One pedal braking

[bbulkow]

All things being equal, you will use less brake pad material with 1PD driving.

https://www.energy.gov/energysaver/one-pedal-driving-explained#:~:text=The Benefits of One-Pedal Driving&text=One-pedal driving helps your,lost while coasting and braking.

That page is optimistic at best and misleading at worst. Sorry, department of energy. But the detailed section about 1PD mostly gets it right: it's just a preference. You *might* be doing more coasting with the 1PD interface, or you might not, depending on how you've been trained and your driving style. It's likely, if you're a standard American driver, that 1PD will induce you to "coast" more, but that's very different than saying 1PD doesn't engage the brakes when braking with the accelerator. Maybe the optimistic way to say: that page, as written is what I would call "directionally accurate and factually false", in that it will likely cause the reading audience to do the right thing (turn on 1PD, coast more), even if some of the points are misleading.

There's an argument that a skilled operator can "coast" more with 2PD, because (essentially) that coasting range is broader, and you've got more subtlety through the range of the accelerator. I haven't found that true in practice. In my experience, with our vehicles, the sensitivity settings allow you to pick and match your driving style. Turning on power meter and seeing when you're in regen is the way to improve your driving style, and pick a mode that matches the driving and traffic you encounter. I'm talking about whisper / normal / unbridled.

In our cars, the acceleration system is "fly by wire", and any input to increase or decrease speed gets translated into changes in the braking / propulsion system.

If the car can provide the necessary braking through regen, it will. If it can't, it actuates the brakes. This decision is independent of whether you "input" your requirements through 1PD or 2PD.

Let's take an extreme case: you're going down a really long hill (say, I80 westbound after the Donner summit in California), and you gently hit the accelerator because you wish to accellerate. This may not engage the drive system: it may engage the regen system less : which allows gravity to accelerate the car.

Similarly, if you're travelling fast enough, and you pull up on the accelerator *in 1PD or 2PD mode*, you may go past the limits of regen and need to engage the physical brakes.

The car will make this decision based on how much deceleration it needs at a given moment, and even the state of charge / temp / etc. In one of my electric devices (an "electric unicycle" or EUC) which only has regen braking, the device can't brake effectively with full state of charge (no place to put the electrons ), and there's insufficient top-end buffer designed, so people advise not charging 100% so the brakes work all the time, or at least, being very wary in the first few miles if you are at 100% charge. Not an issue with our better-designed EV cars.

Our EVs have deep buffers at the top, and physical brakes, but you get my point. The car figures how how much power the regen system can handle, and past that, applies the brakes - IN BOTH 1PD and 2PD.

Again, all this becomes super transparent if you turn on the on-dash power meter, which is why I get a little wordy whenever this topic comes up. I've turned this on, and it's an eye opener. It's really, really obvious what the car is doing: you hit the limits of regen on the screen. If you're used to driving a Tesla, they have the same basic 1PD / 2PD algos (although with different constants), same as any EV, except Tesla's power meter is on by default, and actually shows you (via a bar that starts out Green when you're in regen and goes grey) when the physical brakes engage. Drive a Tesla for a few days, watch the power meter, play with 1PD / 2PD, it's all very obvious.

By default, we MachE drivers get battery coach, which is a really dumbed down version of the power meter and after the fact. With the power meter, you can see that applying more braking later keeps you in regen: which is what the EPA points out too: coasting as long as you can get away with is optimal, especially at higher speeds.

I even find, at freeway speeds, that in 1PD if I tap the brakes to disengage Blue Cruise, I eng up going beyond the capabilities of regen - something that doesn't happen in 2PD. I've trained myself to put my foot lightly on the accelerator, use the left "engagel/cancel" button to disengage BC, significantly before my offramp. Then I can coast into offramp speed while staying within regen. Again, all very easy to see if you turn on the power meter (grr Ford! Please enable for all!)

If you don't want to go through the hassle of modding your car (it's a 1 bit config change.... Crazy.... I can only imagine Tesla has a patent or something), an OBD2 scanner app should show the same thing: basically you'll see where the (negative) power tops out. There might - must really - be an OBD2 exposed variable to display how much the physical brakes are applied at a given moment, I haven't found it yet. Then you could see visually and trivially when you're going outside of regen, and train your driving habits.

