B-mode for regular driving

gatedad11 said:

This week, I tried using "B" for anytime that I need to accelerate the car forward, then once I see an impending stop, switch to "N" and finally take my foot off of the brake.

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I don't understand what you're doing because in 'N', there is no regenerative braking, so your braking would be totally friction braking which is very inefficient. Are you using 'N' for coasting prior to braking and then shifting back into 'B' before braking? If so, that's certainly a lot of shifting when you can coast in 'B' by merely positioning the accelerator pedal so that no electrical current is flowing in or out of the motor/generator.

alohart said:

...Are you using 'N' for coasting prior to braking and then shifting back into 'B' before braking? If so, that's certainly a lot of shifting when you can coast in 'B' by merely positioning the accelerator pedal so that no electrical current is flowing in or out of the motor/generator.

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alohart, I personally find it MUCH easier to simply quickly shift into 'N' instead of trying to carefully balance the red power needle midway between the blue and green regions. Besides, I consider doing that quite a distraction when driving. When using the heater that spot is NOT the zero-regen location, and actually results in unnecessary regeneration. My vote goes to using 'N' whenever possible, and simply shifting into the D-E-B when one needs to slow down. Having driven stick shifts all my life, playing with our clunky lever doesn't bother me at all - and I may well be the first person to wear it out, if there is such a thing.

I just took home my raspberry SE today, and am excited to figure out my own favorite methods of driving it.

While attempting to coast in B, I noticed how easy it is to suddenly start breaking, causing a bit of an awkward ride and likely annoying and confusing the poor bastards behind me, considering my brake lights weren't going on. I'll probably get better at it with time, but I doubt it will become my go-to mode. I shouldn't drive more than 30-40 miles (much of it freeway, on the downside) mosts day, so hopefully range-optimisation will be more of a fun thing to experiment with than a necessity.

The salesman, who has traveled to some EV conferences and gone through all the training (unlike most of the other salespeople I dealt with), said it was fine to drive in any of the modes any time.

For me, the idea of always coasting and never using breaks seems impractical without impeding traffic by slugging along at 10mph. You've always gotta apply some breaks, right?

You can with experience drive without using brakes and not being an annoyance for other users.

The brake will eventually bemused for emergency or right before stoping the car!

Related question: does the i MiEV light up the brake lights when regenerative braking on the accelerator pedal is used? (I *think* the Tesla Model S does do this?)

No, the brake lights do NOT illuminate. I tested this at night near my house. During braking, I could see the reflections of my brake lights in the street signs. Then I did a full B-mode regen pass by the same signs -- no brake lights.

I personally think this is a safety issue, but it's also quite amusing in the right situations. A woman was tailgating me on the freeway one day, so I just let off the accelerator in B-mode. She panicked and slammed on her brakes. I used to have to downshift my ICE for the same effect. :lol:

@nsps: Welcome to the community! I wanted the raspberry color but couldn't get it with my lease deal. Practicing driving in B-mode will eventually smooth you out. JoeS is right -- when you use the heat, the eco/regen needle is skewed a little upward. In that case, coasting with B-mode becomes more difficult.

My dad, an auto engineer with another company , agreed with my thoughts: Skill level increases as you go from D to E to B. D doesn't take any extra thought to drive. It's the mode people select as default. E takes a little more skill because the regen is stronger and power output is throttled. B is expert mode. Takes practice and concentration. I still haven't perfectly mastered a slower coast-down on a bumpy road in B-mode.

JoeS said:

alohart, I personally find it MUCH easier to simply quickly shift into 'N' instead of trying to carefully balance the red power needle midway between the blue and green regions. Besides, I consider doing that quite a distraction when driving.

