B mode vs e-padel efficiency

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Honva

Member
Joined
Mar 26, 2018
Messages
23
Location
Ontario, Canada
Just got my 2018 Leaf a few days ago. So far like it very much. Very quiet and responsive.
Just wondering if anyone did tests to see if B mode save more energy or e-padel mode save more energy. (could be different while on highway vs city).
It is not clear from Nissan's description when and how much friction brake it uses in e-padel mode. On the other hand, in B mode, friction brake is not applied at all if you don't press the brake padel.
 
In my experience, they are about the same. I do notice a little bit of difference highway driving, seems to be better in B mode, but I don't have hard data at this point.
 
I did some comparison tests in the last few days. Driving to work and back home. I alternate one day e-pedal and one day B mode. I am suprised to find that B mode actually slightly more efficient. Both the kwh/100km number and regeneration km are better. This lead me to believe my suspicion that the stronger deceleration in e-pedal mode is due to the computer applying slight friction brake for us automatically rarher than stronger regeneration.
 
Whatever gives the least amount of regenerative braking is going to be more efficient, provided you started slowing down sooner.

The most efficient mode is shifting into neutral and coasting down to a slower speed miles ahead of time.

Regular "D" non-eco, non-B, non-E-pedal mode is more efficient if you also start slowing down way ahead of time.

Eco, B mode and E pedal are less efficient. The more regenerative braking you have, even without any added friction braking, will be less efficient.
 
It is only true "if" you are the only one on the road. In city driving reality, one needs a way to reduce speed faster than cruising down. Re-gen is more efficient than friction brake.
 
Honva said:
It is only true "if" you are the only one on the road. In city driving reality, one needs a way to reduce speed faster than cruising down. Re-gen is more efficient than friction brake.
+1
Whenever I hear someone say it's better to coast than use regen.....well they apparently don't live in a city.....or at least mine :lol:
Where if you leave more than a car length between yourself and the person in front of you, it will have someone cutting into it within seconds :x Without regen I'm basically forced to go from gas to brake, with B mode engaged I'm able to not push the break as often, which helps with regen.
Sure if I lived in the country I might be able to use some free coasting but in the city the only time I'm really able to coast is getting off the freeway and even then if I start slowing down too soon before the exit, the guy behind me will quickly pass me up and then cut back in front of me, resulting in me having to push the brake pedal even harder :(
 
As usual, the truth lies between the extremes. I tell people that B mode is best for stop and go (or stop and slow) driving, while D or D-Eco is best for the highway. That allows more coasting than B mode, and so is more efficient without requiring any shifting to N. The little bit of coasting you get in D increases the overall efficiency. Leaf Box is supposed to let you do real coasting in D, which sounds nice.
 
Honva said:
I did some comparison tests in the last few days. Driving to work and back home. I alternate one day e-pedal and one day B mode. I am suprised to find that B mode actually slightly more efficient. Both the kwh/100km number and regeneration km are better. This lead me to believe my suspicion that the stronger deceleration in e-pedal mode is due to the computer applying slight friction brake for us automatically rarher than stronger regeneration.

I hope that’s not true. I’ve gotten so used to e-Pedal that it would really be a shame if it was blending more than we thought. I was under the impression that it only applies the friction brakes at very low speeds where regen won’t work.
 
I wasn't saying you should shift into neutral every time you want to decelerate. I don't live in the city and I do try to hypermile as I try to make it 70 miles between charging stations in my 11 bar 2013 Leaf over steep, winter blasted mountain passes and I, even I still do not come coasting to a stop in neutral ever.

Coasting to a stop is hypothetical just like using up all your momentum with friction braking is hypothetical (unless you slam into a concrete wall). Hypothetically, friction braking is 0% efficient. Hypothetically, regenerative braking is around 40% efficient on average. Hypothetically, coasting is 100% efficient.

Any time you're slowing down you are coasting or partially coasting, that is, using momentum to keep moving the vehicle forward. If half the energy stored in the vehicle's momentum is used to move the car forward (coasting) and half is used for regenerative braking at 40% efficiency you still end up with 70% back (50% moving the car forward and 20% for starting the car again) from the energy you spent originally to speed up the car in the first place. But if 75% is regenerative braking them you only get 55% back. If it's 90% then you only get 46% back. Etc. Or perhaps even less since the more current you push into the battery the less efficient it is, so your 40% efficiency could drop to 30% or even 25%. Now you're only getting back 35% total from decelerating abruptly instead of taking your time and slowly regenerating and making that 70% you could have.

Therefore the most efficient braking is to use the least amount POSSIBLE of regenerative braking WITHOUT having to use any friction braking. If in your circumstances that means using the e-pedal, then the e-pedal is most efficient. But if you can do this in B mode then B more is going to be the most efficient for your circumstances. If you can do it in ECO mode, well then even better. And if you can pull this off in plain old D mode, well you've pretty much hit the jackpot.

