Model S Brake & Accelerator Pedal Positions

[Alpha]

Yes I did hear the chime, but stopping power was definitely not nearly powerful enough under the circumstance.

As soon as you depress the brake while also depressing the accelerator, motor torque is cut. There is also a double chime/dong sound and a message is displayed on the driver information display. If you have firmware version 4.3 or later, you will have the brake override.

For this to work you have to depress the brake, though. I almost drove over a jogger in a Prius once when the sole of my dress shoe caught behind the brake pedal. The only way to prevent this is to use your left foot for braking, and your right foot for accelerating. This is what I have done since the jogger incident.

 

[eledille]

The only way to prevent this is to use your left foot for braking, and your right foot for accelerating. This is what I have done since the jogger incident.

This is not recommended, because when panicing, people tend to stretch both legs forwards to brace for impact. That would depress both pedals. It won't be a problem in Model S, though, as it cuts power when both pedals are depressed.

Yes I did hear the chime, but stopping power was definitely not nearly powerful enough under the circumstance.

Does it cut the regen? Even though the driver is actually (unintentionally) requesting torque, I think it should regenerate instead when both pedals are depressed.

 

[Alpha]

Yes it seemed like it cut the regen. The bottom line was the car wasn't stopping! And I had to take other evasive maneuvers to avoid an accident.
Now I drive barefoot or just with a sock and that seems to help a lot. I need to do some controlled experiments.

This is not recommended, because when panicing, people tend to stretch both legs forwards to brace for impact. That would depress both pedals. It won't be a problem in Model S, though, as it cuts power when both pedals are depressed.



Does it cut the regen? Even though the driver is actually (unintentionally) requesting torque, I think it should regenerate instead when both pedals are depressed.

 

[Rowlock]

I think Tesla may have addressed this question in the latest cars. I just took delivery of a P85+, and the brake pedal is significantly closer to the driver than the accelerator. Makes a huge difference, compared to the side-by-side position in the car I test-drove in May.

I put a picture at the bottom of my delivery experience thread. See if this looks different to your pedals:

http://www.teslamotorsclub.com/showthread.php/17974-An-interesting-factory-delivery-day

I'm not pressing the accelerator there, just resting my foot on the pedal so you can see how far back it sits.

 

[derekt75]

I think Tesla may have addressed this question in the latest cars. I just took delivery of a P85+, and the brake pedal is significantly closer to the driver than the accelerator. Makes a huge difference, compared to the side-by-side position in the car I test-drove in May.

I put a picture at the bottom of my delivery experience thread. See if this looks different to your pedals:

http://www.teslamotorsclub.com/showthread.php/17974-An-interesting-factory-delivery-day

I'm not pressing the accelerator there, just resting my foot on the pedal so you can see how far back it sits.

That picture looks the same as on mine (VIN 2826 from December). If you press hard enough to brake hard with your foot half on the brake and half on the go pedal, you'll press both.

Compare that to my SLK32:

On that car, you can press the brake really hard without that foot being able to press the go pedal. Unfortunately, you need to really lift your foot off of the go pedal to get to the brake. I much prefer Tesla's design, even if it results in the occasional beep beep beep.

...
Back in my Model S, I tried pressing hard on both pedals today coming off of the freeway. For well over a second, the motor was outputting substantial power (> 80kW) while the mechanical brake was slowing the car. I stopped two footing it before any interlock kicked in.
I also tried driving around a parking lot. There, it seemed like the motor was limited to about 4kW when the brake was pressed. I don't really know what logic the car uses to limit electric torque, but it's not as simple as (if ((brake) && (e_power > 4 kW)) {e_power = 4 kW}). I'm not sure it should be that simple, but personally, I don't have a use case for the brake dissipating 120 kW while the motor is adding 80 kW.

 

[ckessel]

Managed to hit both pedals while slowing for a stop light and it definitely cuts some of the stopping power when that happens. I nearly rear ended the guy in front of me before lifting my foot and panic stomping the brake. Would have been a low speed hit at that point, but the behavior as it is today definitely isn't desirable. It's completely freaky for it to suddenly have less stopping power after the alarm goes off.

 

[Alpha]

You see! That's what I'm talking about. I routinely take my shoes off when driving now - haven't had an issue that way. Makes it much easier to feel what's going on with my feet. I emailed Elon a very detailed account of the problem but got no response. I imagine he probably didn't read it (probably gets 10K or more emails a day I would guess.) Or if he did read it, he likely just forwarded it to an engineer. But I would really really hate for someone to have a bad accident because of this...

