Pack Performance and Launch Mode Limits

[TSLA Pilot]

Tesla continues to amaze me.

They act in an Inception fashion whereby they provide a smidge of info or data and allow their customers to build a wold around one data point using their imagination.

I try to look at these things from a Tesla is smart perspective, add logical conclusions and try not to get sidelined or sidetracked with detail goose chases whose ultimate answers maybe out of reach.

The 69x hp at launch is an example. I do not care what the exact number is nor do I care if the original words can be twisted to be something else by a technical blog post using big words. What I did was work from previous work by other members to record chassis bus resident data. This tells me exactly how much Hp the system can produce and tells me Tesla knows this intimately. That is really all I need to know.

This power reduction is similar. I take my background in combination with others work on this form and conclude that battery concerns have Tesla dialing back 1600ish amps to 1500ish amps based on integrated use. The number of launches, mode, traction, etc makes for interesting conversation but only discovery or de compiling the BMS code is going to give answers. I'm not filing suit and I have yet to get a copy of the suspect firmware so I'm not concerned about these details.

My take away once again is that Tesla knows exactly what they are doing when they impose their will on their customers. These people grew up in an environment where customers can be dealt with with complete disregard. If one gets pissed, there is another to fill their place. This may or may not continue; I do not know as my businesses have never had that luxury. Customers have always been our most valuable asset and our best salespeople. Lasting or not, why take the chance?

Lastly, I find it a mixture of humorous and annoying (but mostly pathetic) when someone without skin in the game spends so much time writing lengthily posts about what those who do should do.

All excellent points.

We go into a new work week tomorrow and let's hope that Elon's direct reports have spent the last few days coming up with "The Plan" to make all P90D owners whole. I remain optimistic that, unlike VW's Dieselgate scandal, the upper echelons at Tesla had no idea that a counter was being added that would permanently degrade performance . . . and that now that they know they will take steps to undo the damage to customer trust and goodwill.

My hope would be enhanced trade-in value to get us out of the "cheater" P90D's as then Tesla can take the trade ins, strip the Ludicrous bar off the decklid, and sell them as CPO's (or put them in the Service Loaner fleet). Sounds like a win-win, no?

However, the earlier post where someone pasted the new language (re: they retain the ability to degrade performance on the P100D!) makes we wonder exactly what the true story is because, frankly, I don't think I'll be ponying up big money for a P100D knowing that they can do this again . . . .

 

[Garlan Garner]

So if the P90D didn't meet the 10.9 time with LaunchMode intact....how is there an expectation that it would meet it with LaunchMode limited?
What is the limited LaunchMode time?
Anyone here know?

I hope this thread isn't dedicated to a .3 reduction in a LaunchMode quarter mile time - which could happen if the wind blows the wrong way...or from cold tires or something.

 

[vgrinshpun]

My guess is that the counter doesn't know anything about launch mode, it just increments the counter anytime x Amps are drawn for more than y continuous seconds. (With x probably being ~1,600, and y being unknown at this time.) I'm guess the specific details listed earlier are the estimated conditions that allow you to hit the x Amps for y seconds.

Tesla stated that counter is related to the launch mode, and as I mentioned before, it makes sense technically. While the counter according to @Ingineer "is not related to thermals", meaning that it is not incremented based on thermals, it most definitely is based on prevention of certain level of thermal loading, even though it might be incremented based on the parameter which is related to thermal loading, but indirectly.

When car is not in the "launch mode", flooring it from standstill until the end of 1/4 mile mile takes about 11 seconds during which car is drawing 1600A. Putting car in launch mode ads up to 4 seconds to this time, resulting in proportionately higher temperature in the battery pack components, up to 36.4% higher (4/11=0.364). Based on Tesla statement about launch mode, it appears that additional time when current is drawn at a maximum of ~1600A causes temperature to exceed the limit above which lifetime exposure leads to derating of a certain component(s), hence limitation on power output in the "launch mode".

From the Manual:

3. While still pressing the brake with your left foot, fully press the accelerator pedal with your right foot, then release the accelerator pedal. The instrument panel displays a message indicating that Launch Mode is enabled.
4. Within eight seconds, fully press the accelerator pedal a second time to preload motor torque, then within four seconds, release the brake.

