Regenerative Braking Drive Modes Gimmicky?

[NeilBlanchard]

Regen is better than coasting for recovering potential energy (going down hills) where coasting will result in higher average speed and more aero losses, though.

It all depends on what you need to do: if you want to carry speed (and you can) then coasting is best. Regen should only be used when you need to slow down.

Coasting has the lowest loss possible - and uses the kinetic energy to move the car forward. Regen can never regain all the energy (by definition) so it is better than friction brakes - but it cannot substitute for coasting.

Aero losses will always happen, so that is a red herring.

The other aspect of coasting is that you accelerate less - so you use significantly less energy, and then use the kinetic energy you have "invested" in the moving car in the best way possible. In B mode, you accelerate and then regen, so you use more energy, then lose more.

I don't disagree. Let me restate that I was referring only to "going down hills where coasting will result in higher average speed" e.g. any steep hill since one obviously can't alter the topography with their driving style.

I thought of another real world coasting-buster scenario: no traffic, travelling 55 mph, light turns red 1/8 mile up the road (or whatever particular distance a 55 mph e-golf would coast for). It's a long light... coasting all the way up without touching the brake is less efficient than regen braking hard and then travelling at a slow rate (~15 mph) before coasting to a stop; every moment spent at higher speed is more kJ being used to heat the air. Regen losses are quickly overcome with less energy lost in the air. Just a way of lowering average speed with little effect on travel time.

Right - WHEN you need to slow down, regen is great! There is regen integrated on the brake pedal in the e-Golf, which makes this really easy, and you can fine tune how much you slow down.

I only use the D1, D2, etc. for really extended downhills.

 

[ulrichw]

I think some people in this thread are hung up in ICE-land.

In an ICE car, you coast by lifting your foot all the way off the gas pedal.

In your e-Golf, you have a choice. You can have it behave like an ICE car by leaving it in D, or you can turn the "gas" pedal into a much more useful control that simultaneously lets you accelerate and decelerate by using one of the regen settings.

If you do the latter, then you coast by holding the pedal at the setting that generates 0 drive (i.e., when the needle of your power gauge is on 0). If you need a little deceleration, lift more. If you need acceleration, push down more.

I drive in B all the time, and after a short adjustment period, it seems like a much better way to drive than the old-fashioned way. I have no problems coasting. The brake/accelerator model seems a little bit like having two steering wheels - one to turn left and one to turn right.

Also, the way you control the speed doesn't perceptibly change whether you're going level, uphill or downhill, whereas with the brake/gas model you have to make more of an adjustment. If you're going uphill, lifting will decelerate you quite significantly, so you don't switch to the brake until you really need to slow down, while going down a steep hill, you accelerate even when completely off the gas, so you need to switch to the brake even if you just want to hold your speed. With the two-way pedal, your "zero point" changes, but when you're driving, the adjustment is completely intuitive - you don't even notice that the "hold my speed" point is at a different point in the travel of the pedal.

 

[dublectric]

I drive in B all the time, and after a short adjustment period, it seems like a much better way to drive than the old-fashioned way. I have no problems coasting. The brake/accelerator model seems a little bit like having two steering wheels - one to turn left and one to turn right.

Also, the way you control the speed doesn't perceptibly change whether you're going level, uphill or downhill, whereas with the brake/gas model you have to make more of an adjustment. If you're going uphill, lifting will decelerate you quite significantly, so you don't switch to the brake until you really need to slow down, while going down a steep hill, you accelerate even when completely off the gas, so you need to switch to the brake even if you just want to hold your speed. With the two-way pedal, your "zero point" changes, but when you're driving, the adjustment is completely intuitive - you don't even notice that the "hold my speed" point is at a different point in the travel of the pedal.

I agree 100%. I prefer to drive in B all the time: highway, around town, stop-and-go, you name it. Once you master being smooth with the accelerator pedal, there is no jerkiness; you can easily "coast" - as long as the consumption gauge on the left is pointing at zero, it's coasting, with exactly the same results as if you were in D with your foot off the accelerator.

