D mode is better than B mode? What gives?

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tkdbrusco

Well-known member
Joined
Sep 7, 2014
Messages
510
So I've started to drive my MY15 in D mode more frequently than B mode. I was always under the impression that B+Eco was the best for range and efficiency, but it seems like that's not the case.

My average efficiency in B+Eco was 4.7mi/kwh and my average efficiency in D+Eco was 4.9mi/kwh. I've been driving a nearly identical commute in D+Eco for 1000 miles, so I would assume that these numbers are pretty accurate and would indicate roughly a 4% benefit overall? My GOM readings have also improved, not that this is any real measure.

Here's what I'm thinking, D mode doesn't decelerate as aggressively and thus allows you to coast further. If you feather the throttle, you can actually coast in D mode with one green dot showing. Whereas if I use B mode, it decelerates so aggressively that I often have to use the throttle to speed up more frequently. I've also noticed that there's a very slight bit of added resistance when driving in B mode. If anyone wants to try this out, just drive at a standard speed in B mode, say 45mph and then shift into D mode. What I feel is perhaps a very slight gain in forward momentum, perhaps equivalent to 1-2 mph. Does anyone else notice this? Is this a deficiently of B mode, or is my car broken? What about any damage to the battery for the large amount of regen in B mode (equivalent to QC speeds?)

Lately I'm only using B mode if I know I'll be coming to a stop up ahead and can use the more aggressive regen, or if I'm going down a very steep hill.
 
I'm no expert on this newer Eco+B mode since my wife has the 2015 and I have a 2012. When I have driven it, I guess you drive more with the throttle, all the time. When you want less regen braking, you keep your foot on the throttle, just less than you would with full on regen braking. My 2012 has a nice screen that shows me a pie chart scale of power out and power in. I usually refer to that when I want to see if I can coast (foot still on the throttle) but not putting energy into the motor and then release it further to start pulling energy back and slow down the car before having to use the brake pedal to ask for more regen before the brakes really do kick in.

Eco mode in the 2012 pulls in twice as much regen off throttle (no brake) than the normal D mode does, I like how the 2012 eco runs. My wife never uses the B-mode as it harder to master unless she's going down a long slope that would otherwise need some braking to maintain a safe speed.

Practice is the journey to perfection.. which is always out of reach. Enjoy the journey though.
 
I have similar experience like yours

I think B or D mode controls amount of regen (braking) and Echo mode controls amount of acceleration

So with B, D, B+Echo and D+Echo, we have 4 modes of combination for driving.

B - Max. acceleration, Max. Regen.
D - Max. acceleration, Min. Regen.
B+Echo - Min. acceleration, Max Regen.
D+Echo - Min. acceleration, Min. Regen.

This is from my own experience.
 
It's all on how you drive it. By definition, regen doesn't recapture but a fraction of the energy used to accelerate the car. If you use D mode, but keep the acceleration under control, and use D mode to do more coasting and use a light foot on the brake pedal so that you mostly regen to stop, then I think you can beat the scenario where someone uses B+ECO to do a lot of extra regen. If on the other hand, the guy using D mode ends up doing a lot of hard braking, he'll do much worse than the B+ECO.
 
I have seen my dash display as high as 6.1 miles / kWh after a round trip commute, and I drive in D and shift into neutral as often as possible; using regen only when I have to slow down.

The Leaf coasts really well, and I have the stock tires at 45PSI. My best measured charge (using my Juicebox Premium) is just under 207Wh/mile. I think that is very good, and I am driving at normal speeds; though not often on the highway.
 
I drive in B mode all the time. No ECO unless it is in winter to limit heater power. It's all about modulating the accelerator to keep it near the neutral bubble as often as possible. Then I still have the full regen available at a moments notice, no shifting required. My normal commute is in heavy traffic with lights, hills, and 55-60mph speed limit. I average around 5.2 mi/kWh in good weather.
 