This, i.e. limitation imposed on higher temperature, by the way, is typical for sizing of many electrical materials and equipment (disclaimer - information below is based on my professional experience). Cables, for example, have normal and emergency temperature rating, based on insulation used. Based on normal temperature rating cables are expected to have useful life of 20 to 30 years. Cables are allowed to be loaded up to the emergency temperature rating for a certain limited amount of time and still have normal life expectancy. If the duration of loading that corresponds to emergency temperature exceeds specified limits, life expectancy is reduced. Here is example from IEEE standard 242-2001 (Para. 9.5.2.4, p. 313) for EPR and XLP cables that have normal temperature rating of 90˚C and emergency temperature rating of 130˚C:

"For example, EPR and XLP cables have emergency ratings of 130 ˚C, based on maximum time per overload of 36 h, three such periods per year maximum, and an average of one such period per year over the life of the cable."

 

[dhanson865]

Personally I don't think having skin in the game is necessary to have useful viewpoints or valid opinions on some matter. Sometimes I think opinions are overly subjective/based on subjective experiences. So, @Garlan Garner - go ahead and continue IMO. All views are IMO valuable.

Personally I find the quantity of his posts on this topic more a problem than the content of the posts. He's taken over / corrupted the flow of the messages in this topic. The signal to noise ratio inverted from one day to the next when he turned on the high flow posting mode.

 

[Garlan Garner]

Tesla stated that counter is related to the launch mode, and as I mentioned before, it makes sense technically. While the counter according to @Ingineer "is not related to thermals", meaning that it is not incremented based on thermals, it most definitely is based on prevention of certain level of thermal loading, even though it might be incremented based on the parameter which is related to thermal loading, but indirectly.

When car is not in the "launch mode", flooring it from standstill until the end of 1/4 mile mile takes about 11 seconds during which car is drawing 1600A. Putting car in launch mode ads up to 4 seconds to this time, resulting in proportionately higher temperature in the battery pack components, up to 36.4% higher (4/11=0.364). Based on Tesla statement about launch mode, it appears that additional time when current is draw at maximum of ~1600A causes temperature to exceed the limit above which lifetime exposure leads to derating of a certain component(s), hence limitation on power output in the "launch mode".

From the Manual:

3. While still pressing the brake with your left foot, fully press the accelerator pedal with your right foot, then release the accelerator pedal. The instrument panel displays a message indicating that Launch Mode is enabled.
4. Within eight seconds, fully press the accelerator pedal a second time to preload motor torque, then within four seconds, release the brake.

This, i.e. limitation imposed on higher temperature, by the way, is typical for sizing of many electrical materials and equipment (disclaimer - information below is based on my professional experience). Cables, for example, have normal and emergency temperature rating, based on insulation used. Based on normal temperature rating cables are expected to have useful life of 20 to 30 years. Cables are allowed to be loaded up to the emergency temperature rating for a certain limited amount of time and still have normal life expectancy. If the duration of loading that corresponds to emergency temperature exceeds specified limits, life expectancy is reduced. Here is example from IEEE standard 242-2001 (Para. 9.5.2.4, p. 313) for EPR and XLP cables that have normal temperature rating of 90˚C and emergency temperature rating of 130˚C:

"For example, EPR and XLP cables have emergency ratings of 130 ˚C, based on maximum time per overload of 36 h, three such periods per year maximum, and an average of one such period per year over the life of the cable."

From the Manual:

3. While still pressing the brake with your left foot, fully press the accelerator pedal with your right foot, then release the accelerator pedal. The instrument panel displays a message indicating that Launch Mode is enabled.
4. Within eight seconds, fully press the accelerator pedal a second time to preload motor torque, then within four seconds, release the brake.

So if the car only achieves the 1/4 mile in 15 seconds with a non-limited LaunchMode, then what's the limitation counter dropping it down to?

 

[St Charles]

Wow, I wasn't aware of that, cool. Well you know who would say a 10.99 is a 10.9 which is probably right so that's cool. That means you still have a chance.

This is really a matter of accuracy vs precision. The number of zeroes after the decimal point is a matter of precision and it's no more or less accurate to add/drop decimal places. In that vein a 10.99 is the same as a 10.9.

a 10.9 is accurate.
a 10.99 is accurate and more precise.
rounding a 10.99 to 11.00 is not accurate.

Hopefully this is provides some clarity to the racing world.

 

[SDRick]

Tesla stated that counter is related to the launch mode, and as I mentioned before, it makes sense technically. While the counter according to @Ingineer "is not related to thermals", meaning that it is not incremented based on thermals, it most definitely is based on prevention of certain level of thermal loading, even though it might be incremented based on the parameter which is related to thermal loading, but indirectly.