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I don't bother with attempting to balance between blue and green regions; I just adjust the accelerator position to maintain whatever speed is appropriate. Pure coasting in 'N' doesn't usually result in maintaining my desired speed due to rolling and aerodynamic resistance (unwanted deceleration) or gravity (unwanted acceleration), so I find that maintaining speed with the accelerator while in 'B' to be the most satisfactory and the most safe (no need to take my hand off the steering wheel to shift into gear). I am under no illusion that driving in 'B' without paying very close attention to the power needle results in the ultimate efficiency, but it's close enough for me.

alohart said:

I don't bother with attempting to balance between blue and green regions; I just adjust the accelerator position to maintain whatever speed is appropriate. Pure coasting in 'N' doesn't usually result in maintaining my desired speed due to rolling and aerodynamic resistance (unwanted deceleration) or gravity (unwanted acceleration), so I find that maintaining speed with the accelerator while in 'B' to be the most satisfactory and the most safe (no need to take my hand off the steering wheel to shift into gear). I am under no illusion that driving in 'B' without paying very close attention to the power needle results in the ultimate efficiency, but it's close enough for me.

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That's my experience also, word for word

It is so second nature for me now that I think it probably does get me the best range also, since I regularly get 75 to 85 miles per charge . . . . constant use of the 'B' mode isn't costing me any range, that's for sure

Don

You need to choose your occasions for free wheel coasting - down slopes are great (I call them road candy!) or approaching red lights or on short roads where you have to come to a stop anyway. You have to try it on the roads you drive every day and learn where you can use it effectively. Say you accelerate for 50-60% of the distance of a road, and then coast for 30-40% and then use regen only at the last 10% or so, you will lower your Wh/mile average. Or, accelerate up the hill, coast down the other side, accelerate again on the flat or up the next hill - if you start accelerating before the bottom of the down hill to gain speed to climb another (what I call swooping) this saves energy overall. If you coast toward a stop and use the regen then brakes to come to a stop at the end of the coast, you will be ecodriving.

If you pump up your tires to the sidewall max (or close to it) that will help extend the coast some. Smooth wheel covers are a simple aerodynamic mods that will also help coasting, and reduce drag for all driving, too. The point is to shorten the time accelerating (which saves the energy up front) and then coast when you can, using the brakes to only stop at the end. And coast down slopes and hills as you can. The kinetic energy is used 90%+ when you coast to move the car, but with regen you lose about 40-60%.

What I do(and I am still experimenting, after all) is use B or D mode, then switch to N whenever it is safe and will not cause the car to slow down(too much), such as on straight of ways where I can coast a good deal and then will go to E then B, and finally braking. or, as has been mentioned, use B or D uphill and N to coast downhill. Obviously you can't use N to brake...at some point you must use your regenerative mode and then finally apply the brakes. What I thought I'd mentioned was that it has to be done with common sense, if there are cars behind you or you will be faced with a lot of stop and starts, N is not very useful. But my commute to work involves a lot of gently sloping hills, where I can reach the top, put it into N and coast. Once the cars slows down too much I go back to D or B, then repeat the process where it is practical and safe. It seems that I only hit brakes without D or E when I just cannot time it that way. For what it's worth, after my Friday commute in the car, where I was only using this N mode much for half of my commute, the next day's range remaining showed 93 miles. That's the most I have seen to date. On this morning's 17.5 mile commute, I used 11 miles on the RR battery. I understand that the RR is not 100% accurate, it estimates remaining range based on prior driving habits...but it seems to suggest that using N a good deal of the time, along with E and B for slowing down works!

Lou

Hello Lou,

Yes, coasting (in neutral if we must) is for when you want to carry as much speed as possible. And use D, E, or B for varying levels of regen when you need to slow down. That is in a nutshell, the most efficient way to drive - adjusting the nut behind the wheel!

If an EV had no regen on the accelerator (as the Honda Fit EV in Eco mode and the upcoming VW e-Golf does, as well), then in stop and go traffic, you could have the benefit of coasting for short distances without having to shift, and therefore be able to accelerate instantly without having to shift at all. All the regen should be on the brake pedal, since that is the function of that pedal - to slow down and stop the car. The "go" pedal and the "stop" pedal makes it so you become accustomed to how your car coasts - and you accelerate significantly less, then coast, then depending on the drive, you can accelerate some more, or slow to a stop with the brake pedal.

