PSCB Brakes

[Jhenson29]

Are you forgetting what you said? These forums man...it's really hard to not get salty.

You said, "on 90% regen braking is diminishing returns though, no?" referring to my post that claimed a 90% reduction in brake dust (Porsche claim). People make mistakes in their writing; however you seem to claim that regen would require less braking so less dust. That is not the case and certainly not practical.

The regen is NOT a replacement for brakes; not even close. Regen in the context of the Taycan barely offers a braking (aka slowing) function, therefore it does not reduce the need for brakes, therefore it does not reduce brake DUST.

The only cars that would offer less braking and therefore less dust, are cars with a one pedal driving option hence my earlier comments. Or of course, selecting options such as PSCBs or PCCBs.

Now I am rolling my eyes...seriously, as I am writing this, I am rolling my eyes.

Dude, you’re so far off here… I don’t have time to properly respond now. Maybe tomorrow. But I wanted to at least acknowledge your vast and extreme incorrectness.

Sponsored

 

[Jhenson29]

So I'm not sure what the argument you all are having is all about. Since 90% of the braking with a Taycan is from regenerative braking it kind of makes sense that there would be a large, maybe even 90% decrease in brake dust since, compared to an ICE car, the actual mechanical brakes are used 90% less. However, having PSCBs reduces this even more to an almost minuscule level.

I was saying that if 90% of braking is with regen, then the remaining dust for PSCB to reduce by 90% is relatively low in the first place, thus the diminishing returns.

Basically that @Skilly statement of a 90% reduction in brake dust doesn’t carry the same weight as it does on an ICE. But he doesn’t understand how regen works.

 

[Skilly]

Porsche engineers have said that as much as 90% of the Taycan's braking will, on average, be achieved through regenerative braking.

This may be where the confusion, and resulting 'friction' (see what I did there) is coming from. This is a very poorly worded account of what is going on.

It would be true to say that 90% of the regenerative capabilities would be achieved through braking. It would not be correct to say that 90% of the braking requirements for a Taycan would be achieved through the regenerative function itself.

The sentence you pulled suggests the later, but that isn't the case. I suspect that they meant the former, which (give or take) seems entirely possible.

Let's say this. Regen is primarily activated and optimized during braking; more braking equates to more regenerative function. That said, the practical braking function for a Taycan operates almost identically to a traditional 2 pedal car system. I say 'almost' in that there is a slight resistance to forward motion during regen functions without applying the brake pedal.

 

[Skilly]

Dude, you’re so far off here… I don’t have time to properly respond now. Maybe tomorrow. But I wanted to at least acknowledge your vast and extreme incorrectness.

says the guy who believes that brakes should be replaced because of time. OK

 

[Jhenson29]

says the guy who believes that brakes should be replaced because of time. OK

I believe what I said is that was my understanding of Porsche’s basis of recommendation.

 

[Skilly]

I believe what I said is that was my understanding of Porsche’s basis of recommendation.

take a breath and read post 48.

 

[gnop1950]

This may be where the confusion, and resulting 'friction' (see what I did there) is coming from. This is a very poorly worded account of what is going on.

It would be true to say that 90% of the regenerative capabilities would be achieved through braking. It would not be correct to say that 90% of the braking requirements for a Taycan would be achieved through the regenerative function itself.

The sentence you pulled suggests the later, but that isn't the case. I suspect that they meant the former, which (give or take) seems entirely possible.

Let's say this. Regen is primarily activated and optimized during braking; more braking equates to more regenerative function. That said, the practical braking function for a Taycan operates almost identically to a traditional 2 pedal car system. I say 'almost' in that there is a slight resistance to forward motion during regen functions without applying the brake pedal.

According to Porsche, it isn't slight resistance, but on average supplies up to 90% of the braking power. This is really no different than the one-pedal driving in a Tesla that I've been told can almost eliminate the use of the mechanical brake pedal. (Note: I detested the one-pedal driving on my only Tesla test drive.)

The difference in the Taycan is that the same regenerative braking power, actually more than is provided by a Tesla, is applied by using the brake pedal and not by simply lifting off of the go pedal.

Personally, I like it as it makes it feel much more like a traditional car. You can actually see how much regeneration is being used if you have the power meter up on your instrument cluster when you are braking.

P.S. You can turn on Regen so that it does provide some regen when you lift off of the go pedal, but it is a pretty small amount akin to engine braking. I don't bother as I like coasting much better now that I'm used to it.

