Driving in 'L' mode

[drgnfish]

Is there a way to have the break light turn on while driving in 'L' mode. I believe that current when you let go of the gas the break light current do not turn on. Its a safety issue when you're driving in 'L' mode and you let go of the 'gas' peddle the break light should turn on to alert other behind you.

 

[dan2112]

The brake light does come on when you are driving in L and let off the accelerator. People here say it comes on when decelerating at 0.1G or more. It does go out when you stop or go under 5 mph (I think, but not sure). You do have to put your foot on the brake when you are stopped. I use it all the time in stop and go traffic and at night I can see the reflection of my brake light on the car behind me.

 

[drgnfish]

I had my wife watch the break lights while I pulled in the garage I might have been going under the 5 mph. Thanks for the clarification.

 

[dan2112]

Well it would be nice to get clarification from GM as to when the lights do come on. Just passing on my experience...

 

[ChevyCustomerCare]

Is there a way to have the break light turn on while driving in 'L' mode. I believe that current when you let go of the gas the break light current do not turn on. Its a safety issue when you're driving in 'L' mode and you let go of the 'gas' peddle the break light should turn on to alert other behind you.

Hi drgnfish,

So sorry for the delay in getting this information for you. Your Bolt EV is designed to turn on the brake lights when regeneration torque is sufficient enough to create decelerating greater than approximately 0.10g. This can occur while using the regen paddle, driving in "L" Mode or both.

Feel free to send me a private message if you have additional questions/concerns.

Warm Wishes,

Amber G.
Chevrolet Customer Care

 

[phil0909]

...decelerating greater than approximately 0.10g. This can occur while using the regen paddle, driving in "L" Mode or both.

Thanks for the info, Amber.

Can regen torque produce the necessary 0.10g deceleration in "D" mode? At highway speeds, D can produce substantial regeneration. It would be helpful to confirm that the brake lights are never activated by regen in D.

Also, how does the Bolt inform the driver that regen torque deceleration has exceeded approximately .10g and activated the brake lights? I have not found any accelerometer reading or brake light indicator on the dashboard.

Your assistance is appreciated.

 

[abaiwadhwa]

I have noticed that in when the car is going downhill. At which point car will automatically put the parking brake on. I think it is a nifty feature.

 

[flamaest]

And here is the problem: ""It does go out when you stop or go under 5 mph""

GM sells this car as 'one-pedal' driving, so I do not touch the brake when stopped.

All the nay-sayers can chime in if they like, but GM SELLS this feature prominently, and one-pedal driving implies NO BRAKE PEDAL IS USED.

I am waiting for a rash of rear-end collisions due to this.

The brake light should stay on in L mode until the gas pedal is touched again. PERIOD.

This was car SOLD as being OTA upgradable. FIX THIS GM.

 

[BerkeleyBowlt]

I am waiting for a rash of rear-end collisions due to this.

The brake light should stay on in L mode until the gas pedal is touched again. PERIOD.

One thing to consider is that the way it works now is exactly the same as the way a manual transmission car works. Once you've stopped the car, the brake lights turn off unless you are pressing down on the brake pedal. The resting "stopped" L state is similar to the state of a manual transmission car with the clutch depressed and no foot on the brake.

Or, looked at another way: In any other car, the brake light is on only when the driver has his or her foot on the brake and the brake is actually engaged. To me, it would seem unusual if Chevy showed brake lights to other drivers even when the brake is not engaged.

 

[Maxters]

I am waiting for a rash of rear-end collisions due to this.

The brake light should stay on in L mode until the gas pedal is touched again. PERIOD.

One thing to consider is that the way it works now is exactly the same as the way a manual transmission car works. Once you've stopped the car, the brake lights turn off unless you are pressing down on the brake pedal. The resting "stopped" L state is similar to the state of a manual transmission car with the clutch depressed and no foot on the brake.

Or, looked at another way: In any other car, the brake light is on only when the driver has his or her foot on the brake and the brake is actually engaged. To me, it would seem unusual if Chevy showed brake lights to other drivers even when the brake is not engaged.

To me it's also more like driving a manual. It would be weird for brake lights to show when not being pressed.
It surprised me a little that they have the brake lights show on regen decel. I agree it's safer, but I can slow down pretty fast downshifting a diesel.

A neat feature would be to have the option of "Brake Light when regen paddle held" ..

 

[Wookie]

I am waiting for a rash of rear-end collisions due to this.

The brake light should stay on in L mode until the gas pedal is touched again. PERIOD.

Is there a rash of rear-end collisions involving manual transmission cars that have been around for 100 years?

If you have been keeping your foot on the brake when stopped since you started driving, why change that now?

If you get rear ended, without your foot on the brakes, you will rear-end someone in front of you, or worse, get pushed into cross traffic and get t-boned.

 

[oilerlord]

And again, the truth is somewhere in the middle.

Mercedes dialed in my car's regen just about right. It isn't nearly as abrupt (read: dangerous on icy roads) as a BMW i3, but it isn't a freewheeling coast either. I'd guess that I'm doing one-pedal driving about 70% of the time. With that said, my brake lights don't turn on when I lift off the throttle - ever. I have seen people behind me get closer than they used to then they have with any of my former manual transmission cars . On several occasions (mostly this winter), I have tapped the brakes to let people know that I'm slowing down.

Sure, engine braking with a manual has the same effect (no brake light) but manual transmission cars are becoming quite rare, and not everyone that drives a manual exclusively uses engine braking (or knows how to do it).

The fact that the brake lights do come on with the Bolt when they need to should put this "issue" to rest.

 

[flamaest]

My opinion is that everyone is right here, and to that end, Chevy should abandon the "one-pedal driving" marketing statement since this promotes the reduced usage of brake pedal.

