jlsoaz
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Drive option that better incorporates neutral/coasting

Tue Jan 01, 2013 12:40 pm

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.
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garsh
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Re: Drive option that better incorporates neutral/coasting

Tue Jan 01, 2013 3:56 pm

jlsoaz wrote: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.
:)
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Caracalover
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Re: Drive option that better incorporates neutral/coasting

Tue Jan 01, 2013 4:31 pm

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%.
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garygid
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Re: Drive option that better incorporates neutral/coasting

Tue Jan 01, 2013 8:02 pm

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.
See SOC/GID-Meter and CAN-Do Info
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jlsoaz
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Re: Drive option that better incorporates neutral/coasting

Thu Jan 03, 2013 10:10 am

garygid wrote: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.
Former lessee 2012 SL
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2017-October: bght 2013 Volt
will buy 150+ mile BEV when they become less expensive on used market
opinions expressed are my own

Caracalover
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Re: Drive option that better incorporates neutral/coasting

Thu Jan 03, 2013 8:34 pm

jlsoaz wrote: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.
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KeiJidosha
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Re: Drive option that better incorporates neutral/coasting

Thu Jan 03, 2013 11:23 pm

jlsoaz wrote:...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.
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walterbays
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Re: Drive option that better incorporates neutral/coasting

Thu Jan 03, 2013 11:28 pm

Caracalover wrote: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.

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Nubo
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Re: Drive option that better incorporates neutral/coasting

Fri Jan 04, 2013 1:32 am

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 noticed you're still working with polymers.

mkjayakumar
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Re: Drive option that better incorporates neutral/coasting

Fri Jan 04, 2013 3:44 am

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.
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