Highway - Low or Standard Braking?

[jcal0820]

Trying to get some fresh, new opinions and suggestions on this.. when on the freeway/highway, is it more efficient to use Low Regen braking, or the default Standard, which has more aggressive regen braking esp since the v9 software update? The Standard mode doesn’t seem to allow for coasting, which added miles on my old Camry Hybrid. I also wish my Model 3 cam with a regen ‘toggle’ like some other EV’s, instead of having to dig into the Driving menu and switch back and forth thru the touchscreen, very distracting.

 

[Drizzle]

Without knowing how tesla executes the regenerative braking, there isn't much to discuss but the facts.

A 4,000 lb vehicle stopping 100 ft in 1 second produces the same amount of energy as it would stopping 100 ft in 10 seconds.

What I assume standard and low regen breaking does is change the amount of time it takes to stop.

What's awesome is that this is simple enough to measure during your daily commute if you use the highway

 

[swaltner]

Low is “more efficient” in that the Wh/mile rating will be lower. It’s not lower because it’s better at recouping energy, it’s better because your average speed is lower. (numbers here are made up, but examples) If I want to exit the highway and only use low regen, I must disengage cruise control and start slowing down 1/2 mile from the stopping point. If regen is set to standard, I disengage the cruise control 1/4 mile from the stopping point. This means that when set to low, you stopped consuming energy to propel the car 1/4 mile earlier. Do that enough times and your energy use drops considerably, but your average speed is also dropping.

Your throttle pedal is a rheostat, not a toggle switch. You can coast in an EV, but you can’t let off the throttle to do it. Look at the dash as you slightly press on the throttle. You can easily hold your foot on the throttle to perfectly coast (no regenerative braking and no propulsive power either / on the Model 3: no green/black bar right below the speedometer). Just set the regen to max (standard) and modulate the throttle to however fast you want to decelerate in that particular instance. The only time I don’t have regen set to the maximum setting on an EV is in icy conditions, but I almost always have my foot slightly on the throttle to keep the EV from slowing at its maximum regen braking capability.

 

[1.21GW]

It is highly related to the control you have on your foot.

For example regen recovers ~50% of the energy to slow down but you need to use 100% of the energy to speed back up. The more times you slow down and speed up, the higher the losses.

It doesn’t matter what setting you have it on (not significantly anyhow) based on physics. But the low setting may be more forgiving on the driver with a twitchy foot.

 

[derotam]

Low is “more efficient” in that the Wh/mile rating will be lower. It’s not lower because it’s better at recouping energy, it’s better because your average speed is lower. (numbers here are made up, but examples) If I want to exit the highway and only use low regen, I must disengage cruise control and start slowing down 1/2 mile from the stopping point. If regen is set to standard, I disengage the cruise control 1/4 mile from the stopping point. This means that when set to low, you stopped consuming energy to propel the car 1/4 mile earlier. Do that enough times and your energy use drops considerably, but your average speed is also dropping.

Your throttle pedal is a rheostat, not a toggle switch. You can coast in an EV, but you can’t let off the throttle to do it. Look at the dash as you slightly press on the throttle. You can easily hold your foot on the throttle to perfectly coast (no regenerative braking and no propulsive power either / on the Model 3: no green/black bar right below the speedometer). Just set the regen to max (standard) and modulate the throttle to however fast you want to decelerate in that particular instance. The only time I don’t have regen set to the maximum setting on an EV is in icy conditions, but I almost always have my foot slightly on the throttle to keep the EV from slowing at its maximum regen braking capability.

Disagree with your first paragraph, agree with the second. It is more nuanced than that, you can't say that the difference between low and standard regen directly transfers into your idea of disengaging cruise at 1/2 or 1/4 mile respectively. I don't think there is a starting speed where it would be true because the regen is not a linear function.

I definitely agree with you about using the throttle to coast in the Model 3, I do it all the time. Low regen is good for those who can't/don't want to manage it as much, but I would say that using low regen in a lot of cases will just increase brake usage.

 

[ewoodrick]

Coasting does not provide any regen, even on the Camry, where what you were getting is lite braking.

Regen is always better for power than braking.

Lite/No regen is better for true coasting, well, actually no acceleration or braking is costing.

 

[jcal0820]

When 'coasting' (on low regen braking mode), I see the regen occurring below the speedometer, indicated by the long 'green' line, which gets longer when on a decline. Will try to imitate this on Standard mode, with light push on the accelerator. Just seems easier to do under the 'Low' regen setting.

 

[Msjulie]

Will try to imitate this on Standard mode, with light push on the accelerator. Just seems easier to do under the 'Low' regen setting.

Practice makes perfect, then getting in an ICE car feels so weird.

 

[mswlogo]

Without knowing how tesla executes the regenerative braking, there isn't much to discuss but the facts.