Official "Chevy Bolt one-pedal driving" marketing video:

https://www.youtube.com/watch?v=-sH-tvEE8aM

My personal thoughts are that, if the brake lights come on "at all" when one-pedal driving, the they should fully implement this model so that the brakes are also applied at a stop, until the gas pedal is touched again. I am sure this will draw a whole other list of comments as to why this is not possible/safe, so I refer back to my first note which is to abandon the marketing statement.

I can see how someone might take the one-pedal driving notion seriously, and so they might make into the snopes hall of fame: www.snopes.com/autos/techno/cruise.asp . Insert chuckle.

 

[phil0909]

they should fully implement this model so that the brakes are also applied at a stop, until the gas pedal is touched again.

I agree, this is the best approach. But the current Bolt implementation is adequate - not ideal, but I don't think it creates any big dangers.

 

[oilerlord]

I'd be interested to read owner feedback if driving in "L" is more or less efficient than "D". Sure, L gives more regen but also brakes harder and kills momentum. In terms of hypermiling, I've always gone with coasting in "N", preserving momentum whenever possible (and safe) to do so...the reasoning being that regenerative braking only recovers a fraction of the energy that was used to get the car up to speed.

 

[phil0909]

L gives more regen but also brakes harder and kills momentum.

No, there is no trade-off there. L does not kill momentum except when you want it to kill momentum, e.g. when you are approaching a red light. If you want to maintain momentum, you do that easily by keeping the accelerator depressed to just the degree you require.

I don't think L necessarily gives more regen than D either - that is, regen is typically the same whether you use D plus (blended) brake or L (with or without the blended brake). The brake pedal also produces regeneration (instead of friction) for some or all of its stopping power.

I personally don't care about shaving a fraction of a percent off fuel usage, but if I had to guess, I would say driving in L is very slightly more fuel efficient than driving in D. This would be because in L you are maybe slightly more likely to avoid use of the friction brakes in some situations. But it would have to be a very small difference overall.

The above is based on what I've read (mostly unofficial) about the Bolt's blended braking, and seen in my driving in both L and D. I'd defer to anyone with greater knowledge on the subject, but from what I can tell, choosing L or D should be based on preference, not energy efficiency.

 

[LeftieBiker]

Higher regen modes like "L" or "B" generally produce better energy economy in stop and go or low speed 'slow and go' driving, but low regen modes are better for highway use. It's pretty hard to constantly modulate the pedal in these modes to make regen optional, so most people just change modes when they aren't needed.

 

[oilerlord]

No, there is no trade-off there. L does not kill momentum except when you want it to kill momentum, e.g. when you are approaching a red light. If you want to maintain momentum, you do that easily by keeping the accelerator depressed to just the degree you require.

You're right of course...and it doesn't take long to get the hang of coasting in neutral, and modulating the brakes with the accelerator pedal. Perhaps I'm picking nits, but even with my car's mild regen, it becomes tiresome trying to find the full-coast neutral position with the accelerator. Often times, I invariably end up braking when I don't necessarily want to, so for me; I wish my car had a mode that completely turned off accelerator pedal braking to preserve the car's momentum.

I'm driving a near 4000 pound car with only 28 kWh to work with so driving for efficiency is part of the deal if I want to turn 87 EPA miles into 100 or more. I think Bolt drivers trying to hit the 300 mile mark on a charge would probably prefer a pure-coasting setting when lifting of the throttle too.

 

[phil0909]

You're right of course...and it doesn't take long to get the hang of coasting in neutral, and modulating the brakes with the accelerator pedal. Perhaps I'm picking nits, but even with my car's mild regen, it becomes tiresome trying to find the full-coast neutral position with the accelerator. Often times, I invariably end up braking when I don't necessarily want to, so for me; I wish my car had a mode that completely turned off accelerator pedal braking to preserve the car's momentum.

I'm driving a near 4000 pound car with only 28 kWh to work with so driving for efficiency is part of the deal if I want to turn 87 EPA miles into 100 or more. I think Bolt drivers trying to hit the 300 mile mark on a charge would probably prefer a pure-coasting setting when lifting of the throttle too.

I have no need of, nor interest in, the 300-mile mark, but I would also like a pure coasting option. Since Bolt does not have that option, I just always use L. I got used to it quickly and do not find it tiresome on the freeway. I suppose if it ever did get tiresome, I'd just turn on the cruise control. So for me, coasting is not needed, but would be nice to have.

 

[boltage]

Higher regen modes like "L" or "B" generally produce better energy economy in stop and go or low speed 'slow and go' driving, but low regen modes are better for highway use. It's pretty hard to constantly modulate the pedal in these modes to make regen optional, so most people just change modes when they aren't needed.

If the regular brake pedal uses regen exclusively when pressed lightly, then it should theoretically be possible to drive with the same acceleration/deceleration/economy in D versus L. But you would use different accelerator and brake pedal inputs to get the same acceleration/deceleration in D versus L.

    Max Brake                     Coast      Max Acceleration
         |                          |            |
         |Friction Brake|Regen Brake|Acceleration|
D mode   |<------Brake Pedal---->*<-Accelerator->|
L mode   |<-Brake Pedal->*<-----Accelerator----->|

In the above diagram, * represents what you get when neither the brake pedal nor accelerator is pressed. Pressing the accelerator all the way to the floor gives maximum acceleration on the right in both modes; pressing the brake pedal as hard as possible gives maximum braking on the left in both modes. But other use of the accelerator and brake pedal result in different operation between the two modes.

The button behind the steering wheel adds another option to use heavy regen braking in either mode. The sport mode button presumably remaps the accelerator input so that a light press indicates a higher level of desired acceleration than in non-sport mode.

Of course, you can still use L mode for typical purposes like controlling speed down a hill.