Drive option that better incorporates neutral/coasting

My Nissan Leaf Forum

Help Support My Nissan Leaf Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

jlsoaz

Well-known member
Joined
Jul 8, 2012
Messages
849
Location
Southern Arizona, USA
Some drivers seem to be getting significantly higher efficiency from their vehicles by coasting in neutral on the highway and elsewhere. They do this by holding the stick to the N position for a couple of seconds. When they are ready to go back into drive, they simply switch it into drive with the stick.

My suggestion is that Nissan engineers investigate what some Nissan drivers have found and identify if there is a way to better automate this procedure so that other drivers who are not willing or interested in manually shifting to and from neutral while at speed can also experience these efficiency benefits.

Perhaps a way to do this would be to set up a drive option such that stepping on the accelerator pedal results in acceleration, but letting off the accelerator pedal completely results in simply coasting in neutral with no braking (0 regen braking, and 0 engine braking). This is just one idea among several. If Nissan engineers did investigate and then conclude that it might be worthwhile to try to automate the procedures of the Leaf-coasters, then they would likely want to look into several options that point, so the initial idea should not be taken as anything other than one possible path among many.

Notes:

1. Some drivers are of the view that the presently-available feature of feathering the pedal toward neutral power (0 kW) is nearly as good as a proposed feature of a more stable neutral capability over longer distances. I do not share this view, so I am suggesting Nissan engineers investigate if there are significant efficiency gains to be had by automation of the more stable neutral capability.

2. It is illegal in some states to coast in neutral and, aside from the legality, there are multiple arguments that coasting in neutral is not considered safe. The rationale(s) for the laws and safety considerations appear to include:
a) some considerations that are mooted by the Leaf's different engineering (for examples: a HCV might cut out power to steering or other systems if it stalled while coasting, and an HCV's system is "taken out of gear" when in neutral so that a level of control over the vehicle is lost, while a Leaf's system is different) and
b) some considerations that still might be relevant to driving a Leaf (keeping one's speed close to steady/constant in consideration of safety for other drivers might be somewhat difficult, and driving in neutral removes a bias toward lowered speed which some might consider to be a safety feature).

Leaf drivers who have driven extensively using the method of manually switching back and forth between Neutral and ECO indicate that in their view their driving methods are safe.

Altering the Leaf to automate the method of coasting without giving up energy would seem to hold some potential for mooting some of the safety debate and for delivering dramatic energy savings to a broader spectrum of Leaf drivers who may not have the desire to practice such specialized methods for attaining higher efficiency. It might also result in significantly better range and mpge ratings from the EPA and their counterpart European and ASOC agencies. On the other hand, if is possible that upon investigation/testing it might be determined that it is actually not a good idea from a safety standpoint to implement automation of coasting/neutral.
 
jlsoaz said:
Some drivers seem to be getting significantly higher efficiency from their vehicles by coasting in neutral on the highway and elsewhere. They do this by holding the stick to the N position for a couple of seconds.
Actually, we move the stick to "R". The car will beep at you and go immediately to neutral, no waiting necessary.
:)
 
It would be great to have a no regeneration switch. With it on you gain no energy, with it off you then gain as much as the modes you are in allow.

Another reason to have this ability is to not charge the battery when you are already at 100% charge, and going downhill. Or when you are at 80% charge and want to prolong your battery life by not charging it to over 80%.
 
These should be preference options, perhaps activated by the driver's RFID number.

Some want more regen with foot-off driving, others want less.
Make it a variable preference setting.

The same with a variety of other parameters,...
Like the "fixed" 77 degree F Heat-to temperature setting.
 
garygid said:
These should be preference options, perhaps activated by the driver's RFID number.

Some want more regen with foot-off driving, others want less.
Make it a variable preference setting.
[...]

Several good ideas here in this thread.

Does anyone know if other EV manufacturers (Tesla? Honda?) offer a hassle-free energy-saving ability to coast in neutral and then go back to instant-on power as needed? Is this part of how Honda is able to attain excellent mpge? I would be surprised if nobody had implemented this at all in that it just seems kind of obvious that it could help increase overall range for all drivers without adding kWh and cost.

Come to think of it, I was a bit surprised when I first tried the D mode and it felt like letting off the accelerator didn't result in going to 0 kW power expenditure.... ? I haven't had time to step out and research this, but I don't think it does.