A 4,000 lb vehicle stopping 100 ft in 1 second produces the same amount of energy as it would stopping 100 ft in 10 seconds.

What I assume standard and low regen breaking does is change the amount of time it takes to stop.

What's awesome is that this is simple enough to measure during your daily commute if you use the highway

Hmmm, I never considered low was just tilting the curve over the same area.

But how many opportunities (on average) are there in the 100ft in 10 seconds case to not need to use the brake.

I would think brakes would be needed way less often (on average) in the 100 ft in 1 case.

 

[derotam]

When 'coasting' (on low regen braking mode), I see the regen occurring below the speedometer, indicated by the long 'green' line, which gets longer when on a decline. Will try to imitate this on Standard mode, with light push on the accelerator. Just seems easier to do under the 'Low' regen setting.

Yes it is easier because the regen curve is not as forceful, but personally I like to have the more forceful regen available in case i need it which I do almost everyday when people slow down too fast in stop and go traffic.

 

[Needsdecaf]

I haven't taken delivery of my Model 3 yet but I just wanted to chime in to comment that as a person who has been on automotive forums since 2004, I have to say it's so nice.......

TO SEE SOMEONE FREAKING SPELL THE WORD BRAKE CORRECTLY!!!!

That is all. Carry on.

 

[jcal0820]

Yes it is easier because the regen curve is not as forceful, but personally I like to have the more forceful regen available in case i need it which I do almost everyday when people slow down too fast in stop and go traffic.

...this is something I’m noticing more on the freeways out here. I could be ‘coasting’ for miles and then suddenly and instantly end up in stop & go, bumper to bumper congestion out of nowhere. Would be a pain to keep going into the touchscreen to change out the regen braking modes for every situation.

 

[derotam]

...this is something I’m noticing more on the freeways out here. I could be ‘coasting’ for miles and then suddenly and instantly end up in stop & go, bumper to bumper congestion out of nowhere. Would be a pain to keep going into the touchscreen to change out the regen braking modes for every situation.

You won't be coasting for miles unless you are going down hill for miles. Coasting meaning no regen and NO energy to the motor. Your rolling resistances at a minimum will be slowing you down...like in an ICE car when you let off the gas pedal.

You don't need to change your braking modes, adjust with your foot and watch the energy bar. Obviously if you aren't up to that task or find it too cumbersome or just don't want to do it, then great set your regen to however you like it.

Your original post said that Standard regen doesn't allow for coasting, it does. even in low regen when you let off the accelerator all the way you are not true coasting, you are using regen, just not as much as in standard. To actually coast, meaning slowing down based on natural resistances of the vehicle(no regen) you have to do the same thing whether in low or standard regen.

 

[jcal0820]

Have a simple solution.. will just use the speed modulated cruise control (don't have Autopilot) on the freeway/highways

 

[Snow Drift]

I love standard regen. The control allowed with just your ankle is amazing. It’s like driving my manual car in 1st gear at all times, but without the speed restriction. Plus on the highway you would definitely want full braking force if you get cut off.

I am able to keep my foot down on the pedal, yet not pressed enough to induce the black line. So I am in theory “coasting,” without slowing or speeding up. Then as I push slightly more the black line appears and the car accelerates. Very little input is needed on the highway for cruising.

...or you can mash it for fun.

 

[mswlogo]

Without knowing how tesla executes the regenerative braking, there isn't much to discuss but the facts.

A 4,000 lb vehicle stopping 100 ft in 1 second produces the same amount of energy as it would stopping 100 ft in 10 seconds.

What I assume standard and low regen breaking does is change the amount of time it takes to stop.

What's awesome is that this is simple enough to measure during your daily commute if you use the highway

Thinking of this a little further. If what you say is true and we ignore the statistical aspect of which mode would typically get better utilized (see my prior reply).

I wonder if regen is set on low and your battery is in partial regen mode that you'd get more energy back into the battery. Because it's less Peak Watts from regen on low but the battery can accept lower watts over a longer period of time (when it's cold).

You'd think this would be automatically done when the Regen is on Standard and your battery in Partial Regen mode though.

 

[Timothyj999]

...Your throttle pedal is a rheostat, not a toggle switch. You can coast in an EV, but you can’t let off the throttle to do it. Look at the dash as you slightly press on the throttle. You can easily hold your foot on the throttle to perfectly coast (no regenerative braking and no propulsive power either / on the Model 3: no green/black bar right below the speedometer). Just set the regen to max (standard) and modulate the throttle to however fast you want to decelerate in that particular instance. ....

It’d be a useful option for the accelerator to have an indicator at this sweet spot (either a haptic detent that your foot could feel, or a more obvious feature on the display) , so you wouldn’t have to constantly monitor the discharge/regen line. Maybe a “coast” option?

 

[jcal0820]

Think other EV's might have this or similar setting