When car is not in the "launch mode", flooring it from standstill until the end of 1/4 mile mile takes about 11 seconds during which car is drawing 1600A. Putting car in launch mode ads up to 4 seconds to this time, resulting in proportionately higher temperature in the battery pack components, up to 36.4% higher (4/11=0.364). Based on Tesla statement about launch mode, it appears that additional time when current is drawn at a maximum of ~1600A causes temperature to exceed the limit above which lifetime exposure leads to derating of a certain component(s), hence limitation on power output in the "launch mode".

From the Manual:

3. While still pressing the brake with your left foot, fully press the accelerator pedal with your right foot, then release the accelerator pedal. The instrument panel displays a message indicating that Launch Mode is enabled.
4. Within eight seconds, fully press the accelerator pedal a second time to preload motor torque, then within four seconds, release the brake.

This, i.e. limitation imposed on higher temperature, by the way, is typical for sizing of many electrical materials and equipment (disclaimer - information below is based on my professional experience). Cables, for example, have normal and emergency temperature rating, based on insulation used. Based on normal temperature rating cables are expected to have useful life of 20 to 30 years. Cables are allowed to be loaded up to the emergency temperature rating for a certain limited amount of time and still have normal life expectancy. If the duration of loading that corresponds to emergency temperature exceeds specified limits, life expectancy is reduced. Here is example from IEEE standard 242-2001 (Para. 9.5.2.4, p. 313) for EPR and XLP cables that have normal temperature rating of 90˚C and emergency temperature rating of 130˚C:

"For example, EPR and XLP cables have emergency ratings of 130 ˚C, based on maximum time per overload of 36 h, three such periods per year maximum, and an average of one such period per year over the life of the cable."

Hopefully it is only the launch mode scenario that causes the problem. Intuitively, this makes sense. Providing power to an electric motor, even for a short time (no pun intended), and not letting it turn is never good for longevity of the components.

 

[vgrinshpun]

So if the car only achieves the 1/4 mile in 15 seconds with a non-limited LaunchMode, then what's the limitation counter dropping it down to?

If it takes 15 seconds to do 1/4 mile, the power output is limited by traction, which means that car is drawing less than 1600 amps --> the critical (trigger) temperature is not reached, i.e. counter is not triggerred.

 

[rowdy]

I'd be amazed if it didn't affect non launch modes too...

Otherwise you can roll at 10mph and then floor it pulling 500kW til hitting top speed and do this an unlimited number of times...
Whereas launching from 0mph and pulling 500kW is going to cause critical damage after a mere 25 times?.

What's the difference to the battery?

I think MP3mike had it right. counter will be going up when it's over X amps for Y time.

 

[vgrinshpun]

Hopefully it is only the launch mode scenario that causes the problem. Intuitively, this makes sense. Providing power to an electric motor, even for a short time (no pun intended), and not letting it turn is never good for longevity of the components.

Just to make it clear, I, as @MP3Mike and @lolachampcar, do not believe that trigger of the counter is related to the loading of drive unit, it is IMO is related to some component(s) in the battery pack reaching certain critical temperature. In addition to various indirect evidence mentioned by MP3Mike and Lolachampcar, there is direct [proof of this: rating of the drive units according to ECE R85 is based on 30 minutes, so there is no way the counter is triggered due to drive units operating at their maximum rating for seconds.

 

[vgrinshpun]

I'd be amazed if it didn't affect non launch modes too...

Otherwise you can roll at 10mph and then floor it pulling 500kW til hitting top speed and do this an unlimited number of times...
Whereas launching from 0mph and pulling 500kW is going to cause critical damage after a mere 25 times?.

What's the difference to the battery?

I think MP3mike had it right. counter will be going up when it's over X amps for Y time.

The power drops off the maximum level well before the car reaches maximum speed, so gunning it from 10mph to 155mph will not produce heat load equivalent to "launch mode", i.e. max power for up to 15 seconds.

 

[rowdy]

The power drops off the maximum level well before the car reaches maximum speed, so gunning it from 10mph to 155mph will not produce heat load equivalent to "launch mode", i.e. max power for up to 15 seconds.

So 10->155 for 14.5 seconds can be done unlimited
But 0->155 for 15 seconds is going to cause massive damage?

I guess time will tell.....