Hi all, I'm brand new - just got my pre-owned LEAF SV (+QC and premium package) on Monday. I've noticed more than one person mention coasting downhill in neutral, but tried that the other night and mine does not got into neutral while the power is on. I was only able to get it to neutral while the main power was off (would toggle between N and P only). Once the car was booted up and ready to drive, the only options were R, D, and B, no neutral. Is that normal for my MY or am I missing something?

Cheers,
 
Wendy,

To put my 2013 Leaf into neutral, I hold the "puck" to the left center for approximately 1 second. It won't go into neutral on a short pop left. It has to be held there.

If that doesn't work, perhaps something is wrong with your Leaf.

Bob
 
You can also put it into R while driving and it will be forced into N. It beeps when you do this, but I don't think it hurts anything. I won't do it on a regular basis though.
 
Interesting observation. I think a lot matters based on driving style as the two modes seem to me to require different handling to be efficient. If you're practiced on efficient driving in D and switch to B and don't change you driving style, I can see how you would get worse performance as these seem to require different feathering of the pedal.

From my experience, my efficiency went up when I switched to exclusively B mode. But you pose a good question.
 
I shift into R to get to neutral all the time. It does take a different type of driving, but coasting is inherently more efficient, for two reasons: you accelerate less, and you use the kinetic energy of the moving car more efficiently. In other words, you "invest" less energy to get the car moving, and you then cover more distance as well.

Coasting down hill / down slope is road candy.

Of course, regen is still great for slowing down - when you need to slow down. But to accelerate so much that you then need to scrub speed, you have already wasted energy, and regen loses energy relative to coasting, because of mechanical and electric loses that are inherent. Aero and rolling friction are always present, and they are the only loses when coasting.
 
tkdbrusco said:
So I've started to drive my MY15 in D mode more frequently than B mode. I was always under the impression that B+Eco was the best for range and efficiency, but it seems like that's not the case.

My average efficiency in B+Eco was 4.7mi/kwh and my average efficiency in D+Eco was 4.9mi/kwh. I've been driving a nearly identical commute in D+Eco for 1000 miles, so I would assume that these numbers are pretty accurate and would indicate roughly a 4% benefit overall? My GOM readings have also improved, not that this is any real measure.

Here's what I'm thinking, D mode doesn't decelerate as aggressively and thus allows you to coast further. If you feather the throttle, you can actually coast in D mode with one green dot showing. Whereas if I use B mode, it decelerates so aggressively that I often have to use the throttle to speed up more frequently. I've also noticed that there's a very slight bit of added resistance when driving in B mode. If anyone wants to try this out, just drive at a standard speed in B mode, say 45mph and then shift into D mode. What I feel is perhaps a very slight gain in forward momentum, perhaps equivalent to 1-2 mph. Does anyone else notice this? Is this a deficiently of B mode, or is my car broken? What about any damage to the battery for the large amount of regen in B mode (equivalent to QC speeds?)

Lately I'm only using B mode if I know I'll be coming to a stop up ahead and can use the more aggressive regen, or if I'm going down a very steep hill.
It may seem counter intuitive because B mode with more regen would seem to be the more efficient way to drive, but it really comes down to the fact that whenever you have to regen, you are losing power. Granted, not nearly as much wasted energy as an ICE vehicle because they are basically generating pure heat to stop through the brake pads. The leaf has brake pads too, but you are trying to recapture that energy to stop and waste as little as possible making heat via the brake pads. When driving, if a perfect example was a straight, level road 20 miles long, no traffic, no stops, then it would make no difference between driving in B or D mode. But since we all have a variety of driving conditions, we expect stops, slow downs, speed ups, etc. You would find that with more work, you could drive just as efficient in either mode. The issue is we don't always want to micro-manage our driving when we have to pay attention to traffic and road conditions. So for long, easy trips down a country road, D mode gives the best range. When driving through a lot of stop and go traffic, B mode would give the best range (you won't be riding the brake pads as much, losing energy). So the large variety of modes combination is like a toolkit for the car. No one single mode is perfect for all driving conditions, but there is a best mode for every type of driving condition. :D
 
Nope.. on a FLAT road.. set the cruise control.. then toggle between eco and D.. should be no change at all
again in D-B and Eco-B. should be no change at all.

now.. if there is grade... eco's power restriction will just slug along.. while toggling to D will make the car jump !