 

[derekt75]

You see! That's what I'm talking about. I routinely take my shoes off when driving now - haven't had an issue that way. Makes it much easier to feel what's going on with my feet. I emailed Elon a very detailed account of the problem but got no response. I imagine he probably didn't read it (probably gets 10K or more emails a day I would guess.) Or if he did read it, he likely just forwarded it to an engineer. But I would really really hate for someone to have a bad accident because of this...

yeah, I don't have a problem, myself [so far], but if even 5% of users are getting substantial positive electric torque when they want to be braking, it's a big problem.
I think they should fix this in software (e.g., brake limits electric power to a few kW), but it seems to me that they need a fix.

 

[tezco]

I didn't notice a problem until I broke out the sandles this summer. I haven't had trouble stopping, but often I feel a subtle surging when at a full stop and both pedals are depressed. I've only activated the chime and error message once, though.

On the other hand, I had a scary episode last winter in my Leaf. Had the rubber overshoes on and stepped on the gas to pull out of my driveway onto the very busy 55 mph street that I live on. Not enough room for that wide of a shoe so both pedals went down and the car pulled out in front of traffic, but I only had about 5% power. Was nearly rear-ended.

 

[J in MN]

... but if even 5% of users are getting substantial positive electric torque when they want to be braking, it's a big problem.

So, now that I have access to my own Model S, I was able to test this.

I did 9 combinations: 30 mph, 50 mph and 70 mph, each with acceleration at 30 kW, 60 kW and max. In every case the outcome is exactly same: Motor power immediately drops to zero, and the double chime sounds. I should add that at max power, it takes about 0.2 seconds for power to drop all the way to zero, but it's not clear if this is a deliberate ramp down, or just an artifact of the display (smoothing).

So, there is no longer any doubt. The car cuts power upon brake application.

Now, the thing that I think is creating the perception in some people that it does not cut power, is the fact that motor power drops to zero, so at that point you only have friction brakes, no regen. All of us that drive with the regen setting in standard have been trained to expect 0.15 g of deceleration when lifting off the accelerator, and so we expect at least that much deceleration when pushing the brake pedal. But at the same time, regen has trained us not to stomp on the brake pedal in the way that we have to on an automatic transmission gasoline car. So you are left with the false perception that the car is not stopping, when in fact, you just need to be more deliberate.

So, it may be interesting to have a discussion on whether the brake override should be programmed to engage full regen instead of just a power cut. I don't know what the best option from a human machine interface perspective would be. Personally I like it the way it is, but I can see that people who don't think about this stuff may find it more intuitive to have full regen, or at least be consistent with their regen setting. But that doubles up the validation testing that Tesla will need to do, and may not comply with FMVSS.

 

[wycolo]

[tezco] whew!!

My Road Rulez:

While negotiating PLEASE have BOTH feet on respective pedals yes, with chimes ringing. Drag the brakes & feather the accel pedal. Avoiding metal-to-metal is what its all about!!

While driving, don't have tunes on, rather listen to the environs & the car. Scan from shoulder to shoulder across highway. Don't daydream. Drive like you were on a motorcycle, completely exposed from all angles.

They will get you, just a matter of time!!

 

[stevezzzz]

So, now that I have access to my own Model S, I was able to test this.

I did 9 combinations: 30 mph, 50 mph and 70 mph, each with acceleration at 30 kW, 60 kW and max. In every case the outcome is exactly same: Motor power immediately drops to zero, and the double chime sounds. I should add that at max power, it takes about 0.2 seconds for power to drop all the way to zero, but it's not clear if this is a deliberate ramp down, or just an artifact of the display (smoothing).

So, there is no longer any doubt. The car cuts power upon brake application.

But (and this is where people are taken by surprise) there is an in-between condition where you can press lightly on both pedals simultaneously, applying both friction braking and traction power, before triggering the audible warning. It happens to me several times a week, but only occasionally do I get the warning.

 

[ckessel]

I can see that people who don't think about this stuff may find it more intuitive to have full regen, or at least be consistent with their regen setting.

Thanks for testing it. My suspicion was the regen got cut.

It's definitely counter intuitive for the stopping power to suddenly lessen when this emergency override cuts in, so I'd very much vote for leaving regen on rather than cutting it when this happens.

 

[derekt75]

So, now that I have access to my own Model S, I was able to test this.

I did 9 combinations: 30 mph, 50 mph and 70 mph, each with acceleration at 30 kW, 60 kW and max. In every case the outcome is exactly same: Motor power immediately drops to zero, and the double chime sounds. I should add that at max power, it takes about 0.2 seconds for power to drop all the way to zero, but it's not clear if this is a deliberate ramp down, or just an artifact of the display (smoothing).