Finally, it stands to reason that AWD models, and ER models, can supply more regen. Had I considered this, I would have probably bought an AWD. AWD is supposed to have worse range, but even now there's scant data on real world differences. The EPA tests almost certainly don't go into how effective and efficient the regen system is, but I suspect it has important impact on real-world range. The AWD build should have greater ability to regen, just like it has greater ability to accelerate. I wonder if, for example, I could normally get out of bluecruise with a brake tap if I had the AWD model.

It also stands to reason that a GT will have even greater ability to regen. It's even possible that in 1PD on a GT its virtually impossible to apply the physical brakes : but my point is the brake decision by the control software is *informed by* but *independent from* the 1PD / 2PD decision.

Thanks for listening. Sorry for the wall of text.

TL;DR - can we please stop saying that 1PD doesn't engage the brakes?

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[Old_Norm]

That page is optimistic at best and misleading at worst. Sorry, department of energy. But the detailed section about 1PD mostly gets it right: it's just a preference. You *might* be doing more coasting with the 1PD interface, or you might not, depending on how you've been trained and your driving style. It's likely, if you're a standard American driver, that 1PD will induce you to "coast" more, but that's very different than saying 1PD doesn't engage the brakes when braking with the accelerator.

There's an argument that a skilled operator can "coast" more with 2PD, because (essentially) that coasting range is broader, and you've got more subtlety through the range of the accelerator. In my experience, with our vehicles, the sensitivity settings allow you to pick and match your driving style. Turning on power meter and seeing when you're in regen is the way to improve your driving style, and pick a mode that matches the driving and traffic you encounter.

In our cars, the acceleration system is "fly by wire", and any input to increase or decrease speed gets translated into changes in the braking / propulsion system.

If the car can provide the necessary braking through regen, it will. If it can't, it actuates the brakes. This decision is independent of whether you "input" your requirements through 1PD or 2PD.

Let's take an extreme case: you're going down a really long hill (say, I80 westbound after the Donner summit in California), and you gently hit the accelerator because you wish to accellerate. This may not engage the drive system: it may engage the regen system less : which allows gravity to accelerate the car.

Similarly, if you're travelling fast enough, and you pull up on the accelerator *in 1PD or 2PD mode*, you may go past the limits of regen and need to engage the physical brakes.

The car will make this decision based on how much deceleration it needs at a given moment, and even the state of charge / temp / etc. In one of my electric devices (an "electric unicycle" or EUC) which only has regen braking, the device can't brake effectively with full state of charge (no place to put the electrons ), and there's insufficient top-end buffer designed, so people advise not charging 100% so the brakes work all the time, or at least, being very wary in the first few miles if you are at 100% charge. Not an issue with our better-designed EV cars.

Our EVs have deep buffers at the top, and physical brakes, but you get my point. The car figures how how much power the regen system can handle, and past that, applies the brakes - IN BOTH 1PD and 2PD.

Again, all this becomes super transparent if you turn on the on-dash power meter, which is why I get a little wordy whenever this topic comes up. I've turned this on, and it's an eye opener. It's really, really obvious what the car is doing: you hit the limits of regen on the screen. If you're used to driving a Tesla, they do the same thing (all EVs will), except Tesla's power meter is on by default, and actually shows you (via a bar that starts out Green when you're in regen and goes grey) when the physical brakes engage. Drive a Tesla for a few days, watch the power meter, play with 1PD / 2PD, it's all very obvious.

By default, we MachE drivers get battery coach, which is a really dumbed down version of the power meter and after the fact. With the power meter, you can see that applying more braking later keeps you in regen: which is what the EPA points out too: coasting as long as you can get away with is optimal, especially at higher speeds.

I even find, at freeway speeds, that in 1PD if I tap the brakes to disengage Blue Cruise, I eng up going beyond the capabilities of regen - something that doesn't happen in 2PD. I've trained myself to put my foot lightly on the accelerator, use the left "engagel/cancel" button to disengage BC, significantly before my offramp. Then I can coast into offramp speed while staying within regen. Again, all very easy to see if you turn on the power meter (grr Ford! Please enable for all!)

