountain Valley, etc.), and a different sort of throttling to reduce overall load on hot summer days.

A question would be whether the throttling algorithm takes my destination into account. If I'm at Harris and want to charge enough to skip Gilroy on the way home, is it going to throttle me hard once I reach a minimum range that can make it to Gilroy and no further?

 

[gaswalla]

The recent reports of throttling appear to be consistently related to ambient temperature - very hot. Thus, the reason may be due to hardware limitations or due to utilities limiting electricity supply during periods of peak demand. This latter scenario seems to be most plausible, especially in California.

 

[WannabeOwner]

Tesla knows this and throttles the speed at which you can charge to discourage this behavior and save energy/spaces for traveling customers.

Seems improbable to me - doesn't a new software-limited 60kWH model charge at "high speed" up to its 100% setting, compared to a non-software limited model that slows down the nearer it gets to full?

I can understand that a user who frequently charges locally and then always drives home afterwards might be identified and "discouraged", but someone who doesn't abuse the system might charge close to home for all sorts of reasons - I'm not actually going home, just happen to be close-to-home when charging and then I'm off somewhere completely different; or I'm going home because there is a medical emergency and I know a) I don't have charge to get to the subsequent destination and b) charging when I get home will be too slow.

 

[PaulusdB]

Please note that the mentioned 'miles per hour' charging speeds are averaged over the charging session.
To understand the dynamics of the charging process better, switch the unit of measure for the battery from 'distance' (miles or km) to 'energy' (kW).
For reasons only known to Tesla s/w development, 'miles per hour' is averaged over the session and 'kW' is not.

 

[Brass Guy]

There are several factors at play here.

The most obvious one is the charge taper. I always thought the "Mile Per Hour" charge indicator was poorly implemented, and should not be an average as it is. People who arrive at a SC at a low state of charge will still see a high number for that charge rate even past 95%, when really it's not charging any faster than a HPWC at that point. Over 98% it's slower than a UMC (actually charging with a UMC tapers then too); but the average will show well over 100mph! (Numbers estimated, but I am being conservative.) I think if the car showed instantaneous charge rate, more people would unplug sooner.

Heat is another great factor, but I doubt it's from the utility; the car will back off the charge rate if the battery is too hot. Do you hear those fans cranking in the front of your car? If they can't keep the battery cool enough, the charge rate will fall.

Then of course there's SC pairing. Enough said about that.

I have a difficult time with the idea of "selective" throttling, and agree it would just make the lines longer and would be a bad idea.

 

[TexasEV]

The Tesla attendant doesn't understand the supercharging taper. Neither do the TMC members who rated the post "informative". It's not informative, it's wrong.

 

[deonb]

Is it possible that the throttling is both science and policy? Some natural throttling, and and some policy enforced reduction?

No. The guy is just wrong.

 

[kort677]

could this be FUD?

 

[Matias]

could this be FUD?

Hanlon's razor - Wikipedia, the free encyclopedia

 

[Vitold]

[...]

I know there are a lot of threads out there focused on the physics of charging an almost full battery, but the entire conversation today was around policy and not science.

It is uncommon in the world of truthiness, but it's good thing when policies are based on science.

 

[AmpedRealtor]

That Tesla employee is an idiot.

 

[ecarfan]

He basically confirmed tha Tesla throttles customers that are topping off. If you head to the supercharger with an 80% full battery, you are effectively using the Supercharger to save charging at home. Tesla knows this and throttles the speed at which you can charge to discourage this behavior and save energy/spaces for traveling customers. Today I showed up with 1/3 full, aprox. 100 miles left and received a strong 250 miles per hour charge.

That person simply does not understand the charge taper curve. They are confused. Tesla does not "throttle customers that are topping off." When you start charging with your battery at a fairly high state of charge, the charge rate is much less than is you start charging with the battery at a low state of charge. This has been explained on Tesla's website for years now.

 

[thecloud]

Yes, it makes complete sense that the "above 80%" case has to be referring to the normal charge taper. I accepted the statement about intentional throttling at face value, and should have given it more thought.

Now, it's always possible the contractor/employee has been told to put it in terms people can understand. "There is a slowdown when topping off your tank, and that's intentional" might be easier to grasp than explaining why it's necessary to protect the battery. Maybe they should be using the glass-of-water analogy, where you pour more slowly as the glass fills up so no water gets spilled.

 

[TexasEV]

That Tesla employee is an idiot.

I don't think the idiot is a Tesla employee. On another thread someone said the supercharger attendants work for a valet company.

 

[kort677]

I don't think the idiot is a Tesla employee. On another thread someone said the supercharger attendants work for a valet company.

the valets shouldn't be offering ill informed opinions