I think it's important that Nissan give serious consideration to the various ways to implement this, and then - if it becomes clear that efficiency and range could be readily increased for all drivers - explore a way that would be clear and easy enough so that it might get their EPA range number up.
 
jlsoaz said:
Come to think of it, I was a bit surprised when I first tried the D mode and it felt like letting off the accelerator didn't result in going to 0 kW power expenditure.... ? I haven't had time to step out and research this, but I don't think it does.

I think it's important that Nissan give serious consideration to the various ways to implement this, and then - if it becomes clear that efficiency and range could be readily increased for all drivers - explore a way that would be clear and easy enough so that it might get their EPA range number up.
It sounds like you haven't looked at the power use screen, or even the bubbles in the dash that indicate power use.

When you lift your foot in either D or ECO you begin to regenerate power, rather than use it. By using ECO it is easier to let off a little to get to a no power use state than in D, but either mode is capable of this. In ECO the regeneration rate is higher than in D. The power use screen is the best way to see this.

The Tesla has all the regen available on the power pedal. Many people never even have to use the brake, and it takes a little getting used to since the regen is so heavy. Not too sure about the others.
 
jlsoaz said:
...Does anyone know if other EV manufacturers (Tesla? Honda?) offer a hassle-free energy-saving ability to coast in neutral and then go back to instant-on power as needed? Is this part of how Honda is able to attain excellent mpge? ...
The Honda Fit EV does not go to neutral, but in the ECON mode, with Drive selected, the regen level is very low. The motor is also limited to 63 Hp, and the Cruise Control lets the speed vary +- 5 miles per hour reducing peak battery drain. If the terrain does take a sharp dip the regen will increase to keep the car from running away (Grade Logic Regen), while allowing instant acceleration if needed, and Servo Brake reduces Friction to Regen ratio. Additionally, ECON reduces the A/C and Heater draw and lets temp vary more widely. Honda claims ~15% overall improvement. I was able to get 6.2mi/kWh from 17kWh available battery (105 miles) including a 4,000 foot climb/decent. Also works well over rolling terrain. Very efficient.
 
Caracalover said:
It would be great to have a no regeneration switch. With it on you gain no energy, with it off you then gain as much as the modes you are in allow.
I read about one EV with a control on the steering wheel to increase or decrease regen. I don't remember which car it was, but it sounds like exactly what I'd like.
 
I've long thought it would be ideal to have user-controllable regen via a "trim wheel", as is used on airplanes.

http://en.wikipedia.org/wiki/Trim_tab" onclick="window.open(this.href);return false;

Not only could this have a "zero regen" setting to satisfy the "neutral seekers" without having to drop out of gear, but it would also be helpful to maintain speed on a long descent by adjusting regen.
 
I agree with Josh. The most efficient way is to have no regen when the foot is off the gas(?) pedal.

Having regen only when braking should be an option.
 
I think I prefer the opposite - heavy regen on throttle-lift, and the brake pedal just adds hydraulic braking only. I believe I read that this is how the Model S implements it. I tend to always drive in ECO just to have more regen on throttle lift.

It would be nice if the throttle had some sort of "detent" when you hit the "neutral" position, so you could easily feel it instead of having to look at your gauges.
 
Nubo said:
I've long thought it would be ideal to have user-controllable regen via a "trim wheel", as is used on airplanes.

http://en.wikipedia.org/wiki/Trim_tab" onclick="window.open(this.href);return false;

Not only could this have a "zero regen" setting to satisfy the "neutral seekers" without having to drop out of gear, but it would also be helpful to maintain speed on a long descent by adjusting regen.


+1 wish someone would build one this way....perhaps an aftermarket adder.
 
is their any instrumentation that tells you when you go from regen braking to friction braking?

i would love to minimize the latter.
 
Caracalover said:
It sounds like you haven't looked at the power use screen, or even the bubbles in the dash that indicate power use. [...]

Thanks, I have watched the bubbles from day one and have been monitoring the power use screen extensively for the last 50-100 miles, as safety permits. I think you are simply misunderstanding the suggestion [edited: except in your previous post you did make the very useful suggestion of a simple switch to turn off regen, so this did seem to indicate understanding.]