One reason I prefer B over using the brake pedal for regen, is that when you use the brake pedal you're never sure when the friction brakes kick in. B mode allows you to avoid using the brake pedal for as long as possible, and you know that as long as your foot is off of the brake pedal, no friction braking is involved.

 

[bizzle]

I tried B like you guys are talking about and it seemed like a pain in the butt to keep it perfectly on 0. Seemed like a lot of hunting. I only tried it for a mile or so, though, and then was over the experiment.

Much easier to simply coast in D and flip the shifter to B like a manual downshift.
Incidentally, I find that as long as I keep the gauge around 2-4 in the green then I'm definitely not using friction pads. It might even be most of the green portion of the gauge but I can't say for certain.

 

[JoulesThief]

I tried B like you guys are talking about and it seemed like a pain in the butt to keep it perfectly on 0. Seemed like a lot of hunting. I only tried it for a mile or so, though, and then was over the experiment.

Much easier to simply coast in D and flip the shifter to B like a manual downshift.
Incidentally, I find that as long as I keep the gauge around 2-4 in the green then I'm definitely not using friction pads. It might even be most of the green portion of the gauge but I can't say for certain.

You don't really go into friction pad until you pin the needle at 6 in the green zone, except when slowing down from perhaps 10 to 7 mph down to a speed of 0.

I prefer to drive the same way as Bizzle. Down shift to "B" mode when I want brakes.

 

[dublectric]

I prefer to drive the same way as Bizzle.

That's cool... I'm glad VW provided options, giving the driver the choice of how to go about it.

 

[NeilBlanchard]

I think some people in this thread are hung up in ICE-land.

In an ICE car, you coast by lifting your foot all the way off the gas pedal.

No, lifting your right foot in an ICE slows the car by using the engine - which shuts off the fuel - but is not coasting, because the car is being slowed by the engine. So, most other EV's mimic this ICE behavior.

The e-Golf in D is like no other EV - and VW did this for a reason. It is more efficient.

By driving in D1, D2, D3, or in B, you are mimicking an ICE, with downshifting.

 

[forbin404]

I think some people in this thread are hung up in ICE-land.

In an ICE car, you coast by lifting your foot all the way off the gas pedal.

No, lifting your right foot in an ICE slows the car by using the engine - which shuts off the fuel - but is not coasting, because the car is being slowed by the engine. So, most other EV's mimic this ICE behavior.

The e-Golf in D is like no other EV - and VW did this for a reason. It is more efficient.

By driving in D1, D2, D3, or in B, you are mimicking an ICE, with downshifting.

You might want to look up 'Torque Converter' for ICE cars. That does allow coasting (well...there is a slight drag)

 

[bizzle]

I think some people in this thread are hung up in ICE-land.

In an ICE car, you coast by lifting your foot all the way off the gas pedal.

No, lifting your right foot in an ICE slows the car by using the engine - which shuts off the fuel - but is not coasting, because the car is being slowed by the engine. So, most other EV's mimic this ICE behavior.

The e-Golf in D is like no other EV - and VW did this for a reason. It is more efficient.

By driving in D1, D2, D3, or in B, you are mimicking an ICE, with downshifting.

You might want to look up 'Torque Converter' for ICE cars. That does allow coasting (well...there is a slight drag)

A coasting automatic transmission is meant to approximate a manual transmission in neutral.

While a torque converter may allow coasting in that way, it doesn't change the engine braking characteristics like coasting in D or switching between the regenerative modes do in our eGolfs.

 

[Golfcart]

I likes me my B mode for driving around town and my D mode for the freeway.

 

[dlaituri]

In my orientation session at the dealership, I think they captured it well - D modes are like various degrees of downshifting, B is like a secondary brake pedal.

I was also told when you take your foot off the pedal in B mode, the brake light comes on (haven't confirmed this)... and I've noticed stepping on the brake also increases the re-gen kw, suggesting braking with the pedal is a calculated combination of re-gen + pads & rotors.

Third observation - when the car is fully charged, D and B modes don't do much to slow the car - there's no place for the charge to go

My game: time hitting B mode at just the right point so the car comes to a stop at the right spot!

