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Slow supercharging in hot weather?

MITE46

Member
Aug 26, 2014
185
384
Los Altos / San Marino
its been quite hot in California the last week or so. Still 100F outside at 8:30pm. Supercharging starts out very fast at 120kw the. Very quickly drops to 36kw. Repluging raises back to 60kw then drops to 36kw again. Is this due to pack temperature?
 

MITE46

Member
Aug 26, 2014
185
384
Los Altos / San Marino
So I called the tesla supercharger number and they said that some of the sites are in reduced power mode. Nothing wrong with car nor stations has to do with utility provider.

Hmmm


its been quite hot in California the last week or so. Still 100F outside at 8:30pm. Supercharging starts out very fast at 120kw the. Very quickly drops to 36kw. Repluging raises back to 60kw then drops to 36kw again. Is this due to pack temperature?
 
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cpa

Active Member
May 17, 2014
3,060
3,810
Central Valley
Yes, PG&E has announced that certain ball-busting hot days in the summer will have periodic power reductions in selected areas around the state in order to stave off any potential brown-outs. I thought that this was only for residences and small offices, not commercial or industrial applications like Superchargers. But perhaps in the spirit of cooperation, Tesla opted to permit this reduction at its SCs in PG&E territory in order to be a good corporate citizen. Or maybe it was foisted upon them by PG&E.
 

ABCCBA

Member
Dec 20, 2015
387
234
Somewhere
Most likely, Telsa has negotiated a discounted rate for electricity at the Supercharger locations, if Tesla agreed to curtail usage during Peak Demand times when the utility sends out alerts. This is a very common practice across the United States for utilities to 'Peak Shave' by reducing load rather than having to turn on more Peak Generators to meet a growing demand.
 
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ArtInCT

Always Learning
Sep 2, 2014
1,713
433
Southern Connecticut
A few questions for you....
1) how fast were your cooling fans running on the car during the Supercharge?
2) how warm do you think your traction pack was prior to arriving at the Supercharger?

Is it possible that the car's battery pack was very hot and during the Supercharge the BMS signaled the Supercharger to reduce the flow of kw?
 

efxjim

Member
Jan 18, 2011
231
29
Glendale, CA
i experienced this at buttonwillow several days ago. The logic of slowing down your charge rate does not affect the amount of power used. Each car will just stay longer and overlap the charging of other cars still using the same amount of power. No peak limiting will occur. It was very inconvenient to have to stay an additional 20+ min to charge. I even moved on to the Tejohn charger (the ones with batteries) and the restricted charge levels were still in effect. I rerouted to the buttonwillow charger since the map indicated the Tejohn charger was operating at reduced capacity (coming down the 99). The map did not indicate reduced capacity at Buttonwillow. So that added additional delay. I was the only person at both chargers. Very annoying .
 

apacheguy

S Sig #255
Oct 21, 2012
5,081
1,241
So Cal
Agree that is annoying. Tesla needs to add more power packs so they can buffer during peak usage. Tejon already has battery banks so I am surprised they are throttling.
 
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thecloud

As rhythm raced inside, the ship came alive
Nov 24, 2014
1,772
1,627
Sunnyvale, CA
i experienced this at buttonwillow several days ago. The logic of slowing down your charge rate does not affect the amount of power used. Each car will just stay longer and overlap the charging of other cars still using the same amount of power. No peak limiting will occur.
The goal isn't to keep you from using the same total amount of power. It's to limit the rate at which you are consuming that power at any given moment.

Think of the available power as water flowing from garden hoses connected to a reservoir. A pump is constantly working to refill that reservoir at a steady rate. However, if enough people are filling their water pails from these hoses all at once, and the water is flowing at a faster rate than the pump can replace it, you'll drain the reservoir. So you turn down the valve on the hose, and the water flows out half as fast. This gives the pump enough time to replenish the water that's being used. Everyone gets their pail filled eventually. It just takes longer when there's more demand.
 
Last edited:

jkliu47

Member
Apr 30, 2013
459
74
Glendale, CA
When I was driving up to Reno for the Gigafactory opening this past Thursday I saw on the GPS that Lone Pine SC was showing restricted power. I checked with Tesla Road Service and they confirmed the power restriction was due to weather (excessively hot). So I fully charged up at Inyokern rather than skip it on the way to Lone Pine.
Since I was on the way anyway, I dropped by Lone Pine to check, and yes the power was restricted to less than 60 kW. The temp btw at ~2:30 pm was >115F (!) So its probably a utility restriction. The SC connector handle was HOT HOT HOT.
Today I checked my route home for tomorrow and Tejon Ranch currently shows a restricted power warning. Just in case, I will fully charge at Atacadero SC tomorrow and skip Tejon Ranch on my way home.
 

jkliu47

Member
Apr 30, 2013
459
74
Glendale, CA
At the very least, there need to be clear indications on the Nav (as well as charge screens) when throttling is occurring.

Yes the nav screen shows a different symbol than the normal symbol signifying a SC location. Its also Red but looks more like a traffic restriction sign somewhat like a No Entry sign (with horizontal slash).
 