Caracalover said:
When you lift your foot in either D or ECO you begin to regenerate power, rather than use it.

Exactly. I know this. I'd like an option where it is *not* the case that one begins to regenerate power, but instead goes into neutral.

Caracalover said:
By using ECO it is easier to let off a little to get to a no power use state than in D, but either mode is capable of this. In ECO the regeneration rate is higher than in D. The power use screen is the best way to see this.

Yes, thanks, I've done that (and mentioned so, perhaps in the other thread on highway efficiency?), but it is not possible to use these buttons or the power use screen and feathering the pedal to stay in *exact* neutral over longer distances (i.e.: to coast with optimimum efficiency). Hence, the suggestion of a new feature.

Caracalover said:
The Tesla has all the regen available on the power pedal. Many people never even have to use the brake, and it takes a little getting used to since the regen is so heavy. Not too sure about the others.

The point is to enable driver operation of the vehicle - if they want, in neutral, with zero power expenditure *or* regen, over as long a space as the driver chooses. I think this is something different than what you describe above, but I think it is something that could be accomplished with the use of your suggestion from another post of a switch to turn off regen.
 
thankyouOB said:
is their any instrumentation that tells you when you go from regen braking to friction braking?

i would love to minimize the latter.

Yes, I agree. This is a separate matter, but also in my view is a good idea.
 
KeiJidosha said:
jlsoaz said:
...Does anyone know if other EV manufacturers (Tesla? Honda?) offer a hassle-free energy-saving ability to coast in neutral and then go back to instant-on power as needed? Is this part of how Honda is able to attain excellent mpge? ...
The Honda Fit EV does not go to neutral, but in the ECON mode, with Drive selected, the regen level is very low. The motor is also limited to 63 Hp, and the Cruise Control lets the speed vary +- 5 miles per hour reducing peak battery drain. If the terrain does take a sharp dip the regen will increase to keep the car from running away (Grade Logic Regen), while allowing instant acceleration if needed, and Servo Brake reduces Friction to Regen ratio. Additionally, ECON reduces the A/C and Heater draw and lets temp vary more widely. Honda claims ~15% overall improvement. I was able to get 6.2mi/kWh from 17kWh available battery (105 miles) including a 4,000 foot climb/decent. Also works well over rolling terrain. Very efficient.

Thanks KeiJidosha, this is an answer I was looking for. A few thoughts upon reading this:

In considering this idea of whether sometimes it is more energy efficient to coast in neutral, I have sometimes thought back to when I was younger and used to ride a 12 speed road bike. Since our own bodies are providing energy, there is a visceral feel that one gest.... this doesn't mean we are right, and it is not comparable in all ways since the bike didn't have regen, but some thoughts:

- There are times when it seems best to coast and let the road do the work.
- If one were to have to maintain constant speed within one or two mph, and if one did not have the ability to see ahead and anticipate points where less or more power could be applied, then this would make for a harder bike ride. The Honda appears to be somewhat smarter than some other cars about trying to balance out cruise-control versus energy savings both by employing some flexibility about constant speed, and by trying to let the car "catch its breath" a little bit when encountering a grade.
- I don't recall as well the experience of riding a bike that would not go into neutral.

Anyway, when Honda (having noticeably resisted for years and years making any PEVs) was compelled (by the California ZEV mandate and/or competition, etc.) to make at least a compliance BEV, and has also I think announced coming out with a PHEV soon, they emphasized that they were able to apply lessons from their hydrogen vehicle program and thus attain very high efficiency. There was not only I think some face-saving in this but some corporate justification - I think Honda has probably spent some decent money on its H2 vehicle program and so it is natural to try to make arguments to show how it has paid off, if only in a side way. The Fit, even if a Compliance vehicle only, and even if under-equipped in battery pack kWh for many US drivers needing to cover longer intra-municipal distances, does seem to employ some smart energy saving methods that bespeak of some significant engineering effort on Honda's part. While the exact efficiency measures Honda uses are not exactly what I have suggested in this thread, and others have explored for years (using neutral judiciously to enhance range and efficiency), they are in the same vein of "all other things and kWh being equal, there is more that can be done to get better range".