Then one day after the Apocalypse you find you're the only survivor in the world and your Leaf is the last car running and you have all the roads in the world to yourself and desperately need to use as little energy as possible to make it from working charging station to working charging station... Then go ahead and try to coast to stops. But don't just slam it into as much regen as possible just because there's one other car on the road if you're trying to be efficient to a reasonable degree.
 
jonathanfields4ever said:
I was under the impression that it only applies the friction brakes at very low speeds where regen won’t work.
I understand that E-Pedal applies the friction brakes any time regen is limited, like when you've charged to 100% or when the battery is cold.
 
Found this page from Nissan with more details on how e-pedal function.

https://www.nissan-global.com/EN/TECHNOLOGY/OVERVIEW/e_Pedal.html

From the description, it appears that friction brake is not normally used until stop. Only engaged on slippery road.

It should have as good efficiency if not better. I am going to try more comparison test with more careful driving on b vs e-pedal.
 
Ok, did more driving in e-pedal mode and here is my observation.

e-Pedal mode could be as efficient as B mode, if not more. What I observed is that e-Pedal do not apply the brakes if you don't let go the accelerator completely. Even, if you just leave the accelerator very slightly from complete release, the car will keep rolling until the last bit of momentum is consumed. When you car is very slow, it is like putting it in neutral. If you let go completely, brakes will engage.

So, if you want to gain efficiency, try moderate the speed with reduced pedal rather than let go completely. Only let go completely when the car almost fully stop to engage the brake to hold it. The manual although not explaining the details, also suggested not to let go completely but to moderate the pedal position. I have been able to get ~13Kwh/100km in bad stop and go city traffic in e-Pedal mode. Not bad at all.

I found that the major advantage of e-Pedal over B mode in traffic is that I could rest my foot instead of holding the brake pedal when stopped. Also, there is a convenience that when you put the car in gear, you do not need to do it twice to get to B mode. In e-Pedal mode, there is no difference between D and B.

Eco mode does not really save traction motor energy. It just give you a different response curve for the pedal range to promote slower acceleration. You can get the same slower acceleration with less foot movement. One area Eco mode save energy is that it seems to made the car use less of the resistive heater when you first start from cold. It will shut off the resistive heater earlier and relies more on the heat pump. Yes, it will take a little bit longer to warm up but you save a bit of power. When it is cold, I do now start the car in Eco mode and switch it off after it warms up a bit.
 
Honva said:
Eco mode does not really save traction motor energy. It just give you a different response curve for the pedal range to promote slower acceleration. You can get the same slower acceleration with less foot movement.
Sorry, I have to disagree.

Anytime you use regenerative braking you are turning momentum energy into electric energy AND heat energy. That's a loss of energy, an inefficiency, because nothing is 100% efficient. And the more regenerative braking you use the more energy you lose and the less efficient it is.

Try speeding up to 60mph/100kph and then slowing back down to half that many many times in B mode or E-Pedal mode and then try the same thing in D mode without ECO and then try it coasting in neutral and see which gives you the best miles/km per kWh.
 
IssacZachary said:
Sorry, I have to disagree.

Anytime you use regenerative braking you are turning momentum energy into electric energy AND heat energy. That's a loss of energy, an inefficiency, because nothing is 100% efficient. And the more regenerative braking you use the more energy you lose and the less efficient it is.

Try speeding up to 60mph/100kph and then slowing back down to half that many many times in B mode or E-Pedal mode and then try the same thing in D mode without ECO and then try it coasting in neutral and see which gives you the best miles/km per kWh.

Unfortunately, not everyone lives in the desert where your car is the only moving object. Try the experiment you suggested in the city and the only two places you end up are either the hospital or police station. :D (Ah...I may be wrong! Could be in the morgue too). It is no different to say if we live in outer space, once I set in motion in the right direction, I can even turn the car off and go far far away!
 
Honva said:
Unfortunately, not everyone lives in the desert where your car is the only moving object. Try the experiment you suggested in the city and the only two places you end up are either the hospital or police station. :D (Ah...I may be wrong! Could be in the morgue too). It is no different to say if we live in outer space, once I set in motion in the right direction, I can even turn the car off and go far far away!
Well, if your only choice is to slam on the brakes, what's the point in asking about efficiency? Just keep slamming on them and be happy.

But for me, I know there's usually a happy medium between using as much inefficient regen braking as possible and letting the momentum bleed off efficiently. And I'm going to use that as best as I can within a reasonable limit to increase my efficiency.

This conversation is like pointing out that going slower, down to 12mph, is more efficient than driving faster and someone saying that since they live in the city and it is not possible to drive 12mph that their only choice is to drive around at 100mph.
 
