Cruise control and Eco mode?

[JasonT]

The Leaf that was driven down from Mission Viejo was in Eco for part of the drive, and it was said to me that in eco mode it does not go over 60mph.

This is totally not a "You're lying!" post. I just find this very hard to believe, as others here are. I know I've seen at least one (if not more) videos of Mark Perry talking through the demo of the Leaf and explaining that for the "go" pedal the only thing Eco mode does is increase resistance. I recall him specifically stating that they decided not to electronically modify the way acceleration works in eco mode -- that they want all power to be available to the driver. Now admittedly, acceleration is not the same as top speed, but I just... would be very surprised if they did this. I suspect (and hope) that someone was confused.

As for Eco mode on the Leaf, I don't know what it does, and apparently Nissan won't say.

Depends on what you mean by "Nissan". From videos and reviews we know specifically that Eco mode does the following things:

• Increased resistance on the Acceleration/Go/Gas pedal
• Increased regenerative braking
• Decreased climate control

The only surprise we have right now is this 60MPH limit.

Eco mode is silly and unnecessary.

Remember, the goal of the Leaf is to make this the car for "everyone". You are absolutely correct that someone can turn off/down climate control on their own, and they can watch their speed and acceleration on their own. The idea here is to give an easy option to help increase the range of the car. I don't see anything wrong with that. I will probably drive in eco mode all the time just because of the more aggressive regenerative braking. I realize that regen braking is not magic and that some basic hypermiling techniques would work just as well (if not better), but I've been driving a certain way for a very long time and I don't know how easily I can change my habits.

 

[mwalsh]

This whole ECO mode limited to 60mph deal might just be a factory imposition on the demo cars. I wouldn't worry about it being on our cars without a Nissan spokesperson saying it's going to be or the first batch of owners confirming it is in their *cough* blog *cough*.

 

[planet4ever]

... I keep thinking of eco mode as being like the "B" shift in a Prius, because both result in much heavier regen. ...

Very, very, very, very wrong!!!!! B mode in the Prius is engine braking. It may increase regen, but principally it uses engine compression to slow the car. This is a VERY INEFFICIENT way to drive, and should ONLY be used on long downhill runs where the battery becomes full and regen is no longer possible and the friction brakes would overheat. B mode dissipates energy as heat via the engine and throws it away, which is necessary on long downhills once the battery is full, but is wasteful under any other circumstances.

I'm sorry, daniel, but you are flat wrong. I have driven a Prius many times down a mountain pass on a winding road where the maximum safe speed was 35, down to 15 on the corners. I always use "B" mode, the regen is always heavy, and the engine is off until the battery gets full.

As for Eco mode on the Leaf, I don't know what it does, and apparently Nissan won't say. I gather from posts above that it gives less acceleration and reduces heating and A/C. But you can accomplish the same things in Drive mode: Step more gently on the go pedal to reduce acceleration, drive more slowly to reduce drag, set your heat lower and your A/C to a higher temp to conserve power. Then when you do need to accelerate hard, or speed up, you can do so.

It seems to me that Nissan (through Mark Perry) has been quite specific. Eco mode does increase regen and it does not reduce possible acceleration. It only changes the pedal feel so that you have to push harder to get maximum acceleration. It may be possible to get the same level of regen by riding the brake; that I don't know.

I say that c/c and Eco mode is a non-issue because Eco mode is silly and unnecessary.

Perhaps unnecessary (depending on regen level with the brake pedal) but hardly silly.

What's of more interest to me is whether the Leaf has any provision to dissipate energy on long downhills if the battery is full or if it's too steep for regen to absorb all the energy, in order to avoid overheating the brake pads. Maybe they figure the size of the battery renders that moot. But it's a technical detail that would be interesting, if Nissan was not refusing to tell us much of anything about the car.

The answer is: Definitely moot, and there are other things I'd much rather hear about -- such as the interaction between eco and cruise control.

 

[DaveEV]

I'm sorry, daniel, but you are flat wrong. I have driven a Prius many times down a mountain pass on a winding road where the maximum safe speed was 35, down to 15 on the corners. I always use "B" mode, the regen is always heavy, and the engine is off until the battery gets full.

Weird - my car works the same as Daniel's. As soon as you turn on B mode the engine starts spinning whenever you take your foot off the gas to slow the car down.

 

[palmermd]

So, one cannot use the "eco" heater or A/C modes at freeway speeds?

Its not really eco if you are going down the freeway at 80mph. I imagine they chose to disable eco at speeds above 60, because anytime you are going that fast you are more concerned about saving yourself time they you are about being eco.

 

[LEAFguy]

What's of more interest to me is whether the Leaf has any provision to dissipate energy on long downhills if the battery is full or if it's too steep for regen to absorb all the energy, in order to avoid overheating the brake pads.

Just curious... what modern era vehicles do you have experience with that overheat the brake pads in everyday driving? If the vehicle is not overloaded, I have not seen this as an issue.

 

[daniel]

I'm sorry, daniel, but you are flat wrong. I have driven a Prius many times down a mountain pass on a winding road where the maximum safe speed was 35, down to 15 on the corners. I always use "B" mode, the regen is always heavy, and the engine is off until the battery gets full.