I wondered if there were some "drag in B".. but I think it's psychological.. but I don't try to cruise in B.
if theres bats in that box.. I don't want it open either !

:roll: :lol:
 
From what I've observed on my 2016 SV (as well from studying the service manual), the different modes re-map the accelerator pedal.

It appears that activating cruise temporarily overrides Eco even though the Eco indicator is still on. This is evidenced by the change in GOM miles and Eco Tree instantaneous meter. I don't know yet if cruise also overrides the climate control power limit, but kind of doubt it.
 
I really feel like there is some drag in B mode. When driving on a flat straight away if you shift between the two you will feel it and you will see sometimes an extra accelerator bubble. I almost never use B mode anymore unless it is a serious downhill.

Driving D+Eco with 42psi in my tires my average efficiency is 5.0 mi/kwh
 
tkdbrusco said:
I really feel like there is some drag in B mode. When driving on a flat straight away if you shift between the two you will feel it and you will see sometimes an extra accelerator bubble. I almost never use B mode anymore unless it is a serious downhill.

Driving D+Eco with 42psi in my tires my average efficiency is 5.0 mi/kwh

You are feeling the pedal being remapped. I drive on the highway in B mode plus Eco regularly (when there are numerous roundabouts) and there is no "drag" other than increased regen. That little extra regen when you "shift" into B may be there to let you know that you've done so.
 
I have a digital piano that can make the keys feel heavier at the push of a button. All it does is remap the loudness response to key press velocity. Our brain interprets that as if something physically has happened: like somehow stiffer springs have been added to each key. Also like Apple's haptic click trackpads: you'd swear there is actually a button clicking, but it's a clever illusion.

Eco / B modes on the LEAF can leave (ha) you with a similar feeling, when all that has been changed is the motor power/regen response curves to accelerator pedal position.

Something similar can happen if regen cuts out while lightly braking on a level road, the feeling is the car is suddenly accelerating when in reality it is still slowing or at least coasting.
 
tkdbrusco said:
So I've started to drive my MY15 in D mode more frequently than B mode. I was always under the impression that B+Eco was the best for range and efficiency, but it seems like that's not the case.

My average efficiency in B+Eco was 4.7mi/kwh and my average efficiency in D+Eco was 4.9mi/kwh. I've been driving a nearly identical commute in D+Eco for 1000 miles, so I would assume that these numbers are pretty accurate and would indicate roughly a 4% benefit overall? My GOM readings have also improved, not that this is any real measure.

Here's what I'm thinking, D mode doesn't decelerate as aggressively and thus allows you to coast further. If you feather the throttle, you can actually coast in D mode with one green dot showing. Whereas if I use B mode, it decelerates so aggressively that I often have to use the throttle to speed up more frequently. I've also noticed that there's a very slight bit of added resistance when driving in B mode. If anyone wants to try this out, just drive at a standard speed in B mode, say 45mph and then shift into D mode. What I feel is perhaps a very slight gain in forward momentum, perhaps equivalent to 1-2 mph. Does anyone else notice this? Is this a deficiently of B mode, or is my car broken? What about any damage to the battery for the large amount of regen in B mode (equivalent to QC speeds?)

Lately I'm only using B mode if I know I'll be coming to a stop up ahead and can use the more aggressive regen, or if I'm going down a very steep hill.

your ideology only works in a "one size actually fits" World. problem is... it normally does not fit.
 
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