Electroman

Supporting Member
Aug 18, 2012
6,168
6,244
TX
When I was charging at Waco,TX midday yesterday at 103F, I noticed that the rate never went above 250mph even at low SOC. I have seen 300mph earlier on other occasions at cooler temps, and so it was a surprise to me.

Now I am wondering if it was throttled.
 

MITE46

Member
Aug 26, 2014
185
384
Los Altos / San Marino
A few questions for you....
1) how fast were your cooling fans running on the car during the Supercharge?
2) how warm do you think your traction pack was prior to arriving at the Supercharger?

Is it possible that the car's battery pack was very hot and during the Supercharge the BMS signaled the Supercharger to reduce the flow of kw?

I think there are two issues here...when the fans are on high, yes the charging speed is reduced, but there are times when it is obviously throttled when the fans are not on. I called tesla supercharger line again and they were actually able to tell me which stalls to avoid that were in "reduced power mode". It just turned out that 100% of the stalls at harris ranch and buttonwillow were in the state. This added an additional 1.5 hours to a 5 hour trip.

I believe there were a couple of demand response events during the day, but I didn't think they would still be happening at 11pm at night.

The peak shaving could make sense. Eventhough it's not a peak for the tesla station, it could be a peak for the general area...?

Either way, I thought the stationary storage solutions at the SC are supposed to address this exact issue?
 
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Rocky_H

Well-Known Member
Feb 19, 2015
6,121
7,123
Boise, ID
The logic of slowing down your charge rate does not affect the amount of power used. Each car will just stay longer and overlap the charging of other cars still using the same amount of power. No peak limiting will occur.
Sorry, but this is flat-out incorrect. The biggest problem is that you are using units terms incorrectly. Normally, I won't be a stickler about using terminology wrong, but that's why you're not getting it right in this case. @thecloud also gave a correct explanation on this.

Power is a term that means a rate per second that energy is being used or moved. Watt is the usual term for that (or kilowatt). A Watt is 1 Joule per second. Energy is a different quantity. Energy may be measured in Joules, or as you are more familiar with, kilowatt hours. Notice that you take the power, which is energy per second, and multiply it by the amount of time to get the amount of energy. When you said, "Each car will just stay longer and overlap the charging of other cars still using the same amount of power.", that is not right. You mean the same amount of energy.

So anyway, these peak demand charges that the utilities have to deal with aren't about the total amount of energy. They are about the fastest rate that they are having to deliver it. And slowing down the rate at the Superchargers definitely does reduce those peak power levels.
 

rypalmer

Active Member
Aug 22, 2014
1,379
1,470
Canada
I experienced a lot of throttling coming through Ontario (Cornwall, Kingston, Port Hope) on Saturday. Similar issue: up to 97kW at first, dropping back to 22kW in one instance. The car's AC was not running high and none of the sites were that busy or had me sharing chargers. It was hot but not excessive. My car is new so I wasn't sure if I had an issue but tech support indicated the SCs were operating on reduced power with no further explanation.
 

gaswalla

Model S,3,X.. CT with Austin delivery
Sep 23, 2012
3,302
3,579
San Diego
The lines at California SC this summer have been nasty... combination of more cars on the road, locals being shameless, and throttled charging rates.
 

ThosEM

Space Weatherman
Dec 13, 2013
869
310
Annapolis, MD
I find this to be disturbing; to the point that it has occurred to me that we get what we pay for. This weekend was very hot on the eastern seaboard, and we encountered this each time we tried to charge. It seemed to me that my travel plan was being used against me to limit my juice to that needed for my next charge point and no more. But it had the effect of forcing me to do extra stops when I normally would have passed up some superchargers. I wonder if Telsa are also thinking to use this as a mechanism for limiting local charging, not that I would be upset by that. But I am upset that my road trip charging is being limited so that the businesses I visit while charging can be overly air conditioned.

On the other hand I understand that peak loads do place an unusual load on the grid. But I thought that EVs were a way to address that by charging at night when the load is light. Also I recall that our supercharging was originally to have been offset by solar power generation at the charging sites, presumably by buffering the power with batteries,

This looks like a pretty significant problem for Tesla. Perhaps it's not that different from gas lines on the turnpike service centers in the summer, but it sure does leave a bad taste in my mouth.
 

apacheguy

S Sig #255
Oct 21, 2012
5,081
1,241
So Cal
At Harris Ranch now. Started out fine at 114 kW and held for about 60 s. Then it started tanking fast. Now only getting 58 kW. Is this consistent with others experiencing PGE throttling?
 

apacheguy

S Sig #255
Oct 21, 2012
5,081
1,241
So Cal
Yes the nav screen shows a different symbol than the normal symbol signifying a SC location. Its also Red but looks more like a traffic restriction sign somewhat like a No Entry sign (with horizontal slash).

Definitely not full proof. I'm at Harris and there is absolutely no indication on my screen that the SpC is throttling. Very frustrating.
 

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