You save energy in two ways: less acceleration to begin with, and less loss because coasting uses almost all of the kinetic energy to move the car, rather than regaining only about half of the kinetic energy stored back in the battery.

Well, after a week and a couple days of driving the car, I do enjoy driving in B mode. I'm not sure that it's technically any more efficient than D mode, but it does allow you to adjust the speed of your coasting precisely on the throttle, rather than by switching back and forth between pedals. My commutes generally don't involve stand-still traffic, but there are enough cars around and in front of me that coasting all the way to a stop won't work. That said, I try to adjust my driving to that I only use the brakes when I have to. If B mode kicks in and then I have to use power before coming to a complete stop (or slowing as needed for surrounding traffic), I consider it a misstep.

I'm sure it's been discussed here and might even be covered somewhere in the manual, but I would be interested to know if there's a sweet spot at which charging is most effective, or a spot where it becomes less effective. My assumption is that more energy will be lost with sudden slamming on the brakes compared with slower coasting and deceleration. If the needle is pinned back, is that bad?

As a rule, except if there was an emergency or you would have disturbed traffic, you should not be needing to brake nor have the regen often all the way down. If this happens then it means there would have been room for more anticipation.

In other words for a given path, you go away from the optimum if you have to slam on the brakes or have the arrow often go above and immediately below regen.

Again, safety in traffic is more important Than hypermiling.

NeilBlanchard said:

The "go" pedal and the "stop" pedal makes it so you become accustomed to how your car coasts - and you accelerate significantly less, then coast, then depending on the drive, you can accelerate some more, or slow to a stop with the brake pedal.

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This is exactly how most drivers operate an ICE with an auto trans . . . . without even knowing they are doing it. They are basically gently accelerating until they notice they are going a bit too fast and then 'coasting' back down to their intended speed and then when they notice they're going a little too slow, they gently accelerate again - Back and forth, off and on the go pedal. This is why cars with auto transmissions get significantly less fuel economy than cars with manual transmissions where the engine is directly connected to the wheels. Manual trans cars don't 'coast' (the decelerate when you lift off the pedal) so those who learned to drive with them get in the habit of maintaining steady speeds, and consequently, they get better fuel economy

With EV's, you have no choice in the matter - The engine is always directly connected to the wheels, so you have no freewheel coasting, even if you 'shift' it into 'neutral'. Calling this shifter position 'Neutral' is kind of a misnomer anyway, since all that position really represents is the lack of any regenerative braking. When you 'coast' down a hill, the car is still consuming some kinetic energy speeding up the motor because you cannot disconnect it from the wheels. If, on the other hand, you get in the habit of driving by maintain steady speeds and using engine braking whenever you purposely need to slow (not braking, just slowing) you can get better economy. In everyday driving, the actions of other drivers and traffic makes it necessary to speed up and slow down even when you don't really want/need to, so you might as well take advantage of that unintended slowing by getting something back from it - Regenerative braking. Thank heavens you don't need to be pushing on the friction brake pedal to activate this feature. Keeping the two separate is one of the few things they didn't do to try to emulate the bad habits of ICE cars when they built this car!

An EV can 'unlearn' many of your auto trans bad habits . . . . if you'll let it

Don

Llecentaur said:

As a rule, except if there was an emergency or you would have disturbed traffic, you should not be needing to brake nor have the regen often all the way down. If this happens then it means there would have been room for more anticipation.

In other words for a given path, you go away from the optimum if you have to slam on the brakes or have the arrow often go above and immediately below regen.

Again, safety in traffic is more important Than hypermiling.

