Fast Charging Problem?

ajdelange

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A CT is going to require 400 - 500 Wh/mi. Tesla's biggest charger is 250 kW. That means charging rates of at best 500 - 625 miles per hour added at a SC (before taper cuts in) implying 24 - 30 minutes to replenish 250 miles. EA's biggest chargers are 350 kW meaning that were they compatible with the CT it could charge from them at 700 - 875 miles per hour implying 17 - 21 minutes to take on those 250 mi. The CT will not be compatible but the Rivian trucks, with comparable consumption are. They can take 300 kW from an EA charger meaning 600 - 750 miles per hour rate and 20 - 25 minutes to replenish 250 mi. Soon the Lucid will be along and with it's 800 V architecture and lower consumption (it's not a truck or SUV) will probably best any of those times by several minutes.

My first qestion is: Will this be seen as a competitive disadvantage by Tesla to the point that they will do something about it?

The second is: What will/can they do?

The obvious answer to the second question is to do what they do with the Semi i.e. let it plug into two SC terminals at once. That would allow 1400 - 1750 miles per hour added and 250 mile times of 8.5 - 10.5 minutes putting them way out in front of the others. Clearly there are some implications here so the third question becomes: Will Tesla do this?

Another approach is to do what Rivian does which is split the battery into two halves and connect them in series for charging and parallel for running the truck. This would allow Tesla to use the EA chargers if they added a CCS connector (which I wouldn't frown on) getting the CT into the 17 - 21 min range for 250 mi.
There are clearly implications here too (such as Rivian's patent on this technique).

??
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Crissa

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A CT is going to require 400 - 500 Wh/mi.
We don't know how much it will require. That's on the high end. We don't know if they'll do split charging like the Semi's currently use. We also don't know if they'll change any charging infrastructure.

So if you posit that energy consumption - twice that of current Teslas - then charging speeds (per mile) will be abysmal, at 8 miles a minute instead of the current 16.

It would mean for every hour you spend at highway speed you need to charge seven minutes.

That's not entirely terrible, but it's not great, either.

-Crissa
 

Owner13669

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For one, I assume the cybertruck batteries will charge faster because of improved cooling and less resistance, meaning they will not be forced to taper down charging as much as current vehicles. And Elon did say there was more to say about charging.
 

Ehninger1212

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We don't know how much it will require. That's on the high end. We don't know if they'll do split charging like the Semi's currently use. We also don't know if they'll change any charging infrastructure.

So if you posit that energy consumption - twice that of current Teslas - then charging speeds (per mile) will be abysmal, at 8 miles a minute instead of the current 16.

It would mean for every hour you spend at highway speed you need to charge seven minutes.

That's not entirely terrible, but it's not great, either.

-Crissa
Only 7 Minutes for every hour?? I never put it into this perspective, usually after two hours of driving to pull over for 15 or so minutes anyways, whether I need gas or not.
 
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ajdelange

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For one, I assume the cybertruck batteries will charge faster because of improved cooling and less resistance, meaning they will not be forced to taper down charging as much as current vehicles.
I kept taper out of it because I wanted to keep it simple but taper really doesn't have that much effect. The scenario I chose has the driver replacing half the battery presumably after every 4 or so hours of driving. If he manages his charging well that will be between 10% and 60% as opposed to 45% to 95%.
ChargeTaper.jpg

As the chart shows it would take 21.6 minutes to do this charge with no taper, 23.1 minutes with taper starting at 20% SoC and and 27.3 minutes were the taper to start at 20% SoC. Tapers are assumed to be linear down to 10% of the charger's capacity at 100% SoC. OTOH if you are talking about a fuller charge, taper has a very great effect and it is clear that a manufacturer who doesn't start taper until 90% can earn big bragging rights by talking about the fact that he can charge to 90% in 35 minutes as opposed to his competition's 55 - 60 minutes time for the same thing. There are many games a manufacturer can play simply by changing the "size" of his battery by refining where 0% and 100% SoC are and there are those who accuse Tesla of "cheating" in this regard. But as I said, I wanted to keep it down to the relatively simple implications of the fact that Tesla's biggest charger is 250 kW while its competitors have access to 350 kW. And my basic questions remain "Will Tesla grant access to the larger chargers already out there?" (have to rewicker the battery and add CCS) and "Will Tesla build a 500 kW charger?" with the 500 kW charger being 2 V3's in 1 cabinet with two hoses (have to add a second charge port).

And Elon did say there was more to say about charging.
I am anxiously awaiting any further revelations. I just don't see how Musk could tolerate being in second place on charging.
 
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ajdelange

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... usually after two hours of driving to pull over for 15 or so minutes anyways, whether I need gas or not.
The car's ranges have improved (the X just got another 20 miles) and the driver degraded to the point that of the two B's Bladder now usually comes before Battery.
 

