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If you fast charge, Tesla will permanently throttle charging

There have been a lot of cases in the past where Tesla says one thing, then later it turns out it's something completely different.

I think we're all just trying to get more info. So far you're the first person whom Tesla has mentioned this to. And this would be a big hit to EVERY Tesla driver, so it's a big deal.

The Tesloop taxi driver who drove the Tesla for 200k miles and supercharged daily didn't mention any sort of slowdown. And I'm sure he'd notice. There are multiple drivers on TMC who put over 100k miles on their cars, a lot of them supercharged, who never noticed a slowdown.


So I can understand people's skepticism. I think everyone believes that you were told this information. People are going to question whether the information is valid or not.

"Information"... I had someone on the 800 number tell me that using Ludicrous mode even once voids your warranty. It's not easy to get "information" from Tesla.
 
Perhaps this explains the throttling at supercharges. Maybe some algorithm as to number of slow home AC charges vs. fast DC charges to prevent warranty claims on batteries?

In general, lithium ion batteries should be charged at a C-rate of 0.8 or less. I haven't done the calculations to determine what that rate is without looking up capacity/voltages of Tesla packs.

I'll make it easy for you. 0.8 C rate is 1.25 hours, by definition of C rate. Look it up, it's the charge rate where the full capacity of the battery would be depleted in 1 hour. So at 0.8 C rate you get 1.25 hours.

The fallacy is thinking all lithium batteries are the same. They aren't.


Lithium ion packs degrade with every discharge cycle. I would assume there is a software buffer to allow for planned degradation. You lose about 10% capacity with 500 discharge cycles. I haven't studied this recently, so take what I am telling you with a grain of salt.

There is a graph that Tesla published (Well, Musk tweeted I believe) that shows very little degradation of the batteries for 1000s of cycles. It's in a video on YouTube. I need to book mark that and better, get the author to send it to me. I can't seem to find it in a Google image search.


If the OP has had a lot of cycles on his battery, and is charging at high C-rates, he will need a new pack soon.

Please don't say things you can't substantiate. Tesla batteries are not the same as every other battery.


IMO it is fraudulent for Tesla to use software to limit car performance or charging to save on warranty claims. They need to either establish policies at the sale of the car, or "suck it up" and pay for replacement parts on users that need it.

Given they are struggling to stay alive that ain't gonna happen.
 
“After further reviewing your concern of reduced supercharging rate we
have determined the cause to be due to the high amount of overall supercharging over the
life of the pack. The health of the pack is still as expected however to maintain this
health the rate of supercharging is slightly reduced as you have experienced. This is
also outlined in the on board owners manual. You also had questioned about the total
amount of energy the pack has charged and discharged. Keep in mind that the amount of
energy removed from the pack is not entirely used to drive the wheels. This energy is
used to heat and cool the cabin, power the vehicles low voltage electrical system, and
maintain the vehicle and the background functions like sentry mode when stationary. These
values as follows are as of today.

kWh Charge Counter: 18681.9 kWh
kWh Discharge Counter: 16952.7 kWh
AC Charge Counter: 2922.3 kWh
DC Charge Counter: 11755.1 kWh”

For the first full year of ownership, I had no access to home charging, but Supercharged approximately twice weekly not exceeding 90%. When I inquired during the purchase of my vehicle about this obstacle, I was plainly informed of two pieces of information...

1. Since I live so close, and lifetime Supercharging is included, I was advised to feel free to use as much as is necessary until home charging is established.

2. The Supercharger itself will “balance and protect” the pack from damage and the taper is designed to ensure the longest possible battery life. “It is literally a non-issue”.

Since I have a friend and family member with older 85 packs, performance and standard with almost 100K miles and they seemed to be just fine with regular even heavier Supercharging use, at my approximate 17K per year, it seemed to be a non-issue. I have since established home charging and only Supercharge for daily trip convenience or road trip necessity.

Well fast forward to approximately the 30K mile mark and I notice a max charge speed of 80kW down from the highest I have ever seen on the 350V pack of about 96kW. Other packs had then subsequently been increased to anywhere from 110-130kW and mine was permanently throttled at 80kW maximum.

I inquired and it was not until I was very vocal and adamant that there was a marked change in charging performance that they finally consulted someone in main engineering. The bad news above was returned shortly thereafter. Not until after three or four vocal complaints and a visit did they dive deeper; even local service was surprised and spend the better part of three months trying to convince me it was a normal combination of varying Supercharger performance, shared circuits, cold battery, hot Supercharger handles, lack of ideal temperatures...

The reality is, Tesla goofed on the 75/90 chemistry and are not taking ownership for the failure, but rather intends on reducing my ownership satisfaction to prevent increased warranty repair costs. It is interesting to meet other owners at the Supercharger with different battery variants and even triple the mileage and DC fast charging sessions, who say it performs same as the day they purchased it.

This adds considerable charging time to the 350V pack variants on trips of more than 300 miles and leaves a pretty bitter taste in my mouth especially since I have worked so hard to care for the pack by avoiding deep discharges and above 90% charging and never parking it full ect.