I guess you may have read the title of this thread wrong. This thread is about "B mode vs e-pedal efficiency", not "which mode is the most efficient" or "how people should drive". D mode is off topic.

Each mode has its benefit and the driver will choose based on the traffic condition. This is why Nissan include different modes in the car.
 
Honva said:
I guess you may have read the title of this thread wrong. This thread is about "B mode vs e-pedal efficiency", not "which mode is the most efficient" or "how people should drive". D mode is off topic.

Each mode has its benefit and the driver will choose based on the traffic condition. This is why Nissan include different modes in the car.
So the answer is NEITHER! Are you happy to know the answer?

If one provides less regen without causing you to need to use friction braking then theoretically it's more efficient. But then again it looks like they're practically the same. If there's a difference we're splitting hairs here. Both are inefficient and there's nothing you can do about it.

Sorry if it is too hard to comprehend how pointing out relevant comparisons with how other modes affect efficiency can help us all understand whether the e-pedal or the B mode could be more efficient than the other.

I'm not telling anyone how to drive nor what mode they should use. I am making a comparison. A comparison. Do you need to know the definition of a comparison? It's a way of illustrating a point. What's the point I'm making? That B mode could be a slightly more efficient than e-pedal. How do we know this? Through comparisons with other levels of regenerative braking!

There's no need to twist everything I say into that I'm some sort of city hating redneck that's using this thread to promote driving like an idiot when all I'm simply trying to do is illustrate the correct answer!
 
Hi everyone, looking into this old thread because I'm ordering a Leaf now. Just want to thank OP Honva for your testing.

IssacZachary you make good hypothetical points, but I think that one thing we should keep constant in this efficiency test is stopping distance, which in the case of most drivers, should be set at an acceptable city traffic distance. I think with OP's testing, e-pedal can achieve same or better B-mode efficiency with proper pedal throttling.

For highway driving, since you may have possibly infinite stopping distance, I agree with you. D is probably better. It looks like with e-pedal you can achieve D or even N level coasting with proper throttling to not activate the regen brakes, but nobody wants to hold it at a spot like that, so it would be better to go into D or N.
 
rchsun said:
Hi everyone, looking into this old thread because I'm ordering a Leaf now. Just want to thank OP Honva for your testing.

IssacZachary you make good hypothetical points, but I think that one thing we should keep constant in this efficiency test is stopping distance, which in the case of most drivers, should be set at an acceptable city traffic distance. I think with OP's testing, e-pedal can achieve same or better B-mode efficiency with proper pedal throttling.

For highway driving, since you may have possibly infinite stopping distance, I agree with you. D is probably better. It looks like with e-pedal you can achieve D or even N level coasting with proper throttling to not activate the regen brakes, but nobody wants to hold it at a spot like that, so it would be better to go into D or N.

Yes. That's basically the point.

Stop as quickly as necessary, but no need to stop quicker.

I'm not sure which regen brakes more, e-pedal or B-mode, but yes, you can always "throttle" the regen.

The point about coasting to a stop isn't meant to mean that that's what you're supposed to do. It only illustrates the point that the less you brake, even regen brake, the more energy is conserved. It's like mentioning that 12mph is the most efficient speed to drive at. That doesn't mean everyone should drive at 12mph, but the closer you can drive to that speed, say 65mph instead of 70mph, the more efficient your driving will be.
 
I have done quite a bit of driving recently to test differing driving configurations:

B Mode - Eco Mode - e-Pedal - 1 Week
B Mode - Eco Mode - No e-Pedal - 1 Week
B Mode - No Eco Mode - No e-Pedal - 1 Week
B Mode - No Eco - e-Pedal - 1 Week
D Mode - Eco Mode - e-Pedal - 1 Week
D Mode - Eco Mode - No e-Pedal - 1 Week
D Mode - No Eco Mode - No e-Pedal - 1 Week
D Mode - No Eco - e-Pedal - 1 Week

For my test purposes only, I drive 19.5 miles each way to and from work. Of the 19.5 miles, approximately 2 of them are city streets, the rest is highway. Now, in my city, highway can be almost full speed the whole way one day and stop and go the next (people cannot drive here for nothing!) Here are my conclusions on my driving habits:

1) B-Mode with Eco on and e-Pedal off is the most efficient.
2) Not using the Propilot Assist is the most efficient.

1a) Switching on the e-Pedal as I am exiting the highway improved efficiency
2a) The problem with the Propilot Assist is that once traffic in front clear, it will floor the accelerator to catch up and slams on breaking to slow down as traffic does. Not using Propilot Assist, I am able to gradually increase speed when traffic clears and can anticipate slowdowns ahead keeping off the friction braking completely.

Just my 2 cents and wanted to share for anyone who may have a similar drive.

Cheers,
Eryk
 
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