GT Performance and Battery Discharge

Blitz118

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I'm wondering how repeatable is the performance of the GT. If you were to take to the track, can you run it back to back, and how much will the performance degrade? I've seen videos of the Porsche Taycan, and it can run back to back 0-60, and the power will not degrade. The Porsche is another price level, though, and it was built to perform that way. When I go to the NY auto show, I'm going to ask them about that. In the past, the people at the stands don't know much about the cars except the basic specs. They're just there to answer basic questions.

Another thing I'm curious about is how much does the battery discharges when it's off the charger parked.





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w3rkn

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I am curious why you think the performance will degrade. Only the battery charge will degrade, until you get to 10% and the car goes into some type of power saving mode.

Unless you plan on doing a 100 miles of tracking, I doubt you'll see any performance deg.
 

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The battery voltage will drop as it is being discharged. Simple explanation is as the battery chemistry changes do to discharging the effective internal resistance of the battery increases. So do to that there is less wattage available to the motor when the motor controller is delivering as much power as it can. This phenomena is observable on the Tesla's at the track and likely is observable and perhaps worse with the Ford's battery chemistry.

The Porsche is using a different battery chemistry but more importantly the pack is producing a much higher voltage, something like twice as high. I suspect they are able to regulate it better because they have much more head room with respect to the required motor voltage. This may be where all cars will be headed, 800V battery packs. For now it's cost and as usual you will pay more for the Porsche's performance.
 

ejss

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I think this GT will be fun to play with, but in 5 years or so, we will have a fun road course EV track vehicle. Also, that would give them data to analyze for developing a more track-oriented vehicle (GT350E perhaps? That would be my wish).
 

w3rkn

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The battery voltage will drop as it is being discharged. Simple explanation is as the battery chemistry changes do to discharging the effective internal resistance of the battery increases. So do to that there is less wattage available to the motor when the motor controller is delivering as much power as it can. This phenomena is observable on the Tesla's at the track and likely is observable and perhaps worse with the Ford's battery chemistry.

The Porsche is using a different battery chemistry but more importantly the pack is producing a much higher voltage, something like twice as high. I suspect they are able to regulate it better because they have much more head room with respect to the required motor voltage. This may be where all cars will be headed, 800V battery packs. For now it's cost and as usual you will pay more for the Porsche's performance.
I understand that, but you would have to be at a drag strip and do 20-25 launches, before you would reduce the battery any significant amount.

I follow Formula E and am aware of the analytics/nth degree in performance and efficiency, etc. I am talking about in reality and in everyday life, you don't much ever put 50 miles on the track at any event. That is a 1/3rd of a GT's range, but you don't do that all at once, it is throughout the day and can be charged between sessions, etc.


That said, I do understand the question... of how much can it do, before it degradation sets in... I suspect, that will be part of an EV's performance metric, or in testing/reviews.
 

Whatstreet

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I understand that, but you would have to be at a drag strip and do 20-25 launches, before you would reduce the battery any significant amount.

I follow Formula E and am aware of the analytics/nth degree in performance and efficiency, etc. I am talking about in reality and in everyday life, you don't much ever put 50 miles on the track at any event. That is a 1/3rd of a GT's range, but you don't do that all at once, it is throughout the day and can be charged between sessions, etc.


That said, I do understand the question... of how much can it do, before it degradation sets in... I suspect, that will be part of an EV's performance metric, or in testing/reviews.
For the Tesla, the track time will be slightly lower for each run. It draws a lot of power to hit 130 mph in a half mile. Twenty launches and the range may have dropped by one hundred miles. Charging between runs would eliminate any perceivable drop but most Tesla drivers do not have away to charge while at the track. There are some extreme enthusiasts that have more than one car and a big generator, but that's not most people.

As to degradation of the battery capacity rather than reducing the state of charge, the temperature of the battery is very important and it might be possible to over heat the battery of a road car that would reduce the battery life some.
 
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Popeye

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Since we are talking about battery. Does anyone know why Tesla is the only EV manufacturer that uses cylindrical cells while the rest use pouches? Cylindrical cells do have a higher capacity, if I am not mistaken, they also have a faster charging. I would imagine price is main motivator, but you can have a smaller battery pack to accommodate the same range, if not better. It is my understanding that the cylindrical cells degrade slower than the pouches.
 

Whatstreet

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Tesla manufactures their own batteries at their gigafactory location in Nevada. Their batteries are captive to Tesla. The news is saying that Tesla has new batteries that will last a million miles available soon.
 

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Ford has invested $500 mil into a solid state battery company, which promises to increase capacity and significantly reduce the risk of fire. But considering how long Tesla has been using cells vs pouches vs cells, I would have thought LG Chem who is supplying Ford, would have had those available to Ford.
 

Whatstreet

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I don't know why Ford chose pouch type cells over cylindrical cells. It is reported that the cylindrical cells have advantages over pouch cells. They are more robust, they dissipate heat better and can be produced faster in manufacturing.

The pouch cells take up less space so the pack can be smaller for a given capacity.

Tesla gets their cells from Panasonic and more recently LG for cars produced in China.

I think the anode chemistry is different on the Tesla batteries, but all of this will be rapidly changing. Probably cost will be a big issue on cell selection.

In the early specs on the Mach-e, acceleration time increased with battery pack capacity which is contrary to Tesla specs. I think I'll revisit that again and see if that's still the case in another month or so.
 

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So... a thing or two.

First, contrary to what we've been conditioned from Tesla to believe or hear, the cylindrical batteries are good for making custom batteries that fit any which way or shape... but as you can see here from a "source" who is an engineer at Ford, they went with the pouch design for a great pack of power b/c pouches are generally better... but cooling os whwre Tesla has an advantage... but it is readily known that Tesla Batteries in either the S/X and 3/Y do have superior cooling which does help with range and the batteries lasting between charges.

Also, it is shown here that the aerodynamics of the Tesla add an advantage as well, but then, that's why Tesla's designs can be a bit "bland (although I was on the list to buy a 3 or a Y before the Mach-E came out, because Tesla is the EV leader)", saying the "Jelly Bean" look is spot on and is not in anyway as cool and dynamic as the Mach-E.
Mustang owners and the design team are/were more than happy to sacrifice a bit on the vehicle's CD, for styling.
And another thing that this source mentioned and that Dave P. - Director of Icons at Ford said on Autoline After Hours Show on YouTube (I love that show and their in depth and thorough, honest take on cars... check them out.) that basically Tesla makes claims about ranges but often doesn't deliver in real world driving, where as when Ford says 300 miles, or 280 or 250 etc., they seem to believe that at a *MINIMUM* the range will be the advertised range but may actually be a bit better depending. So it will really be interesting to see if that pans out. Tesla is notorious for saying 300 or whatever, but people rarely see it... Ford seems to have a more solid take that their battery designs are solidly what they say they are, but may actually be sandbagging a bit so they may get a tad better... time will tell.

Finally, in many/any Tesla Drag race videos, it seems to me that even after 5 or so runs at max power Teslas begin losing peak power, which is completely understandable and should be expected even in the Mach-E... most of the time Tesla starts to limit the power after a few full-tilt runs to protect the batteries... so I am sure each manufacturer will do the same thing.

Autoline After Hours - Mach-E Discussion

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