I make decisions with my wallet and I cannot further support a company with such terrible customer service, internal communication, lack of corporate responsibility and such a questionable people culture. I love my Model S despite its growing limitations and nerfs, and will keep it as long as it meets my needs, but I will not purchase another vehicle from the company and will carefully warn others who inquire of the risk involved.

I don’t expect everyone to agree of feel similar, but because you are not impacted, or not yet, does not mean this is not a real and growing concern as these vehicles age.

 
“After further reviewing your concern of reduced supercharging rate we
have determined the cause to be due to the high amount of overall supercharging over the
life of the pack. The health of the pack is still as expected however to maintain this
health the rate of supercharging is slightly reduced as you have experienced. This is
also outlined in the on board owners manual. You also had questioned about the total
amount of energy the pack has charged and discharged. Keep in mind that the amount of
energy removed from the pack is not entirely used to drive the wheels. This energy is
used to heat and cool the cabin, power the vehicles low voltage electrical system, and
maintain the vehicle and the background functions like sentry mode when stationary. These
values as follows are as of today.

kWh Charge Counter: 18681.9 kWh
kWh Discharge Counter: 16952.7 kWh
AC Charge Counter: 2922.3 kWh
DC Charge Counter: 11755.1 kWh”

For the first full year of ownership, I had no access to home charging, but Supercharged approximately twice weekly not exceeding 90%. When I inquired during the purchase of my vehicle about this obstacle, I was plainly informed of two pieces of information...

1. Since I live so close, and lifetime Supercharging is included, I was advised to feel free to use as much as is necessary until home charging is established.

2. The Supercharger itself will “balance and protect” the pack from damage and the taper is designed to ensure the longest possible battery life. “It is literally a non-issue”.

Since I have a friend and family member with older 85 packs, performance and standard with almost 100K miles and they seemed to be just fine with regular even heavier Supercharging use, at my approximate 17K per year, it seemed to be a non-issue. I have since established home charging and only Supercharge for daily trip convenience or road trip necessity.

Well fast forward to approximately the 30K mile mark and I notice a max charge speed of 80kW down from the highest I have ever seen on the 350V pack of about 96kW. Other packs had then subsequently been increased to anywhere from 110-130kW and mine was permanently throttled at 80kW maximum.

I inquired and it was not until I was very vocal and adamant that there was a marked change in charging performance that they finally consulted someone in main engineering. The bad news above was returned shortly thereafter. Not until after three or four vocal complaints and a visit did they dive deeper; even local service was surprised and spend the better part of three months trying to convince me it was a normal combination of varying Supercharger performance, shared circuits, cold battery, hot Supercharger handles, lack of ideal temperatures...

The reality is, Tesla goofed on the 75/90 chemistry and are not taking ownership for the failure, but rather intends on reducing my ownership satisfaction to prevent increased warranty repair costs. It is interesting to meet other owners at the Supercharger with different battery variants and even triple the mileage and DC fast charging sessions, who say it performs same as the day they purchased it.

This adds considerable charging time to the 350V pack variants on trips of more than 300 miles and leaves a pretty bitter taste in my mouth especially since I have worked so hard to care for the pack by avoiding deep discharges and above 90% charging and never parking it full ect.

I make decisions with my wallet and I cannot further support a company with such terrible customer service, internal communication, lack of corporate responsibility and such a questionable people culture. I love my Model S despite its growing limitations and nerfs, and will keep it as long as it meets my needs, but I will not purchase another vehicle from the company and will carefully warn others who inquire of the risk involved.

I don’t expect everyone to agree of feel similar, but because you are not impacted, or not yet, does not mean this is not a real and growing concern as these vehicles age.

I completely agree with you but I think part of the reason for tesla not addressing in my opinion is partly to get people to buy new cars and continue to pump the sales numbers. Once tesla becomes sustainable, I think they will probably replace the pack for most people with throttle issues and are complaining. I'm going to continue to drive and hope tesla reaches that point before my warranty ends in 2024.
 
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Reactions: robby
I think this is a YMMV issue.
A friend has a 75 with 80k miles and decent supercharger use. Still gets over 100kw. (Indiana)
My 70D with same mileage and less supercharger use - 100kw still.(North Carolina)
(Both of us have about 7% degradation)
There is a lot of learning here - for Tesla and for battery chemistry. This isn't Tesla's fault in my opinion. This is just what happens when you are doing something no one has done before.
I do think the 75 and 90s have inferior chemisty. Tesla figured it out fairly quickly it seems and changed it.
In the end, the battery life and charging pattern is reasonable. But no one should have told you that supercharging is fine to do all the time - that was a mistake.
Honestly - Tesla tries to take the simple route - "don't worry about it" because that is what the average consumer can handle.
Go back to battery basics and ignore what Tesla says. Fast charging is rough on batteries. High temps are rough on batteries. Keep battery near 50% for the majority of its life - charging higher (at moderate speed) before you drive.
All these things more important if you want to keep your car for many years and you live in a warmer area.
Yes - Tesla's BMS is good but physics are physics in the end. I was quite nervous about getting a 60 back in 2015 because of degradation and a 2nd home 150 miles away (In laws about the same opposite direction). The 70 (and then the D) gave me comfort for longevity and winter. Since that time, superchargers have been installed on both routes. And the wife got a LR3. But the 70D does fine at 80 mph in the winter with no supercharging. And looks like I may need to slow down in winter (or bathroom break at charger) in 5 years. Not bad really. Of course the 3 for longer trips.
 
