Unclear on regenerative braking

surfingslovak said:

You might want to peruse Stoaty's Guide to the Efficient Driving of the LEAF. But then getting anything above 7 m/kWh is very impressive in its own right.

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Mind-blowing, to me. Anything much over 5 m/kWH means I'm paying strict attention to efficiency.

RonDawg said:

Stanton said:

Seems to me that 3.5 m/kW is a bit low (unless it's colder in LA than I think); I consistently get 4+. (snip)

Bottom line: acceleration and (top) speed are the real killers of EV range (OK, and cold temps)

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Don't forget hills. Although the OP said he doesn't drive too many hills, LA's Silverlake neighborhood boasts streets that will rival anything in San Francisco when it comes to steepness. Go to YouTube and type in "Fargo Street Hill Climb" for a list of videos of people trying to travel up what is possibly the steepest street in the entire state (32% incline) on just human power.

3.5 miles/kWH is pretty much what I average. My commute is not as steep as Fargo Street, but it is for a much longer distance, and is a net elevation loss/gain of 1,000 feet.

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I just checked our elevation - about 550 feet. It is indeed a steep but short (half mile) hill up to our house - we can watch the GOM freaking out as we climb, and in the Prius we lose about 2 mpg just for that short stretch. I know Fargo and all those steep ones around here, like Baxter and Cove, often get my exercise walking up - quite a bit harder walking down (also do all the public stairs). Definitely have to lean forward to keep from toppling backward, and driving them is kind of intimidating. No mere regen going down those hills. Your 3.5 m/kwh makes me feel a little better.

surfingslovak said:

You might want to peruse Stoaty's Guide to the Efficient Driving of the LEAF. But then getting anything above 7 m/kWh is very impressive in its own right. Unless it was all downhill, of course. I think many here can relate to the sense of learning how to drive all over again. I even specifically mentioned it in a blog post a year ago. Congrats on your new 2013.

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Well, I sometimes wish it were a 2013, with a 6.6 charger in front, but it's a new 2012 SL that the dealer had to sell, so we got it for less than a new 2013 S, and with the state rebate and fed tax credit, it'll come out to about $16K - how could we say no to that? Besides we couldn't wait for the 2013s - our ancient had Honda died. I hope that when we're ready to trade in the Prius, the technology will have progressed to the point where Nissan will have given the Leaf a Tesla-like range and there will be charging stations everywhere.

When my wife took Laurel Canyon Bl. to Burbank, she started at about 100 ft elevation and topped out at about 1100 in about 5 miles, so that would have decimated her m/kwh. Then it's all downhill to Burbank.

ronwright38 said:

I can take my foot off and when it is coasting the Regen light's turn Green and work's in the 2013 and in B mode.

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Definition: Coasting is when the motor is not being used, neither to provide power to the wheels nor to absorb power from the wheels. When you take your foot off the accelerator and leave the car in Drive or ECO or B, you are not coasting. You are regenerating. Regenerating is much better than braking, but it is not as efficient as coasting.

Ray

Automotive terms, like many words in our language, suffer continual torture from over use by the masses. Just have to accept that a lot of folks think of "coasting" as "I'm not stepping on the pedal". You have to read between their words to figure out what they're thinking.

Responding to the OP being told "regen is inefficient": What they're really saying (between the lines again) is that you really want to avoid being in a situation where you need to slow the car down. I got this -> :roll: <- one time for asking a similar question ("Do I slow down gradually or wait until the end?")--all they could tell me was that I shouldn't have put myself in that position to begin with. BTW, the Prius DVD told us several times that we should "brake in good time". Had some fun figuring that one out.

Also wanted to mention that when you see MPK figures from folks in Arizona, Florida, (and maybe Texas)...be aware that their roads are flat, their batteries are warm, and they can't understand what all the fuss is about not being able to go 100 miles. It's a regional thing. Here in So. Cal., that mesa-canyon-mesa-canyon-mesa thing keeps me right around 4.0 MPK. Well, that, and the fact that I don't like to go slower than the flow of traffic

planet4ever said:

ronwright38 said:

I can take my foot off and when it is coasting the Regen light's turn Green and work's in the 2013 and in B mode.