 

[wurzitup]

This post is hilarious...... I'm getting a good laugh out of watching you guys. All in good fun.
I think you're both saying the same thing....... however-

90% of braking (most of the time) is delivered through the braking action of the motors........ HOWEVER-

when I fly down an off ramp at 105mph and slow to 45mph, MOST of the braking action (greater than 70%?) is being generated from the mechanical brakes- can we all agree on that?. Up to 270 kW is being generated by the motors, and the remaining 500kw is being generated by the mechanical rotors and pads. Which is where the PSCBs will excel. Not in their better braking force, but in their superior hardness and ability to not create brake dust as a cosmetic benefit. If you use your brakes fairly frequently in a high braking pressure use, I imagine you will see (like I do) less brake dust. When the Mission E are light colored as they are as are the calipers, having to wash brake dust less frequently and longer pad/rotor intervals may be a benefit as I calculated. Now I may in fact negate this benefit by repeated heavy use of them...... but they still look cool.
I'm sure Porsche would like the rotors changed at scheduled time intervals, but if they are inspected to be fine and within tolerances at 7 years, I certainly won't be replacing them.
Just my $0.02.

 

[Skilly]

OK so what you are saying is that while you are using the traditional 2 pedal function the motors are simulating brake bias and the brakes aren't actually being applied except to compensate in such a minor way? If that is the case, @Jhenson29 I owe you a huge apology for my saltiness and humbly agree that I was talking out of my a**.

Its genius and so traditional like that it never occured to me and I was too busy talking and not enough listening. It just doesn't feel like that at all...Is there a white paper or more detailed explanation on this? I equate this giant calipers and rotors to having a purpose - it never occured to me that they would only be there for 10% of the overall braking function. Now it seems like a great deal of overkill.

mind = blown.

 

[gnop1950]

This post is hilarious...... I'm getting a good laugh out of watching you guys. All in good fun.
I think you're both saying the same thing....... however-

90% of braking (most of the time) is delivered through the braking action of the motors........ HOWEVER-

when I fly down an off ramp at 105mph and slow to 45mph, MOST of the braking action (greater than 70%?) is being generated from the mechanical brakes- can we all agree on that?. Up to 270 kW is being generated by the motors, and the remaining 500kw is being generated by the mechanical rotors and pads. Which is where the PSCBs will excel. Not in their better braking force, but in their superior hardness and ability to not create brake dust as a cosmetic benefit. If you use your brakes fairly frequently in a high braking pressure use, I imagine you will see (like I do) less brake dust. When the Mission E are light colored as they are as are the calipers, having to wash brake dust less frequently and longer pad/rotor intervals may be a benefit as I calculated. Now I may in fact negate this benefit by repeated heavy use of them...... but they still look cool.
I'm sure Porsche would like the rotors changed at scheduled time intervals, but if they are inspected to be fine and within tolerances at 7 years, I certainly won't be replacing them.
Just my $0.02.

I think the initial disconnect had to do with at least one side not understanding how much braking power is provided by regen. When you do a hard break, panic stop, etc. the mechanical brakes are, of course, much more involved. The Porsche statement was 90% on average of the braking power comes from regen.

Now there are lots of other caveats. For example, I understand that the car will prefer the mechanical brakes for some period of time/distance when you first get the car to break in the mechanical brakes.

But this is a discussion about PSCBs and the brake dust reduction/performance/etc. One side of the argument that started all of this is that since braking on a Taycan will use the mechanical brakes much less than on an ICE car there will be proportionally less brake dust and a further reduction from using PSCBs will be pretty minor.

Personally I liked the looks (bigger brakes) of the PSCBs and the additional brake dust reduction is an added bonus and of course, I wanted the Mission-Es which dictate getting the PSCBs.

However, I don't plan on buying two cars, one with regular brakes and one with PSCBs just to test brake dust accumulation differences

 

[Jhenson29]

when I fly down an off ramp at 105mph and slow to 45mph, MOST of the braking action (greater than 70%?) is being generated from the mechanical brakes- can we all agree on that?

It depends on your rate of deceleration within those speeds, not the speeds themselves. Some quick not-double-checked math suggests you can do the decel with regen-only in 8 sec. Faster with other resistive forces like drag and rolling resistance.

 

[Jhenson29]

90% of braking (most of the time)

I think this is referring to 90% overall based on some model of an average or typical driver. Not necessarily 90% of any one (or all) instantaneous sample(s). If so, “most of the time” doesn’t make sense here and it would probably be 100% most of the time.

 

[daveo4EV]

Are you forgetting what you said? These forums man...it's really hard to not get salty.