Weird - my car works the same as Daniel's. As soon as you turn on B mode the engine starts spinning whenever you take your foot off the gas to slow the car down.

Thank you, drees. BTW I have been driving my Prius since 2004, though I seldom drive it since I got the EV about three years ago.

What's of more interest to me is whether the Leaf has any provision to dissipate energy on long downhills if the battery is full or if it's too steep for regen to absorb all the energy, in order to avoid overheating the brake pads.

Just curious... what modern era vehicles do you have experience with that overheat the brake pads in everyday driving? If the vehicle is not overloaded, I have not seen this as an issue.

Not in everyday driving, but when driving very long, steep downhills, typically coming down a mountain. In a conventional car you shift to a lower gear so the engine will slow you down. In a Prius, B mode uses the engine to slow you down. But a plain-jane EV has no means to slow the car other than the brake pads if the battery is too full for regen, or if regen alone is not sufficient.

BTW, regen should never be on the go pedal. Regen should be on the brake pedal. It is inefficient to have to car apply regen whenever you take your foot off the go pedal. Regen should only be applied when you ask the car to slow down by stepping on the accelerator pedal.

 

[EVDRIVER]

I'm sorry, daniel, but you are flat wrong. I have driven a Prius many times down a mountain pass on a winding road where the maximum safe speed was 35, down to 15 on the corners. I always use "B" mode, the regen is always heavy, and the engine is off until the battery gets full.

Weird - my car works the same as Daniel's. As soon as you turn on B mode the engine starts spinning whenever you take your foot off the gas to slow the car down.

Thank you, drees. BTW I have been driving my Prius since 2004, though I seldom drive it since I got the EV about three years ago.

What's of more interest to me is whether the Leaf has any provision to dissipate energy on long downhills if the battery is full or if it's too steep for regen to absorb all the energy, in order to avoid overheating the brake pads.

Just curious... what modern era vehicles do you have experience with that overheat the brake pads in everyday driving? If the vehicle is not overloaded, I have not seen this as an issue.

Not in everyday driving, but when driving very long, steep downhills, typically coming down a mountain. In a conventional car you shift to a lower gear so the engine will slow you down. In a Prius, B mode uses the engine to slow you down. But a plain-jane EV has no means to slow the car other than the brake pads if the battery is too full for regen, or if regen alone is not sufficient.

BTW, regen should never be on the go pedal. Regen should be on the brake pedal. It is inefficient to have to car apply regen whenever you take your foot off the go pedal. Regen should only be applied when you ask the car to slow down by stepping on the accelerator pedal.

No offense but I have been driving EVs for years and to say regen on the "go' pedal is less efficient is flat out wrong, in fact it can be MORE efficient under many conditions but is never less efficient. What is your EV driving experience, what types of drive systems have you used?

 

[DaveEV]

No offense but I have been driving EVs for years and to say regen on the "go' pedal is less efficient is flat out wrong, in fact it can be MORE efficient under many conditions but is never less efficient. What is your EV driving experience, what types of drive systems have you used?

When regen is engaged automatically when you take your foot of the go pedal that forces you to feather the go pedal when what you really want to do is coast.

See pulse-and-glide technique on the Prius - it takes a lot of practice to glide on the Prius and even with practice it is not easy for all to glide.

Now granted on an EV glide is much less important for maximum efficiency, but there are plenty of times when you'd want to coast as fast as possible (such as down slight hills) without having to worry if you are slightly in regen or on the "go".

 

[Long4Leaf]

Forgive me, but I am not an EV guy, I have never driven one in my life. Nor a hybrid for that matter. So being one of the millions of target customers for Nissan, I would like the car to slow down when I take my foot off the gas, just like what I am used to with ICE.

 

[LEAFer]

We had this whole regen/go-pedal/brake-pedal/coasting trade-off discussion in another thread a while back. Let's leave it there, or add to it, but not here :roll:

 

[evnow]

No offense but I have been driving EVs for years and to say regen on the "go' pedal is less efficient is flat out wrong, in fact it can be MORE efficient under many conditions but is never less efficient. What is your EV driving experience, what types of drive systems have you used?

We have been through this before - a lot. It is just basic physics. Since the round trip to the battery is not 100% efficient, it is better to coast than regen and then accelerate using that regen energy.

The other way to coast, ofcourse, is to use cruise control.

 

[EVDRIVER]

No offense but I have been driving EVs for years and to say regen on the "go' pedal is less efficient is flat out wrong, in fact it can be MORE efficient under many conditions but is never less efficient. What is your EV driving experience, what types of drive systems have you used?

We have been through this before - a lot. It is just basic physics. Since the round trip to the battery is not 100% efficient, it is better to coast than regen and then accelerate using that regen energy.

The other way to coast, ofcourse, is to use cruise control.