If you don't want to go through the hassle of modding your car (it's a 1 bit config change.... Crazy.... I can only imagine Tesla has a patent or something), an OBD2 scanner app should show the same thing: basically you'll see where the (negative) power tops out. There might also be a variable to display how much the physical brakes are applied at a given moment, I haven't found it yet.

Finally, it stands to reason that AWD models, and ER models, can supply more regen. Had I considered this, I would have probably bought an AWD. AWD is supposed to have worse range, but even now there's scant data on real world differences. The EPA tests almost certainly don't go into how effective and efficient the regen system is, but I suspect it has important impact on real-world range. The AWD build should have greater ability to regen, just like it has greater ability to accelerate. I wonder if, for example, I could normally get out of bluecruise with a brake tap if I had the AWD model.

Thanks for listening. Sorry for the wall of text.

TL;DR - can we please stop saying that in 1PD you don't engage the brakes?

Thank you for the informative (and lengthy explanation). But do you have any actual non-anecdotal citation that states the 2PD reduces brake pad wear as well as or better than 1PD? I haven't found one. BTW, in one PD (barring an emergency stop) you don't engage the brakes but the car may.

 

[bbulkow]

Thank you for the informative (and lengthy explanation). But do you have any actual non-anecdotal citation that states the 2PD reduces brake pad wear as well as or better than 1PD? I haven't found one. BTW, in one PD (barring an emergency stop) you don't engage the brakes but the car may.

No, I didn't say I had any data that 2PD or 1PD reduces brake pad wear. Sorry if I was unclear, my point specifically was I think that statement in the quoted EPA page is likely misleading / wrong and I also can't find any data to back up that statement. I agree with you. Nor does the EPA page say it anywhere other than the opening, which I find troublesome: seems like bad edit work?

My point is it's very individual based on training, car model, preferences, traffic patterns.

Whether it is true *in aggregate* is probably unknowable and not very interesting: what's interesting each of us driving for more regen / less brakes, and that comes from turning on the power meter on your car, eyeballing when you're in regen with your settings on your roads, and making your own decision. Because more range and less pads is a very, very good thing!

Coasting to reduce pad wear has always been a thing. On older non-drive-by-wire, larger displacement, manual transmission cars, "engine braking" was always more accessible, and acts more like 1PD on an EV. I was trained to use that, and always had very high pad life on my ICE vehicles - I think 1 got to 100k miles on most of my pads - maybe which this seems especially silly to me. If you were trained well to drive on ICE vehicles, you're already using the same principles. I find 1PD like a breath of fresh air, a return to driving a manual tranny muscle car, but I also realize peeps trained to drive automatic transmissions will find 2PD more comfortable. If anything, driving my CRV is now unsafe, it takes me a few blocks to remember coasting is not a thing with a small displacement CVT-equipped ICE vehicle, so far I haven't ploughed into anything before I reset my brain. Mostly the CRV gathers more and more dust.

My point is the same, although the words are longer, than most people posting here too: it's preference. I'm just using a ton more words to say it. I'll stop now.

 

[Old_Norm]

No, I didn't say I had any data that 2PD or 1PD reduces brake pad wear. Sorry if I was unclear, my point specifically was I think that statement in the quoted EPA page is likely misleading / wrong and I also can't find any data to back up that statement. I agree with you. Nor does the EPA page say it anywhere other than the opening, which I find troublesome: seems like bad edit work?

My point is it's very individual based on training, car model, preferences, traffic patterns.

Whether it is true *in aggregate* is probably unknowable and not very interesting: what's interesting each of us driving for more regen / less brakes, and that comes from turning on the power meter on your car, eyeballing when you're in regen with your settings on your roads, and making your own decision. Because more range and less pads is a very, very good thing!

