I fully agree. The way GM has setup the braking maximizes regeneration no mater what mode you drive it in.

I watched the recent motortrend video where they brought the Bolt EV to Tesla. And the Tesla people wondering why the car can't be in L all the time and clearly not understanding at all how the brakes work on the Bolt EV.

 

....they brought the Bolt EV to Tesla. And the Tesla people wondering why the car can't be in L all the time and clearly not understanding at all how the brakes work on the Bolt EV.

Funny! They need to get out of their ivory towers more often..

... Single pedal driving is more work and I get plenty of regen in two pedal. I find I drive smoother and get more range in D. ....

Exactly ! It's more work, and for what? The '1 Pedal' driving experience?
You have to keep your right foot planted on that GO Pedal for the entire trip.

With Chevy EV's you can have it both ways!

Sometimes a Gentleman has to shift his butt or make an 'adjustment'.
Hey, Tesla and i3 drivers: We know what you are doing when your brake lights come on and you slow down for no apparent reason.

...I will say with Tesla and the best brakes, are you sure they're referring to the "experience" and not performance whether shortest stopping distance or fade?

Don't know, don't care.
I'm talking about the gushing reviews about all-things-Tesla and never actually comparing engineering details with other EV options.

(Engineering detail: stopping distance is a product of tire traction and weight of the vehicle. If dinky little discs can bring a car to the onset of ABS, the brakes are doing their job.
Of course brake fade from flogging the brakes repeatedly is another matter.)

 

I'm going to presume the Bolt's brakes work in the same manner as the Spark's. With 30K on our Spark EV I can say that blended braking is THE way to go. Single pedal driving is more work and I get plenty of regen in two pedal. I find I drive smoother and get more range in D. L is great for going down steep hills but other than that, not for me.

I was astounded when I found out that Tesla didn't offer blended braking.

 

Agree with you fully Norton...

I will say with Tesla and the best brakes, are you sure they're referring to the "experience" and not performance whether shortest stopping distance or fade?

 

An interesting detail from Car and Driver's raw track testing sheets for the Model S60 in 2014 and the Bolt EV recently is that while the S60 stopped slightly shorter the first time it experienced some brake fade and after 2-3 emergency stops it took longer than the Bolt because the Bolt showed no brake fade. I'm guessing the Bolt's lack of brake fade is due to a substantial part of the braking being done through regeneration rather than friction even during hard stops.

 

Interesting observation. Looking at the Bolt EV test datasheet, the stopping distances actually decreased by a few feet over those 6 stops.

During panic stops the regenerative braking does have a minor effect on the brake energy needed to be absorbed by the friction brakes. But it may be less than you expect. Physics follows...

Assumptions:
3760 lbs
70-0 mph panic stop
no aero drag or other deceleration forces
regen averages 45 kW (a guess, it may start at 60kW but trails off as the car slows)
deceleration duration of 3 seconds
friction and regen brakes are applied at same time at start of deceleration

The total kinetic energy removed to stop the car is E = 1/2 * m * v^2, where:
m = 3760lb = 1705.507 kg (includes driver weight)
v = 70 mph = 31.2928 m/s

E= 835MJ or 232Wh

The regen brakes would remove 38Wh from the car [45kW * 3 sec/3600*1000]. So the regen brakes absorb 16% [38/232] of the kinetic energy and the friction brakes absorb 84% [194/232].

If we rerun all the numbers with a heavier car like the S 60 (4800 lbs), and leave everything else the same, the regen and friction brake usage changes to 13% and 87%, respectively.

So the friction brake design has by far the biggest effect on fading during repeated panic stops. The differences in regen brake calibration between EVs will only have a small effect on brake fading.

 

The Volt/Bolt method of taking your foot off the accelerator to push the brake pedal to start deceleration, means you waste a fraction of a second to start slowing down. At higher speeds, this could mean 20-30 feet of additional stopping distance wasted. It could mean the difference of just scaring the crap out of yourself along with the pedestrian carrying a baby across the street and a horrible accident with your face all over the news for killing two people.

The Tesla one-pedal driving IMMEDIATELY starts deceleration when you take your foot off the accelerator.

Why would you want something else? With the Tesla, you set "Standard Regeneration" in the dash and it stays that way. If you want something like that on the Bolt, you have to select it every time you go for a drive. Oh, and if you remember to reach for the regen paddles during an emergency situation, you'll get that but only if you're going in a straight line. Good luck keeping that paddle pressed while you're turning the wheel to avoid something. And like several reviewers have said, big ugly shifter on a modern EV is stupid.

 

>The Volt/Bolt method of taking your foot off the accelerator to push the brake pedal to start deceleration, means you waste a fraction of a second to start slowing down. At higher speeds, this could mean 20-30 feet of additional stopping distance wasted. ...
The Tesla one-pedal driving IMMEDIATELY starts deceleration when you take your foot off the accelerator.
Why would you want something else? ....

>>Good luck keeping that paddle pressed while you're turning the wheel to avoid something. .....