Bigger batteries charge faster than smaller batteries of the same type (structure and chemistry). Tesla batteries seem to be made of multiple strings of batteries wired in parallel. The strings consist of batteries wired in series to produce 400 volts. Each string can absorb a maximum amount of current when new. As the batteries get older and experience more charge/discharge cycles the ability of the string to accept charge current and deliver discharge current declines. Tesla says the batteries will maintain 70% or more capacity after 8 years.

When capacity goes away it reduces the maximum charge and discharge current. Charging current times voltage equals the power that the battery can receive. Reduced Supercharging power levels is a direct consequence of reduced battery capacity. So, if a new battery could accept 120 kW charging then an 8 year old battery should be expected to accept 70% of that rate which is 84 kW. Attempting to charge at higher rates will result in energy being converted to heat rather than being stored in the desired chemical reaction. Placing a limit on charge rates seems to be the right course of action because it protects the battery and reduces the potential for overheating. The battery should last longer if the charge rate matches the capability of the battery.

I have a 2016 early facelift 75D (delivered as 70D.) When new, I got ~ 212mi rated range at 90% SOC. I could SC routinely at 92kw, best was 96kW. Today, at 50kmi traveled (So. California temperatures), I still get ~212 range at 90%, but I cannot exceed 81kw at a SC, even the new 250kW chargers. I charge almost exclusively at SC's, almost always to 90%. Tesla may be protecting my battery, but there is negligible apparent capacity degradation to point to.
 
I have a 2016 early facelift 75D (delivered as 70D.) When new, I got ~ 212mi rated range at 90% SOC. I could SC routinely at 92kw, best was 96kW. Today, at 50kmi traveled (So. California temperatures), I still get ~212 range at 90%, but I cannot exceed 81kw at a SC, even the new 250kW chargers. I charge almost exclusively at SC's, almost always to 90%. Tesla may be protecting my battery, but there is negligible apparent capacity degradation to point to.


That is correct. Your pack is now software restricted at Superchargers. See the linked video above, many of us experience the same with these packs and more will as well as the vehicles age. This specific charging speed nerf primarily affects 75/90 packs.
 

brianman

Burrito Founder
Nov 10, 2011
17,618
3,224
kWh Charge Counter: 18681.9 kWh
kWh Discharge Counter: 16952.7 kWh
AC Charge Counter: 2922.3 kWh
DC Charge Counter: 11755.1 kWh
Thanks for sharing! Since you probably can't edit your post by now, can you update your signature to describe your vehicle's configuration (and age)?

I'm confused so I'm probably missing something(s).

Observation 1:
Charging Sum = AC+DC = 2922.3 + 11755.1 = 14677.4
Charge Counter = 18681.9
18681.9 - 14677.4 = 4004.5 kWh …. from regen?

Observation 2:
Charge - Discharge = 18681.9 - 16952.7 = 1729.2
Even if your battery is currently full.... your battery capacity is 1729.2 kWh?
 
Thanks for sharing! Since you probably can't edit your post by now, can you update your signature to describe your vehicle's configuration (and age)?

I'm confused so I'm probably missing something(s).

Observation 1:
Charging Sum = AC+DC = 2922.3 + 11755.1 = 14677.4
Charge Counter = 18681.9
18681.9 - 14677.4 = 4004.5 kWh …. from regen?

Observation 2:
Charge - Discharge = 18681.9 - 16952.7 = 1729.2
Even if your battery is currently full.... your battery capacity is 1729.2 kWh?

Perhaps observation 2 is answered with system losses. Heating and such. 10% loss is pretty good I think. (if I got my signs right : )
 
Thanks for sharing! Since you probably can't edit your post by now, can you update your signature to describe your vehicle's configuration (and age)?

I'm confused so I'm probably missing something(s).

Observation 1:
Charging Sum = AC+DC = 2922.3 + 11755.1 = 14677.4
Charge Counter = 18681.9
18681.9 - 14677.4 = 4004.5 kWh …. from regen?

Observation 2:
Charge - Discharge = 18681.9 - 16952.7 = 1729.2
Even if your battery is currently full.... your battery capacity is 1729.2 kWh?

17’ S75D 40K miles. I am not even going to attempt to decipher those numbers above.

They came directly in writing from service. I don’t know how they relate to the total pack capacity.
 
I am not very informed, but I don't think it is in ALL older cars, just many or maybe most. eg had a loaner last week, 2014 S85 ... forget the details but I noted that its 80% was > 200 miles and it charged at a Supercharger >90 kW (was around 30% SOC). Only had ~36K miles and clearly was loved by its former owner. (BTW it was named Gandalf the Grey if anyone chooses to claim it).

90s clearly more likely ...
 

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