Coasting to reduce pad wear has always been a thing. On older non-drive-by-wire, larger displacement, manual transmission cars, "engine braking" was always more accessible, and acts more like 1PD on an EV. I was trained to use that, and always had very high pad life on my ICE vehicles - I think 1 got to 100k miles on most of my pads - maybe which this seems especially silly to me. If you were trained well to drive on ICE vehicles, you're already using the same principles. I find 1PD like a breath of fresh air, a return to driving a manual tranny muscle car, but I also realize peeps trained to drive automatic transmissions will find 2PD more comfortable. If anything, driving my CRV is now unsafe, it takes me a few blocks to remember coasting is not a thing with a small displacement CVT-equipped ICE vehicle, so far I haven't ploughed into anything before I reset my brain. Mostly the CRV gathers more and more dust.

My point is the same, although the words are longer, than most people posting here too: it's preference. I'm just using a ton more words to say it. I'll stop now.

Thanks again. The issue is, I've had a few people reply to my post (#80) in which I simply said, "All things being equal, you will use less brake pad material with 1PD driving." Thus my the question about citations regarding 2PD driving being as good as or better regarding brake pad wear. Since my comment was on brake pad wear I was relying on this comment for the DoE, " One-pedal driving helps your brakes last longer because you’re not using them much. EVs use regenerative braking like hybrids and plug-in hybrids and capture the kinetic energy typically lost while coasting and braking. " I assume you are not saying that statement is wrong. Again, thanks for the input.

 

[JamesStew71]

> Is it worth it?

None of the drivers of my Mach E like it / use it. The accelerator is for go and the brake is for stop, as every vehicle I have ever driven since a child has been.

we use ours always, only at a carwash do we turn it off

 

[Machinator]

All of this is really interesting. I see under general topics there is a thread “most eco-mode“ where someone did an experiment and found the different modes of driving and one pedal didn’t make a huge difference. My biggest concern after reading all of this is how to do the brake lights respond to one pedal versus two pedal. Might have someone follow me while we’re on a cell phone to see if they report a difference.
My biggest problem with the Mach e is that I am absolutely obsessed with it and how it works and how to be the most efficient I can. ?. I’m worried I’m going to start a fight with one of these insufferably superior Tesla drivers.

 

[Old_Norm]

All of this is really interesting. I see under general topics there is a thread “most eco-mode“ where someone did an experiment and found the different modes of driving and one pedal didn’t make a huge difference. My biggest concern after reading. All of this is how to do the brake lights respond to one pedal versus two pedal. Might have someone follow me while we’re on a cell phone to see if they report a difference.
My biggest problem with the Mach e is that I am absolutely obsessed with it and how it works and how to be the most efficient I can. ?. I’m worried I’m going to start a fight with one of these insufferably superior Tesla drivers.

How Does One-Pedal Driving Work?

• The accelerator pedal serves both accelerating and braking, although you can still rely on your brake pedal in any situation for safety reasons.
• There is an on and off button to activate single-pedal driving, located near the gearshift in some electric cars.
• Move your foot forward to accelerate the vehicle just as you normally would. To slow down, simply lift off the pedal.
• Before stopping, take your foot off the gas and allow the vehicle to slow down naturally to a complete stop. If you stop accelerating, the one-pedal will automatically slow and stop the car for you. If you misjudge for any reason, you can also use your brake pedal.
• Depending on preference, drivers can adjust the one-pedal function in some cars, so the braking period is shorter or longer.
• As you get used to the one-pedal driving, you’ll start to judge the distance of when you need to remove your foot from the accelerator pedal to allow the car to come to a complete stop on its own.
• After stopping completely, the EV remains in that position automatically during a one-pedal drive. In some EVs, it stops in place on inclines, too.
• Brake lights on your electric car will automatically illuminate when you decelerate the vehicle and will remain on when the vehicle fully stops.
• The single-pedal driving will not work when you’re in “park” or “neutral.”
• If your car comes equipped with an enhanced or adaptive cruise control system and you turn it on, the one-pedal driving will not function because it doesn’t need to.
• If you need a tow or go to an automatic car wash, some EV carmakers suggest you turn off the one-pedal function.

 

[Old_Norm]

I’m worried I’m going to start a fight with one of these insufferably superior Tesla drivers.

At my age, this is about how a fight between me and a Tesla owner would go.

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