>Why? Because it's the way cars have always been driven. There is no learning curve required. It's less work.
Someone could hop in a Chevy EV and immediately drive it just like a normal car.
Can't do that in a Tesla. You experience the 'Herky-Jerky' for a while. FUN !

If I need more braking than the 60kW of regen I get from the brake pedal of my little Spark EV, I have a seamless transition to friction brakes.
My foot is already on the Brake Pedal, just like a normal person, no "fraction of a second" if more braking is needed.

BTW, 60kW is the same amount of regen you get from a Tesla, but just on the rear wheels on a 1 motor model.
I suspect that has to be limited, on slick curves for example.

>>I agree about the regen paddle. It's 'Feature Creep'. Who needs it? It just complicates things. You don't want to burden the driver with thinking about how to slow down. It should come naturally.

Unfortunately Tesla didn't use their engineering to create a Blended Brake Pedal.
Drivers are forced to adopt this new "1 Pedal" driving style, and the associated last moment jabs at the brake pedal when 60kW of regen is not enough.

 

I'm not sure the Bolt and the Volt's braking is as bad as Chris TX is describing it. In fact, some comments make me wonder if Chris TX actually owns a Volt. I start up my car, set my mode to Sport and pull the selector back to L. Done. If I'm cruising and need to slow down, I simply relieve pressure on the accelerator, and the car starts to brake immediately. The way Chris TX is describing GM's braking setup reminds me of the way Rush Limbaugh described the "burden" of plugging our cars in every night.

 

Why would I lie about having a Volt? Do you seriously just not get on these forums enough to see what I do for other people's Volts, both Gen1 and Gen2? Feel free to click on the links in my sig. You might even see a few pictures of my Volt. I'm going off MY experiences with BOTH my Volt and Tesla. Driving the Volt in D, there is a delay in braking once you start letting off the gas. That delay isn't there with my Tesla that's always in "Standard Regen." That delay also exists in normal cars. What's wrong with removing that delay with the "one-pedal driving?"

Sure, go ahead and put your Volt in L and Sport everyday. But for the vast majority of people just want to put the thing in Drive and start driving, and like Norton points out, that's what they're going to do. Now, relying on the one-pedal driving for emergency situations isn't realistic and people will slam on the brake pedal with their foot.

Just do "one foot" emergency stopping maneuvers in D and then L while driving ~60MPH. See what the stopping distances you get with those tests. Do it three times in D and three times in L and average both sets. Make sure the brakes are cooled off between runs so there's no brake fade, which isn't an issue in emergency situations. You can't sit there and say there's not going to be a difference between the two sets.

 

I think it is great the options we are getting in the Bolt. Sounds like Chevy really listened and provided features for us geeks to geek out on, but also the option to "just drive" like any other car. Win-Win. Stuff like the paddle for regen is fun, and potentially helpful on hills. I have a modified gen1 Honda Insight with a "paddle" for regen on demand and I love it. I also like that in my modified Insight I can turn regen OFF to actually gain speed while coasting downhill when desired. To me the ability to turn regen off on demand is just as important. Any hypermiler will tell you... coasting, neither consuming nor regenerating power is the greatest boost to extending range.

 

Nobody said you were lying, Chris TX. My point is that you are describing how "inferior" the Volt's regenerative braking is compared to the Tesla's because Tesla defaults to your preferred while you literally have to hold the shifter a tenth of a second longer in the Volt (to put it in L). You are the only Volt owner I know who brings this up as an issue, but if you look at the results of impartial testing, your Tesla and Volt stop within 10 feet of each other in emergency braking (60-0 mph).

 

One thing I can see in videos, the Bolt EV doesn't have a standard shifter; you do not need to shift it to park to exit the vehicle...

 

Well, I asked Chevy Communications for clarification on the 9-6-16 Press Release linked above.
After a few emails back and forth here is the word from HQ:

Bill – Happy to review the facts described in the referenced press release. In answer to your questions:

> Are you saying the Bolt DOES NOT have the blended brake pedal exactly like the Volt and the Spark EV?
Correct - Bolt EV brake pedal operates hydraulic brakes and does not have a blended braking system.

> You get NO varying Regen when using the brake pedal?
There is some benefit, as result of decel, until brake pedal depressed hard enough

> You are forced to adopt to this new ‘1 Pedal’ driving style if you want to take advantage of regen?
The Bolt EV offers benefit from regen in default ‘D’ and every time accelerator input is removed and before brake pedal is depressed (described above). If owners/drivers who are comfortable with a more aggressive regen braking feel so choose, you can capture even greater benefit from regen by:
• engaging ‘L’ mode
• depressing the Regen on Demand paddle (on steering wheel)
• or do both
In any of these three latter modes, the regen is enough to bring vehicle to a complete stop. The use of the hydraulic brakes (the pedal) remains an option at all times.

Feedback from many Volt owners, who we learned enjoyed utilizing L in their vehicles and Regen on Demand Paddle (in Gen 2 Volt) to maximize regen benefit, led our team to improve upon that functionality for Bolt EV.

Thanks for your feedback and I’ll pass it along to our engineering team.

Fred Ligouri
Chevrolet Communications