So, there is no longer any doubt. The car cuts power upon brake application.

Now, the thing that I think is creating the perception in some people that it does not cut power, is the fact that motor power drops to zero, so at that point you only have friction brakes, no regen. All of us that drive with the regen setting in standard have been trained to expect 0.15 g of deceleration when lifting off the accelerator, and so we expect at least that much deceleration when pushing the brake pedal. But at the same time, regen has trained us not to stomp on the brake pedal in the way that we have to on an automatic transmission gasoline car. So you are left with the false perception that the car is not stopping, when in fact, you just need to be more deliberate.

So, it may be interesting to have a discussion on whether the brake override should be programmed to engage full regen instead of just a power cut. I don't know what the best option from a human machine interface perspective would be. Personally I like it the way it is, but I can see that people who don't think about this stuff may find it more intuitive to have full regen, or at least be consistent with their regen setting. But that doubles up the validation testing that Tesla will need to do, and may not comply with FMVSS.

Coming off a freeway, I pressed significantly on both pedals and got the chime. I was decelerating while the display showed an accelerating power of 80 kW. Pressing harder on the go pedal increased the display power and decreased my acceleration. I was using an earlier version of v4.5.

I guess at this point I'd like to hear someone from Tesla explain what's going on: why was my experience the opposite of J's? Did J stomp his brake pedal while I only pressed it enough to bleed off about 100 kW? Is this a FW thing? What gives?

 

[SigS905]

My car is currently in the shop for something similar to the second days test drive at the Factory last year. Stopped at a light, traffic moved forward, checked left for traffic as I proceeded, saw that the driver in front of me had stopped. Paniced stomp on brake resulted in both pedals being pressed. Result was damage to the whole front as I went under the vans bumper. Would never have happened except for both pedals were pressed at once. Been driving the Model S for 21680 miles prior to that.

 

[pilotSteve]

My car is currently in the shop for something similar to the second days test drive at the Factory last year. Stopped at a light, traffic moved forward, checked left for traffic as I proceeded, saw that the driver in front of me had stopped. Paniced stomp on brake resulted in both pedals being pressed. Result was damage to the whole front as I went under the vans bumper. Would never have happened except for both pedals were pressed at once. Been driving the Model S for 21680 miles prior to that.

Wow, this is significant! I too (like most everybody) have gotten the beeps from occasional both pedal presses. Its just going to happen now and then due to the pedal positions IMO in spite my best efforts. To have this happen and not have the torque cut off is a serious design issue. Thanks for posting this, I believe Tesla needs to address this in a serious way.

 

[SigS905]

Wow, this is significant! I too (like most everybody) have gotten the beeps from occasional both pedal presses. Its just going to happen now and then due to the pedal positions IMO in spite my best efforts. To have this happen and not have the torque cut off is a serious design issue. Thanks for posting this, I believe Tesla needs to address this in a serious way.

The beeping had happened to me before a number of times. The issue was the spacing. This happened in less than 30 feet.

 

[DrComputer]

Like I said when I first got my car and noticed this problem, this is going to be a big liability issue for Tesla if they don't fix the problem and do a retroactive fix for ALL delivered cars. This isn't just a "small annoyance" problem, it is a large safety issue.

 

[J in MN]

I guess at this point I'd like to hear someone from Tesla explain what's going on: why was my experience the opposite of J's? Did J stomp his brake pedal while I only pressed it enough to bleed off about 100 kW? Is this a FW thing? What gives?

This is indeed curious. Are you able to replicate this behaviour consistently? If so, take it in - there may be a hardware issue on your car.

In my testing I pushed very lightly on the brake pedal, just enough to trigger the power cut, not enough to result in significant loss of speed.

 

[derekt75]

Coming off a freeway, I pressed significantly on both pedals and got the chime. I was decelerating while the display showed an accelerating power of 80 kW. Pressing harder on the go pedal increased the display power and decreased my acceleration. I was using an earlier version of v4.5.

I guess at this point I'd like to hear someone from Tesla explain what's going on: why was my experience the opposite of J's? Did J stomp his brake pedal while I only pressed it enough to bleed off about 100 kW? Is this a FW thing? What gives?

just tried this morning with my latest v4.5 (1.33.54 I think).
At higher speeds, getting the chime cuts the power.
At low speeds (0-5 mph or so), I can get at least 10 kW of power with the brake on.

I'm happy.

I swear that's not what happened when I tried a few weeks ago.