 

[St Charles]

It's been my experience that LM loads about 35kW of power into the system. I got this figure though datalogging. You can see the difference between the two attachments here. One was a pass where I used Launch Mode, another where I floored the pedal.

You'll also note that My P90DL only holds max-ish power until about 90MPH at which point it begins to drop off significantly.

 

[vgrinshpun]

So 10->155 for 14.5 seconds can be done unlimited
But 0->155 for 15 seconds is going to cause massive damage?

I guess time will tell.....

It seems that you are missing the point - the car does not draw maximum power at higher speeds. So acceleration 1/4 mile with "launch mode" represents worst case scenario.

Do not put words in my mouse. I did not say anything about massive damage. The discussion was about reaching certain temperature that can impact life expectancy.

 

[rowdy]

Thanks St Charles for the data.

Apologies to vgrinshpun - I'm not trying to put words into your mouth... .Just trying to point out that the load on the battery is fairly similar for a roll (10mph) vs a launch (0mph).

If you look at st charles graphs, both will be pulling peak power for around 5 seconds.

If the battery is only outputting 35kw pre-launch I really don't think this can be stressing the battery to the point that it impacts life expectancy..

 

[vgrinshpun]

It's been my experience that LM loads about 35kW of power into the system. I got this figure though datalogging. You can see the difference between the two attachments here. One was a pass where I used Launch Mode, another where I floored the pedal.

You'll also note that My P90DL only holds max-ish power until about 90MPH at which point it begins to drop off significantly.

Thanks for the curves. The comparison of heat load between the "launch mode" vs. no launch mode can be done by comparing areas under the red curves. The extra area for the "launch mode" is equivalent to the additional heat load experienced when car put in "launch mode".

 

[vgrinshpun]

Thanks St Charles for the data.

Apologies to vgrinshpun - I'm not trying to put words into your mouth... .Just trying to point out that the load on the battery is fairly similar for a roll (10mph) vs a launch (0mph).

If you look at st charles graphs, both will be pulling peak power for around 5 seconds.

If the battery is only outputting 35kw pre-launch I really don't think this can be stressing the battery to the point that it impacts life expectancy..

What I am saying is that it is NOT similar - because power starts to drop out at ~90mph. In order to do proper quantitative analysis one needs to look at power curves for these two cases and compare areas under the curves.

As far as power drawn during the "launch mode", the key is that this is heat load on top of the heat load associated with the launch. It is additive, proportionate to the additional area under the power curve.

 

[NSX1992]

Here is the deal..

This only impacts P90Ds. There is a lifetime counter on launches. However, to count as a launch a bunch of crieteria must be met:

1. Launch mode must be on
2. SOC must be >90%
3. Perfect traction must be maintained. Any amount of slip will cause power to be reduced and it won't count.

The limit is 25 for the rear drive unit. If this limit is hit, power is reduced slightly resulting is a difference of 0.05s 0-60.

Basically, unless you regularly take your car to the drag strip and can manage to maintain perfect traction while meeting all or the other conditions above, this is a non-issue.

I encourage everyone not to blow this out of proportion.

Some people have taken the 25 Launch Mode runs triggering the reduction in power as gospel but my guess is that andrewket was being sarcastic. Since I take my P85DL regularly to the track I can verify that it makes no difference if you have Launch Mode on or slip mode or just punch the pedal a small amount of slip does occur. If power is reduced during slip for a split second that will have minimal effect on the total amount of power the battery is subjected to. I don't think anyone knows the real number.

 

[NSX1992]

At this point then .... someone is going to have to take official sub times so to Tesla. Did Techguy take these measurements?

Since I am the one who encouraged Tech_Guy to take his Tesla to the track to get the magic 10.9 and found out from him that his power was reduced and therefore he would not take it to the track. So he does not have any before and after times for the 1/4 mile. But he clearly knows the exact reduction based on measurements of his battery power.

 

[NSX1992]

So if the P90D didn't meet the 10.9 time with LaunchMode intact....how is there an expectation that it would meet it with LaunchMode limited?
What is the limited LaunchMode time?
Anyone here know?

I hope this thread isn't dedicated to a .3 reduction in a LaunchMode quarter mile time - which could happen if the wind blows the wrong way...or from cold tires or something.

You are apparently new to the 10.9 problem with no P90DL V1 except for Motor Trend being able to meet it that has been discussed to death. Launch Mode has very little if any effect on times and I don't understand your question "What is the limited LaunchMode time?