One Pedal driving Mach-E? Are you a fan?

Are you a fan of one-pedal driving?


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zhackwyatt

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I would assume Model 3 is brake-by-wire due to Summon and all that.
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Nak

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I would assume Model 3 is brake-by-wire due to Summon and all that.
Nope. Tesla can "add"braking, but it can not reduce friction braking applied by the driver. "Brake By Wire" means you apply a certain amount of brake pedal travel and the car decides how much friction braking to apply and how much regen to apply. The Tesla master brake cylinder is a direct connection to the hydraulic brakes. An electric servo can add braking pressure to the master cylinder, but it can not reduce the friction braking applied by the driver. It technically could add friction braking pressure, but does so only in an emergency. It could add regen braking as well, but only does so--at this time--based on accelerator pedal position, not brake pedal position. The car behaves this way in order to maintain braking feel for the driver. If you have a Tesla you can verify this easily. Simply set regen to coast and release the accel pedal. Note the green bar which is your regen indicator. Now do the same thing from the same speed, but apply the brake pedal. You will see that the green bar indicates the same regen as before. Yes, the AS system can reduce brake pressure applied by the driver, but only to prevent wheel skid.
 

Nak

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Nope. You get the same regen whether or not you press the brake pedal. Lifting the accel pedal is what activates regen. When you push the brake pedal in a Tesla you are directly and mechanically applying pressure to the master cylinder which directly and mechanically applies hydraulic pressure to the Brake cylinders. The car's computer has no ability to reduce brake pressure except to reduce wheel skid. This is a simple fact. The presence of anti-skid does not imply "brake by wire." The only way a braking system could behave in the manner you describe is "Brake by wire." Brake by wire by definition means there is no mechanical connection between the brake pedal and the brake cylinders. Rather "brake by wire" means--by definition--that the brake pedal activates a sensor, the sensor provides information to a computer, and the brake cylinders are applied by the computer. This is not the case with Tesla, or for that matter the vast majority of vehicles today--if any. There are some that initial brake pedal movement results in regen activation by the computer, but further brake pedal movement mechanically activates the brakes. The Tesla is not one of these vehicles. Regen may be applied in the Tesla, but it is the lifting of the accel pedal that tells the computer to apply the regen, not the brake pedal. There is NO physical way the computer in a Model 3 can delay the application of the friction brakes for any reason at all. (Other than anti-skid.) Again, it is a mechanical connection and there is no mechanism installed that would give the computer this kind of control. This is simple fact, not opinion.
 

Nak

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Interesting. Mine doesn't do that. What mode are you in; I'll try it in your mode. Regardless though, the computer can't limit friction braking. There's no mechanism for it to do so. Technically, though, it could add regen with the brake pedal. I've not seen it, but of course I could be mistaken on that count. I'll check again as soon as I know what mode you've seen this behavior in.
 

FredT

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You will only be correct if initial brake application is "Brake by wire" on the Taycan. I doubt it is, but I admit I don't know. If the initial brake application is brake by wire, then the brake feel is going to be different when the battery is cold or full. It doesn't seem to me that would be something Porsche would do, but again I don't know. I'm curious, does anyone here actually KNOW, or is everyone just assuming they know how the Taycan's brakes work? If you KNOW, then how about a link? I mean, it's a silly argument because the answer isn't a matter of opinion, it's a simple fact. I for one don't know what that fact is, I'm just guessing.
I too doubt that Porsche is using brake-by-wire, few cars do it seems, but I don't believe that it is necessary. For example, Audi braking is purely regenerative up to a braking limit of .3 g, and mechanical brake is not applied until that is exceeded, whether you are using the brake pedal or not. Kona is apparently .25 g, same effect. Do you doubt that most of the Taycan braking comes from regen? Porsche claims that 90 percent of it does.
 


Nak

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Do you doubt that most of the Taycan braking comes from regen? Porsche claims that 90 percent of it does.
I have not studied the Taycan's braking system so I have no idea whatsoever. I'm just curious if anyone here has any factual information on the subject. I'm not saying anyone has that information, nor am I implying that no one has that information. I really don't know nor do I have enough reliable information to have an informed opinion. I'm just curious. I do have to say though that that your stated brake level on the Audi must be speed dependent. It is physically impossible for the Audi to regen brake at .3g all the way down to zero.
 

Nak

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Since you didn't post what braking mode you were using I went out and tested every possible combination. (There are two brake settings on the Model 3.) Sorry, but you are mistaken. There is no combination of braking modes where pressing on the brake pedal has any effect whatsoever on the amount of regen applied. Other than as you slow down, regen decreases as it becomes less effective. The ONLY pedal in the Model 3 that has any effect on regen is the accelerator pedal.

I know I've been rude to you in the past LYTMCQ, and I apologize for that. I have to say though--and I'm not trying to be rude--but for someone who owns a Model 3 you seem to know remarkably little about it, other than what can be found on posts on the internet.
 

buzznwood

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Sorry Fred, you're not making sense. Let me try again to explain it.

The Taycan only recaptures energy when the brake pedal is pressed.

One-pedal driving modes recaptures energy whenever you lift off the accelerator.
The taycan actually has a few modes for PRM only when it is set to off will you get coasting, otherwise you will get moderate regen when you lift off, there is also an auto mode which has adaptive regen using the cameras to adjust the amount.

As long as we have options I am fine, I am in the porsche camp for how it comes to set up the braking so hopefully the mach-e will have similar.
 

Shihear

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I too doubt that Porsche is using brake-by-wire, few cars do it seems, but I don't believe that it is necessary. For example, Audi braking is purely regenerative up to a braking limit of .3 g, and mechanical brake is not applied until that is exceeded, whether you are using the brake pedal or not. Kona is apparently .25 g, same effect. Do you doubt that most of the Taycan braking comes from regen? Porsche claims that 90 percent of it does.
Actually, Taycan does use brake-by-wire. It's mentioned in these reviews https://www.cnet.com/roadshow/news/porsche-taycan-first-ride/
https://www.caranddriver.com/reviews/a29208876/2020-porsche-taycan-turbo-s-drive/
 

Nak

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"When the brake-by-wire controller engages the conventional friction binders for more aggressive deceleration, it does so by imperceptibly blending the two systems. " Very interesting. I would have thought for safety's sake all vehicles still would have a mechanical connection to the brakes. Man, it is amazing how fast technology is moving. I wonder if you push the brake pedal far enough you still engage the brakes mechanically? I would think that would be a requirement... Blow a fuse and no brakes? I did read an article in Motor Trend where the author said he could feel the switch from regen to friction. MT Article
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