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Lucky for you, you're obviously not driving in the same traffic I am. If I was the only one on the road, I could s l o w l y creep up to my intended speed over the course of a block or two and slow the same way - But frequently, the actions of other drivers cause me to slow when I don't desire to and seeing the needle in the blue 'Regen' zone means I'm getting something back for wasting the energy that slowing a 2500 pound mass represents. I'm also never going to be comfortable being the guy with nobody in front of me and 10 or 15 drivers hemmed in behind me who wish I had never left home . . . . or at least , not left where it put them having to follow me. I have always tried to move with the flow of traffic, both accelerating and slowing . . . . and for nearly 50 years, I've done it by using the brake pedal as little as possible

I LOVE driving an EV with Regenerative braking - I only wish I had more of it! I wish 100% regen was available without touching the brake pedal . . . . then I'd be back to driving as I've always done . . . . downshifting my manual trans to slow

Driving in traffic and using the B mode makes touching the brake pedal pretty much unnecessary if you follow at proper distances and anticipate the actions of traffic . . . . I love seeing the needle in the blue whenever I'm forced to give away some of my kinetic energy

Don

Superior regeneration (over the Leaf) was one of the two primary reasons I purchased the iMiEV, and I agree with Don that more is better, but there are also driving situations where I like zero regen.

Efficiency is strictly dependent on the driver, with each 'shift' position having its attributes and which some of us favor over others. Personal preference.

nsps, if you're interested in extracting the maximum mileage from your iMiEV, you might peruse this thread: Hypermiling the iMiEV (which I have yet to finish). If nothing else, it's a good skill to acquire for the few times you really need to extend your range.

As I've said before, my preference would be a (dash-mounted?) control to vary the magnituide of regen from zero-to-max and a paddle by the steering wheel which would let me manually apply regen.

JoeS said:

As I've said before, my preference would be a (dash-mounted?) control to vary the magnituide of regen from zero-to-max and a paddle by the steering wheel which would let me manually apply regen.

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That sounds GREAT Joe, though I'd prefer a dash mounted adjustment and then a paddle for when I want no regen . . . . hold the paddle to coast so to speak

We need to see about making this happen - It would be the ideal mod . . . .

Don

Don said:

…seeing the needle in the blue 'Regen' zone means I'm getting something back for wasting the energy that slowing a 2500 pound mass represents. I'm also never going to be comfortable being the guy with nobody in front of me and 10 or 15 drivers hemmed in behind me who wish I had never left home…

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I agree here. When we can get by without wasting any energy that's great, but when we have to it's good to know that at least some of it is going back into the car, unlike in a traditional ICE vehicle. Obviously we're more conscious of energy because of range limitations, but the energy is being wasted either way.

Lifting your right foot off the accelerator in gas car in Drive is not free wheel coasting - there is engine braking, and this is what most EV's are designed to emulate. That is the problem - it is not the most efficient way to drive. By the way, there are other reasons that automatic transmissions get lower mileage than manual shift: they have slippage in the torque convertor, they have creep which means they are pushing against the brakes when they are sitting still in Drive, etc. ICE's also idle during coasting which an EV's avoids.

I'm beating the EPA Combined rating by 40-75% on my Scion. I know it is harder to beat the EPA rating on an EV's because they are already doing some of the things that ecodriving does: shutting off the engine during coasting (I bump start at the end of the coast), and I shut off the engine at long stop lights. Another point that needs to be made: with lower aero drag, a car coasts better - I have made a number of aerodynamic modifications and reduced the Cd by about 10%. These raised my mileage and account for about half of the increase I am getting.

Hi guys, We are still keen on getting an iMiEV, but with no recharging stations here yet, and each fast charge one we have looked at bringing in ourselves being in development still, or really expensive, until the $ 17, 000 NZ version is available, we have been looking at alternatives for both short, and long range use.

Recently, we took a Prius C for a test drive over a long weekend, from Friday 4 pm to about 2 pm on Monday. On Friday and Saturday we did about 160 Kms combined, and on Sunday we went for a long drive to Kaikoura, with a meal stop in Cheviot, and again a meal in Kaikoura prior to the long trip back. Total for there and back was about 395 Km.

