Honva
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B mode vs e-padel efficiency

Mon Mar 26, 2018 7:37 am

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.

Br4hm4
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Re: B mode vs e-padel efficiency

Mon Mar 26, 2018 8:49 am

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.

Honva
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Re: B mode vs e-padel efficiency

Thu Mar 29, 2018 7:25 pm

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.

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IssacZachary
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Re: B mode vs e-padel efficiency

Thu Mar 29, 2018 9:01 pm

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.
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Honva
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Re: B mode vs e-padel efficiency

Fri Mar 30, 2018 7:10 am

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.

jjeff
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Re: B mode vs e-padel efficiency

Fri Mar 30, 2018 12:40 pm

Honva wrote: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 :(
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Re: B mode vs e-padel efficiency

Fri Mar 30, 2018 1:42 pm

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.
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jonathanfields4ever
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Re: B mode vs e-padel efficiency

Sat Mar 31, 2018 3:35 am

Honva wrote: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.

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IssacZachary
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Re: B mode vs e-padel efficiency

Sun Apr 01, 2018 8:54 pm

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.
Last edited by IssacZachary on Sun Apr 01, 2018 8:58 pm, edited 2 times in total.
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IssacZachary
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Re: B mode vs e-padel efficiency

Sun Apr 01, 2018 8:56 pm

jonathanfields4ever wrote: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.
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