From the standpoint of working with Nissan to help them prioritize Leaf improvements, I think we can use this a bit to help them understand that there is more to be done in the area of efficiency, and that their worthy competition has helped to point this up.
 
walterbays said:
Caracalover said:
It would be great to have a no regeneration switch. With it on you gain no energy, with it off you then gain as much as the modes you are in allow.
I read about one EV with a control on the steering wheel to increase or decrease regen. I don't remember which car it was, but it sounds like exactly what I'd like.

yes, and by bringing it to the steering wheel, it would be closer to some of the other suggestions made here.... sort of like a subtle cruise control or windshield wiper control, except instead of very good control over speed or windshield wiper frequency, one is controlling level of regen. Let's keep an eye out to discover which model this is, if it is out there.
 
mkjayakumar said:
I agree with Josh. The most efficient way is to have no regen when the foot is off the gas(?) pedal.

Having regen only when braking should be an option.

I think some of the drivers have demonstrated that there are efficiency gains to be had by avoiding regen, at least in some cases. I am not sure I would say that it's in all cases, but this just helps serve to emphasize that if we make it an easy and well-thought-out intuitive option (such as by trying some of the many suggestions here including a very simple switch, a steering-wheel regen control, some sort of airplane-like control (not sure I understand that one yet, but interesting), etc.) then perhaps Nissan could succeed in significantly improving range of the vehicle during normal operation for "average" drivers (not just in the hands of a skilled hyper-miler) and attain a higher EPA range and MPGE without altering the cost of the vehicle or the size of the battery.
 
I'll expand on a suggestion that I've seen on other message boards. I'd like to see a "neutral zone", aka. "coasting zone", on the accelerator pedal, with a slight, detectable "click" to let driver know when the pedal is entering/exiting this zone. A small amount of pedal travel would be allowed within this zone.

To illustrate, let's say the driver is pressing the accelerator pedal hard enough to apply power. As the driver releases pressure on the pedal, a slight click is felt, and the vehicle begins coasting, effectively in neutral. With further release of pressure, another click is felt, and the vehicle begins regenerative braking. Coasting would thus be easy but without the slight compromise in control of the vehicle inherent in having to "shift gears". Regenerative braking would remain available on the accelerator pedal, something I greatly favor.

Of course, not everyone will necessarily want this behavior, and I'd imagine it could be made configurable. Some engineering would be needed to incorporate tactile feedback in the accelerator pedal via "clicks".
 
garsh said:
I think I prefer the opposite - heavy regen on throttle-lift, and the brake pedal just adds hydraulic braking only. I believe I read that this is how the Model S implements it. I tend to always drive in ECO just to have more regen on throttle lift.

It would be nice if the throttle had some sort of "detent" when you hit the "neutral" position, so you could easily feel it instead of having to look at your gauges.

Hi Garsh:

side-note: I tried that "switch into neutral by switching to R" trick and it worked, but boy.... talk about having to re-wire my driving habits. Slightly scary the first time and since I've retained my stick-shift HCV for longer trips, I hope I don't get confused about which car I am driving (which has already happened a couple of times in non-damaging ways).

On the matter of preferences, I think that's what this is about - allowing drivers to choose. I like the suggestions for either a binary solution (such as an on-off switch for regen) or perhaps better a more graded solution (such as a steering wheel control for degree of regen).

I also think your suggestion here is worth discussing - for a simple solution of a better power pedal feel of a "detent" where one can know for sure that one is in neutral and keep it there, rather than having to watch the dashboard and guess imperfectly. However, when this suggestion was raised in the highway-efficiency discussion, there was some discussion of whether this would really be possible while maintaining a proper power pedal application. I don't know.

If one of the many suggestions was implemented, and done well, I don't think I would use it all the time, but in some cases I would do so (just as if I'm riding a bike and might myself want to coast for awhile to make optimal use of the energy I've expended to get to that speed, but to take a break from applying further energy). In other cases, I would imagine I'd try making good use of leaving it on regen. One reason for this might be if I am in a city situation with multiple stop-starts up ahead, and if I also want some bias toward slowing down for safety purposes (I can still hear my dad teaching me to drive and explaining that in general I should think about staying off the gas). Sure, coasting in neutral does not mean speeding up, but applying regen is a bit more biased toward slowing down regularly.
 
Back
Top