 

[JoulesThief]

In my orientation session at the dealership, I think they captured it well - D modes are like various degrees of downshifting, B is like a secondary brake pedal.

I was also told when you take your foot off the pedal in B mode, the brake light comes on (haven't confirmed this)... and I've noticed stepping on the brake also increases the re-gen kw, suggesting braking with the pedal is a calculated combination of re-gen + pads & rotors.

Third observation - when the car is fully charged, D and B modes don't do much to slow the car - there's no place for the charge to go

My game: time hitting B mode at just the right point so the car comes to a stop at the right spot!

I've learned to apply the "B" mode on and off, modulating as necessary to slow down enough before the red light, such that it turns green and I don't lose all forward momentum. Takes practice, but it's easily doable with some time behind the wheel.

 

[NeilBlanchard]

When you lift your right foot in an ICE - it slows the car with the engine, and it shuts off the fuel. That is not coasting.

You either have to push down the clutch pedal, and/or put it into neutral to coast.

The main thing about coasting is that it reduces the time that you use energy. Coasting has lower losses than regen, because regen cannot regain 100% of the energy. So, in D, you accelerate less, then coast, then use regen if you need to slow down.

Driving in D uses less energy to accelerate the car, then loses less by moving the car forward with the kinetic energy and avoiding regen loss. Then to slow/stop, you use regen instead of friction brakes.

 

[dlaituri]

Keep in mind that when you're in B mode, every time you take your foot off the accelerator, the brake lights come on. For someone following you, it can look like you're a crazy double-footer (left foot on the brake, right foot on the gas)...

 

[forbin404]

Keep in mind that when you're in B mode, every time you take your foot off the accelerator, the brake lights come on. For someone following you, it can look like you're a crazy double-footer (left foot on the brake, right foot on the gas)...

Just did that yesterday to a tail gater.
He was hanging too close, so I popped in 'B' and all of a sudden, poof, he backed off about 20 feet.

I call B mode Brake Check..haha

 

[Verkehr]

My car doesn't light up the brakes in B mode until around 1/3 regen but it also depends on the speed. I can see it at night because the glow from the CHMSL is visible in the rear view mirror. Overall I'm using the brake lamps less than in even a manual transmission vehicle.

 

[SJCyclist]

Why would you call one of the most unique features about the car "gimmicky"? Having the ability to adjust is fantastic and was a big selling point of the car for me.

 

[JoulesThief]

Why would you call one of the most unique features about the car "gimmicky"? Having the ability to adjust is fantastic and was a big selling point of the car for me.

Obviously, not everyone thinks like me, or like you. Different strokes for different folks.

 

[Jaysher]

I have had a question that I don't see discussed here:

Does it take more power/electricity to move the car forward in B mode than in D mode? Since B mode gives you that feeling of resistance/braking it seems like it would, but I'm not really sure how it works.

I often drive to the city, which is 60 miles on flat interstate with no traffic. In D mode is there really less resistance, so is it more efficient in energy use since there's no braking or downhill coasting?

That's what I do but I haven't tested the hypothesis. I pop it into 1,2 or B as soon as I approach the off ramp or any traffic.

BTW I use 1, 2 and B all the time in local driving - it's like a game to use them as much as possible and the brake as little as possible.

 

[JoulesThief]

I have had a question that I don't see discussed here:

Does it take more power/electricity to move the car forward in B mode than in D mode? Since B mode gives you that feeling of resistance/braking it seems like it would, but I'm not really sure how it works.

I often drive to the city, which is 60 miles on flat interstate with no traffic. In D mode is there really less resistance, so is it more efficient in energy use since there's no braking or downhill coasting?

That's what I do but I haven't tested the hypothesis. I pop it into 1,2 or B as soon as I approach the off ramp or any traffic.

BTW I use 1, 2 and B all the time in local driving - it's like a game to use them as much as possible and the brake as little as possible.

For the purposes of efficiency, and most miles per Kwh in your battery, I believe you have the right idea... use the shifter like an hand brake, modulate as necessary to maximize regeneration only when you need to brake, and use Drive mode the majority of the time.