You said, "on 90% regen braking is diminishing returns though, no?" referring to my post that claimed a 90% reduction in brake dust (Porsche claim). People make mistakes in their writing; however you seem to claim that regen would require less braking so less dust. That is not the case and certainly not practical.

The regen is NOT a replacement for brakes; not even close. Regen in the context of the Taycan barely offers a braking (aka slowing) function, therefore it does not reduce the need for brakes, therefore it does not reduce brake DUST.

The only cars that would offer less braking and therefore less dust, are cars with a one pedal driving option hence my earlier comments. Or of course, selecting options such as PSCBs or PCCBs.

Now I am rolling my eyes...seriously, as I am writing this, I am rolling my eyes.

you are fundementally confused - just because porsche doesn't do regen by lifting off the accelerator does _NOT_ mean there is no regeneration.

Porsche offers regeneration _WITH THE BRAKE_ pedal - they only "add/blend" in friction braking _IF NECESSARY_ to achieve greater deceleration based on you pressing harder on the brake pedal - it is entirely possible and often the case the Taycan is brought to a FULL stop using NOTHING BUT regeneration with the brake pedal - they even have a display on the dash showing the regeneration (the green bar from about 7 o'clock to 12 o'clock is the level of regeneration you are doing - only when you are at max "green" and then press harder are the friction brakes brough into the equation.

your arguments will continue to make no sense until you understand how Porsche has blended regeneration into the brake pedal.

unless you're braking really really hard - nearly all deceleration on the Taycan is handled by regen and friction brakes are "added" when "necessary" to achieve higher rates of deceleration based on driver's input (how hard you're pressing the pedal) - Taycan has the highest level of regen available in a production automobile on the market today - which means unless you are running around panic braking all hte time - most/nearly-all deceleration is handled entirely via regeneration.

the choice of "one pedal" driving is a user interface/driver interface software "trick" - and to date nearly every EV has and uses regeneration - the question is how does the driver "invoke" it

in the case of TEsla it's invoked by lifting off the accelerator and the brake pedal is 100% friction brakes

in the case of Porsche there is very very light regen from accelerator "lift off" - and brake pedal is regen until you press hard enough to also 'blend/add' the friction brakes.

Porsche could if they wanted to change the Taycan's software to offer one-pedal driving - say 40% regen on lift off the accelerator, and then the rest of regen with the brake pedal blended (they already do this today in existing shipping Taycans) - the Taycan's FULL regen power on accelerator lift-off would be too much…

it's all software, it's all adjustable - it's all a user/driver interface design issue - the Taycan is fundementally a regen-first friction-brakes 2nd blended braking vehicle by design - there is no way to avoid regeneration - and as stated unless you are braking really really hard - you are actually very very rarely using the friction brakes on the Taycan EVER...

in t

 

[daveo4EV]

MOST of the braking action (greater than 70%?) is being generated from the mechanical brakes- can we all agree on that?.

no we can not agree on that - because it's not true - the amount of friction braking depends on how hard you press on the pedal - the Taycan will FAVOR regeneration up to the point that it needs to "add" friction braking into the equation - you can fly off an offramp at 105 mph and press the brake pedal to slow down to 45 mph using NOTHING BUT REGENERATION and NEVER invoking the friction brakes

I encourage you to use the "power display" in your Taycan - and watch the green bar from 7 o'clock to 12 o'clock on hte main dash - if you are not maxing out the green bar (7 o'clock position) you're using 100% regeneration

the Taycan can be brought to full stop 90% of the time with out the friction brakes being used at all.

 

[wurzitup]

no we can not agree on that - because it's not true - the amount of friction braking depends on how hard you press on the pedal - the Taycan will FAVOR regeneration up to the point that it needs to "add" friction braking into the equation - you can fly off an offramp at 105 mph and press the brake pedal to slow down to 45 mph using NOTHING BUT REGENERATION and NEVER invoking the friction brakes

I encourage you to use the "power display" in your Taycan - and watch the green bar from 7 o'clock to 12 o'clock on hte main dash - if you are not maxing out the green bar (7 o'clock position) you're using 100% regeneration

the Taycan can be brought to full stop 90% of the time with out the friction brakes being used at all.

I guess you misunderstood my meaning........ fly off the offramp at 105 to 45 and very hard on the brakes......... yes, most of the braking force is mechanical. Not regenerative.
I don't know about you guys but I don't generally get off the highway at 105 gently or in 8 seconds........ ?

Sponsored