Putting the LEAF in "N"

[gbarry42]

Drop into ECO for a minute to capture regen (and slow down), then back to N for coasting. No touching the brakes, no wasted energy!

Regen is not a 100%-return proposition. It is certainly more efficient than using the friction brakes, but it can't beat coasting. What most people don't realize, though, is that light application of the brake does the same thing as the regen you see in ECO.

 

[Jimmydreams]

Drop into ECO for a minute to capture regen (and slow down), then back to N for coasting. No touching the brakes, no wasted energy!

Regen is not a 100%-return proposition. It is certainly more efficient than using the friction brakes, but it can't beat coasting. What most people don't realize, though, is that light application of the brake does the same thing as the regen you see in ECO.

You lost me. "not a 100% return proposition"? What does that mean? If you're referring to regen being inefficient, you're right, but using regen to grab some power vs brakes to slow down is better. Gaining power over creating wasted heat always wins!!

If you're in N, you get zero regen out of the brakes, at least according to the dots....I'd have to look at the energy use screen.

What I do is coast down a hill in N, and if I need to scrub off a little bit of speed, I go to D then ECO real quick for maximum regen and speed reduction. Once my speed is back where I want it, I go right back to N, never touching the brake. Simple and easy.

 

[gbarry42]

I was referring to the inefficient part. You are right, and I am right, and the problem is we are speaking in different contexts. I don't coast in N so I wasn't thinking in those terms. You do, so you have different options. Friction brakes are always the worst choice--but the problem is we may not be able to tell when they come in--and as I say, this is yet another story.

 

[Caracalover]

I have no argument with that. The issue arises when coasting causes you to accelerate above your normal driving speed. That is when I say there is an unknown (at least to me) tradeoff between regen losses and high speed air resistance losses.

Ray

If you get too high over your target speed, use regen in D or Eco to slow the car, no sense getting up more speed than you are comfortable with. Few hills are long enough and steep enough to achieve truly high speeds where wind resistance will be a major factor. I have the luxury of a short commute, so I go at high speeds, flowing with traffic or even passing it. Love the acceleration in this car, and I don't want non-electric car drivers to think the LEaf is slow, I assure you that when they see mine, they don't. Having said that I also enjoy playing with the slow speed city driving when no one is around, and I seek ways to work with no one around. My average speed (Car menu) is 19.9 mph which is crazy slow for the way I drive, have to wonder if that is accurate. I will have to start driving the freeway more, but with so many cars and so many distracted drivers, I hesitate to put a car that I can't replace easily in harms way.
Best, Eric

 

[DaveEV]

Drop into ECO for a minute to capture regen (and slow down), then back to N for coasting. No touching the brakes, no wasted energy!

Regen is not a 100%-return proposition. It is certainly more efficient than using the friction brakes, but it can't beat coasting. What most people don't realize, though, is that light application of the brake does the same thing as the regen you see in ECO.

You have to remember that coasting at higher speed is like driving with the brake on both act as friction slowing the car down!

As planet4ever said - at some point using regen to maintain speed going down a hill is quite likely to be more efficient than coasting.

For example - assume that it takes 15 kW (250 Wh/mile) to maintain 60 mph on flat ground and 21 kw (300 Wh/mile) to maintain 70 mph. Now assume that your desired minimum speed is 60 mph your maximum speed is 70 mph, your goal is to maximize efficiency and you are headed down a hill where when coasting your terminal velocity is 70 mph. This indicates that you should be able to regen at 6 kW and still maintain 60 mph.

Assuming that the hill is 1 mile long, 6 kW at 60 mph will take a minute - so you'll capture 100 Wh - or enough energy to travel 0.4 miles at 60 mph on flat ground. The question is: How far do you travel while coasting down to 60 mph from 70 mph once you reach flat ground? Is it more or less than 0.4 miles? If it's more then you're better off coasting. If it's less then you're better off using some regen down the hill.

PS - someone check my math - the power requirements should be fairly representative for the LEAF in the real world.

 

[SparkyEV]

What I do is coast down a hill in N, and if I need to scrub off a little bit of speed, I go to D then ECO real quick for maximum regen and speed reduction. Once my speed is back where I want it, I go right back to N, never touching the brake. Simple and easy.

I do the same thing, but I stay in ECO the whole time and just use the pedal to smoothly transition between coasting & regen. It seems easier & quicker to me to do it all with a single control. I only use regen if I need to slow down due to conditions. I try to build up as much speed as possible (and practical) on downhills and coast (feather the pedal for zero power, no regen) as far as I can until my speed bleeds off.

 

[Caracalover]

when you put the shifter into neutral , What do they read?

You will see an "N" where the D or ECO would be, and no power is used or regained. switch back to D or ECO to speed up or slow down, using the brake as a last resort.

 

[mwalsh]

when you put the shifter into neutral , What do they read?

You will see an "N" where the D or ECO would be, and no power is used or regained. switch back to D or ECO to speed up or slow down, using the brake as a last resort.

Don't get sucked in by the SPAM, my friend!

 

[EVDRIVER]

Folks, please do not respond or comment on spam, it creates more clutter and posts for moderators to delete. I delete all the spam I see but there is no point in adding multiple replies to dirty up the threads.

Thanks!

 

[brettcgb]

I noticed a slightly delay when putting in Neutral, I wondered why did they feel the need for this...

My guess is this to support on-the-fly changing between D and ECO, since you must pass through N to get to D / ECO.

I think a delay going to neutral is something like asking "Are you sure you want to shift to neutral?" You have to want to go to N rather than pass through N.

(Shifting between E and D doesn't really go through N.)

 

[harryjpowell]

Can't some smart EE find a way for us to wire in a switch to turn off regen braking? This way we could use cruise control and let the car coast above speed on downhills and be as efficient as we want?

 

[garsh]

Can't some smart EE find a way for us to wire in a switch to turn off regen braking? This way we could use cruise control and let the car coast above speed on downhills and be as efficient as we want?

I just push the shifter into reverse (which engages neutral without the delay) whenever I want to coast.

When the car returns to cruise speed, I push the accelerator down slightly (to prevent regen braking for the next step), shift back to "D" and hit "resume" on the cruise control. That part takes a little coordination, but it's not too bad.

 

[EZ2BGRN]

I (accidentally) tried putting my car into R as I was driving (forward). Nothing happened - it stayed in D (or ECO).

 

[DaveinOlyWA]

I (accidentally) tried putting my car into R as I was driving (forward). Nothing happened - it stayed in D (or ECO).

you did not engage hard enough? i guess. i use this method exclusively and it works fine for me. you should hear a beep when it kicks to neutral but i also prefer this method because there is no delay shifting to neutral. it is very quick

 

[LEAFfan]

I (accidentally) tried putting my car into R as I was driving (forward). Nothing happened - it stayed in D (or ECO).

you did not engage hard enough? i guess. i use this method exclusively and it works fine for me. you should hear a beep when it kicks to neutral but i also prefer this method because there is no delay shifting to neutral. it is very quick

+1! I just flick the knob into 'R' and it works every time at 7mph and over.

 

[nerys]

well fear no more I am your test subject. I accidentally hit the PARK button while driving and almost freaked. then nothing happened. thankfully the system was designed smart enough to realize that would be bad to execute such a command