Cruis control is inefficient because it over compensates. Coasting is not more efficient it is subjective to driving conditions. What many people do not understand is that if you stop short, have steep hills or drive briskly which can result in quicker stops pedal regen ALLOWS for higher levels than brake only presently and will recapture more energy. This has been proven and the results are clear. To say coasting is more efficient is not accurate. Yes it is better to avoid recapturing energy rather tan conserving but that is not the reality of all driving styles and conditions. And please note the Leaf has less regen on the brake in comparison to other vehicles with the same setup to make it "feel safe" for those type of customers. Much energy will go to the brake pads. I would be glad to debate these points with anyone with decent driving experience on both types of setups.

 

[planet4ever]

I'm sorry, daniel, but you are flat wrong. I have driven a Prius many times down a mountain pass on a winding road where the maximum safe speed was 35, down to 15 on the corners. I always use "B" mode, the regen is always heavy, and the engine is off until the battery gets full.

Weird - my car works the same as Daniel's. As soon as you turn on B mode the engine starts spinning whenever you take your foot off the gas to slow the car down.

Perhaps we are talking about different speeds. I was careful to say I was traveling not more than 35 MPH. As many people know, the Prius ICE has to be running when the vehicle is at a high speed.

Are you guys saying that if you go downhill in "B" mode you don't see "regen cars" being built in the display bars or the battery charge level going up? I certainly do. And there is an obvious change when the battery does fill up - the engine revs up and produces a very loud whine.

 

[evnow]

To say coasting is more efficient is not accurate. Yes it is better to avoid recapturing energy rather tan conserving but that is not the reality of all driving styles and conditions.

We all get the second point. The first one is what people talk about in an ideal situation i.e. they are just making a basic physics point. .... both are correct.

 

[daniel]

Forgive me, but I am not an EV guy, I have never driven one in my life. Nor a hybrid for that matter. So being one of the millions of target customers for Nissan, I would like the car to slow down when I take my foot off the gas, just like what I am used to with ICE.

Even if it wastes energy?

No offense but I have been driving EVs for years and to say regen on the "go' pedal is less efficient is flat out wrong, in fact it can be MORE efficient under many conditions but is never less efficient. What is your EV driving experience, what types of drive systems have you used?

We have been through this before - a lot. It is just basic physics. Since the round trip to the battery is not 100% efficient, it is better to coast than regen and then accelerate using that regen energy.

The other way to coast, ofcourse, is to use cruise control.

Cruis control is inefficient because it over compensates. Coasting is not more efficient it is subjective to driving conditions. What many people do not understand is that if you stop short, have steep hills or drive briskly which can result in quicker stops pedal regen ALLOWS for higher levels than brake only presently and will recapture more energy. This has been proven and the results are clear. To say coasting is more efficient is not accurate. Yes it is better to avoid recapturing energy rather tan conserving but that is not the reality of all driving styles and conditions. And please note the Leaf has less regen on the brake in comparison to other vehicles with the same setup to make it "feel safe" for those type of customers. Much energy will go to the brake pads. I would be glad to debate these points with anyone with decent driving experience on both types of setups.

No offense but I have been driving EVs for years and to say regen on the "go' pedal is less efficient is flat out wrong, in fact it can be MORE efficient under many conditions but is never less efficient. What is your EV driving experience, what types of drive systems have you used?

When regen is engaged automatically when you take your foot of the go pedal that forces you to feather the go pedal when what you really want to do is coast.

See pulse-and-glide technique on the Prius - it takes a lot of practice to glide on the Prius and even with practice it is not easy for all to glide.

Now granted on an EV glide is much less important for maximum efficiency, but there are plenty of times when you'd want to coast as fast as possible (such as down slight hills) without having to worry if you are slightly in regen or on the "go".

This is exactly the point! With regen on the go pedal it is more difficult to coast when that is what you want to do, since you have to find exactly the right spot. On the Prius this is difficult to do. When the go pedal is just for going, and the brake pedal is for slowing or stopping, it is much easier for the driver to decide which to do.

And if the Leaf always uses the brake pads, even when regen would be adequate for slowing down, then it is wasting energy every time you slow down. The Prius does the brake pedal correctly: Braking is always 100% regen until regen would not be sufficient (very low speed or hard pressure on the brake pedal).

My two EVs lack regen, and taking my foot off of both pedals allows them to coast, which is much more comfortable than trying to coast in the Prius.

 

[EVDRIVER]

Adjustable regen solves all these issues perfectly. It provides the best of both worlds and user choice to match the best situation at the time.

 

[garygid]

Without variable, but substantial Regen on the brake pedal, I will probably not buy the LEAF.

Also, I will use the minimum "foot-off" Regen (I prefer zero), and "require" a way to no-drag coast (or very close).

Yes, easily adjustable foot-off Regen helps match many situations and preferences, and it should just be a relatively simple, essentially-no-cost firmware feature.

It should be easy to add/modify in a software update.

 

[planet4ever]

It should be easy to add/modify in a software update.

In fact they've already done it. The LEAF starts out in minimum foot-off regen mode. If you click the shifter to "D" a second time it switches to heavier foot-off regen.

You can drive Eco-off and be happy. I can drive Eco-on and be happy. Problem solved.