The trip gave us a 4. 7 litres per 100 KM economy at speeds below our normal 100 Km / Hr which we could do as there was very little traffic.

The trip on Sunday used $ 40.00 of fuel which is about 20 litres of 91 petrol. The trip on saturday for about 80 Kms used about $ 7.

The boss was staggered when he filled up after the trip on Sunday to see the car stopped filling at about 17 litres and he managed to get about 19 litres in. Normally, our Adventra would use $ 120 or so for the same trip. About 59 litres.

We had a talk about the fuel costings and the price of the car, and did sums comparing the iMiEV, the Nissan Leaf and the Volt.

If we didn't have to allow for interest on the purchase cost, i.e use cash for the purchase instead of a loan, the iMiev, followed by the Nissan Leaf followed by the Volt followed by the Toyota for around town driving would be best.

Because each firm is charging different interest and has differing pricing to start with as well, and differing fuel and electric economy it gets more complicated, but in the end we decided we would buy two cars..the Mitsubishi iMiEV for around town and longer trips when charging stations are available on route, and the Toyota Prius C for longer trips until the recharging stations are available or when time on trip is important. That is, when no time is available for recharging at fast stations.

How does this all fit into the B- Mode discussion ?. Well, we tried B mode on the imiev and loked it a lot, very easy to drive with in start go traffic and on hilly windy roads. On long flat bits the D mode is good too. Kind of like driving in third on a manual Hilux for B and like 5th in D.

The Prius C though acts differntly in B mode, the take off and driving along is more noisy as the petrol motor acceleration goes high and holds a higher revs than in drive mode until it reaches the speed you are aiming at then it goes quieter.

In Drive it acts like a normal automatic except it seems to not change gears, just a normal constant acceleration movement feel.

In B mode while slowing though from a high speed to a lower speed, say on a downhill slope with corners, the engine races as the cars works to slow down on engine and electric braking, then become normally quiet again as the speed of the car matches the engine note.

Touching the brakes lightly adds more regen and putting more push in the brakes will adds heaps of regen then as the cars slows to almost a stop there is a reduction in braking so more of a push is needed, just slightly though.

So for a more relaxed quieter ride, leaving it in D mode is best and applying the brake slightly to get the regen working hard until the speed is lower, then putting in B to hold the speed while going downhill or through corners seems to work well and is quieter.

The Consatntly Variable Transmission is ok, but a bit disconserting to someone like me more used to a Manual or auto that has steps in gears. Interestingly, it has Cruise control and on setting a speed and a downhill makes the car speed up, the car then slows to the set speed by using regen ! cool.

So for now, subject to finance, we will get the Prius C and then once the iMiEV is slightly cheaper or recharge stations are available, we will get it. I far prefer the driving of the iMiEV though in terms of quietness and fuel savings, and it is fun to drive.

The Prius C though will allow me to go to the Sounds to see my boat, which due to work and the high cost of fuel, which means a day or two is all I can get off and it costs $ 255 or so to go there and back, comapred to the imiev being $ 24 or the Prius C being $ 80.

For $ 80 it seems reasonable and I can then nip off to the sounds after work, stay on the boat and then come home later the next day, refreshed for the next day work. At $ 255 I had to have at least three or four days off to make it worth while.

Still, I am keen to see fast recharge stations pop up along the route and even if it adds another 4 hours to the trip recharging, expected is another 90 minutes for three rechargers , it would be so cool to travel for only $24.

If using the imiev, as here are a lot of stop start traffic on the way and lots of hills and corners for much of the way, I will proberly leave the imiev in B.

On the trip to Kaikoura and back we spent $ 45 on food and $ 40 on fuel in the Prius C. The Holden on the same trip would have been $120, before food for us, so we proberly would have had $10 of Macdonalds between us two people instead, grin.

Putting it another way, if we took the imiev and allowing for recharging , we could take four people and shout them a $ 5 Macdonalds meal each stop, and be cheaper than fuel for the Holden...