Owner13669

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I kept taper out of it because I wanted to keep it simple but taper really doesn't have that much effect. The scenario I chose has the driver replacing half the battery presumably after every 4 or so hours of driving. If he manages his charging well that will be between 10% and 60% as opposed to 45% to 95%.
ChargeTaper.jpg

As the chart shows it would take 21.6 minutes to do this charge with no taper, 23.1 minutes with taper starting at 20% SoC and and 27.3 minutes were the taper to start at 20% SoC. Tapers are assumed to be linear down to 10% of the charger's capacity at 100% SoC. OTOH if you are talking about a fuller charge, taper has a very great effect and it is clear that a manufacturer who doesn't start taper until 90% can earn big bragging rights by talking about the fact that he can charge to 90% in 35 minutes as opposed to his competition's 55 - 60 minutes time for the same thing. There are many games a manufacturer can play simply by changing the "size" of his battery by refining where 0% and 100% SoC are and there are those who accuse Tesla of "cheating" in this regard. But as I said, I wanted to keep it down to the relatively simple implications of the fact that Tesla's biggest charger is 250 kW while its competitors have access to 350 kW. And my basic questions remain "Will Tesla grant access to the larger chargers already out there?" (have to rewicker the battery and add CCS) and "Will Tesla build a 500 kW charger?" with the 500 kW charger being 2 V3's in 1 cabinet with two hoses (have to add a second charge port).

I am anxiously awaiting any further revelations. I just don't see how Musk could tolerate being in second place on charging.
If tapers happen because of heat, lower resistance and better cooling might reduce the need for them. But I’m not an engineer, obviously.
 

Owner13669

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If tapers happen because of heat, lower resistance and better cooling might reduce the need for them. But I’m not an engineer, obviously.
And to be clear, I drive a bolt, that has a pretty severe taper around 50%. And more later as well.
 
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ajdelange

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There is a lot more to it than just heat depending on the battery chemistry. SEI layer interaction, dendrite formation, physical stesses.... I am not qualified to discuss any of them beyond making the very broad statement that in general fast charging of lithium cells at high SoC is stressful on them and to be avoided to the extent possible. Tesla tells you in its manuals to avoid Super Chargers to the extent possible, will warn you if you charge over 90% in a short time span and will even limit the amount of charge the car can take if you continue to do this, Beyond that I believe one of the reasons for limiting on board charging to 48 A (older S and X vehicles took 72 A and some 80) is at least partially motivated by this. Gentle charging prolongs battery life.ww

It's a complicated subject for sure.
 

Ehninger1212

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There is a lot more to it than just heat depending on the battery chemistry. SEI layer interaction, dendrite formation, physical stesses.... I am not qualified to discuss any of them beyond making the very broad statement that in general fast charging of lithium cells at high SoC is stressful on them and to be avoided to the extent possible. Tesla tells you in its manuals to avoid Super Chargers to the extent possible, will warn you if you charge over 90% in a short time span and will even limit the amount of charge the car can take if you continue to do this, Beyond that I believe one of the reasons for limiting on board charging to 48 A (older S and X vehicles took 72 A and some 80) is at least partially motivated by this. Gentle charging prolongs battery life.ww

It's a complicated subject for sure.
Yes, clearly complicated. I tend to just take it for what it is and not dwell on it to much lol. It seems Tesla is even still trying to get it all figured out, I imagine even the new cells will have a learning curve as well. But i'm sure it will be forward progress.
 
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ajdelange

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This brings up an important aspect of all this. Tesla has billions of miles worth of battery performance data under real driving conditions to guide it in its battery evolution programs.
 

Crissa

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Supercharging has only a minimal effect on battery life - it's the ambient temperature that it's charging at that makes a bigger effect. (Sorry, his cite is a 50x error and his clickbait title is insulting and contradicted by his article and conclusions)

Of course, when you drive on the highway, you're heating up your battery excessively. So if you need to use a Supercharger but not travel, don't add in more pre-heating than the car needs (telling your Tesla you're headed to a Supercharger will make it pre-heat itself).

This video is great, but he didn't cover State-of-Charge and storage, which exacerbates aging if away from that 60% happy medium.

-Crissa
 

pablopelos

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A CT is going to require 400 - 500 Wh/mi. Tesla's biggest charger is 250 kW. That means charging rates of at best 500 - 625 miles per hour added at a SC (before taper cuts in) implying 24 - 30 minutes to replenish 250 miles. EA's biggest chargers are 350 kW meaning that were they compatible with the CT it could charge from them at 700 - 875 miles per hour implying 17 - 21 minutes to take on those 250 mi. The CT will not be compatible but the Rivian trucks, with comparable consumption are. They can take 300 kW from an EA charger meaning 600 - 750 miles per hour rate and 20 - 25 minutes to replenish 250 mi. Soon the Lucid will be along and with it's 800 V architecture and lower consumption (it's not a truck or SUV) will probably best any of those times by several minutes.

My first qestion is: Will this be seen as a competitive disadvantage by Tesla to the point that they will do something about it?

The second is: What will/can they do?

The obvious answer to the second question is to do what they do with the Semi i.e. let it plug into two SC terminals at once. That would allow 1400 - 1750 miles per hour added and 250 mile times of 8.5 - 10.5 minutes putting them way out in front of the others. Clearly there are some implications here so the third question becomes: Will Tesla do this?

Another approach is to do what Rivian does which is split the battery into two halves and connect them in series for charging and parallel for running the truck. This would allow Tesla to use the EA chargers if they added a CCS connector (which I wouldn't frown on) getting the CT into the 17 - 21 min range for 250 mi.
There are clearly implications here too (such as Rivian's patent on this technique).

??
From what I understand the new tabless batteries have faster charging time and can handle more current. I would think with these improvements we could see a charge rate of ~1000+ miles/hr.
 
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