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Definition: Coasting is when the motor is not being used, neither to provide power to the wheels nor to absorb power from the wheels. When you take your foot off the accelerator and leave the car in Drive or ECO or B, you are not coasting. You are regenerating. Regenerating is much better than braking, but it is not as efficient as coasting.
Ray

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+1

wlegro said:

I just checked our elevation - about 550 feet. It is indeed a steep but short (half mile) hill up to our house - we can watch the GOM freaking out as we climb, and in the Prius we lose about 2 mpg just for that short stretch. I know Fargo and all those steep ones around here, like Baxter and Cove, often get my exercise walking up - quite a bit harder walking down (also do all the public stairs). Definitely have to lean forward to keep from toppling backward, and driving them is kind of intimidating. No mere regen going down those hills.

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Going downhill is the worst IMHO. As you approach from the top, the streets' severe steepness makes it look and feel like you're driving off the edge of a cliff

kovalb said:

To improve energy economy. Whenever possible prioritize in this way:
1. Coast as long as possible. I use the A-pedal to zero the power. This provides the best control. I tried using "N" but it takes time to reengage "D" or "ECO" in the event you suddenly need power.
2. When you need to slow, lift slowly from the A-pedal and use regen. If you do not need to slow as much as the regen provides then tip in slightly into the A-pedal to modulate the regen.
3. Finally when braking is necessary, do it as smooth and gently as possible.

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Exactly. It seems that some people have the mindset that coasting is better, and in some cases it is. However, you can effectively coast by modulating your accelerator. It takes practice. It will seem that you're having to learn how to drive again. It's challenging on a bumpy surface. But it's the same thing. Since the electric motor doesn't have a clutch to physically disengage itself from the drivetrain, properly modulating the accelerator is the exact same thing as coasting, except without the danger of being unable to accelerate in an emergency situation.

I've just purchased and started using my 2019 Leaf 1.5 months ago. I live in Montana where we get 9 months of the year cold/cool temperatures. So far I have 1900+ miles on this car. I've always drove my car/truck with hypermiling mode. Treating the A pedal like a feather and always scroll down to intersections without using B Pedal. This is the case on all ICE and this EV car. With N, D, B, EPedal features I've been playing with and trying to find the best ways to get the most efficiency out of this Leaf last 1.5 month.
Here is my findings so far:

First: I put this car on N while I was driving one time. I will state some facts below doesn't mean I do them or you should do them.

Second: I rarely use the heater and AC and rear defroster. If I start my leaf and leave it at P (Park) for an hour with heated seats and heated steering wheel I won't loose any range.

N driving: Say there is this downhill road for 30 miles and speed limit is 60mph and say you put your car in N mode and it goes right around 60 to 65mph with no need for break or accelerate. Hey this is the most efficient mode you could be in but there are not too many roads like this. You will either go too fast or too slow. This is just a scenario to make you understand.

D driving: On the way to work I loose about 600ft on elevation and usually the wind is behind me. I use D mode and it is 60mph speed limit. Drive around 50-55mph and get 5.4 miles/kWh. Hey it is 6AM in the morning nobody behind me no need to rush.

B driving: Usually in town when there is not much stop and go. On Icy roads B mode work very well on slow speeds.

EPedal ON: When there is a lot of stop and go, in heavy traffic. On pack snow, slippery winter roads ePedal is ON and it performs very well.

ECO: Usually leave it off as it is not economical to leave it on. I've done some test and regularly I get work miles/kWh

Basically there is no one most efficient mode to drive this car. It all verify depending on what type of a road conditions that I am in. You just have to figure out the most efficient mode on when to use it.

These are my findings so far. It might change as I put more miles on this car. So far I've used about $57 of Electricity on 1900 miles and very happy about that. My F350 could chug that much diesel in 200 miles when I am towing my camper. LOL

Congratulations on your new car. I know it is fun to experiment with your new car. I did the same thing when I got mine. I really don't think that playing with "coasting" with or without gears or eco really makes a difference.

I like just leaving it in eco mode, and just driving it without big accelerations and letting the car regen slowly when I see a red light in the distance. Anything more than that is really more mental work than I will allow myself for any car. Changing the efficiency by any small percent will save me..... What..... $25-50 cents?

PS - Regarding the heater, you should not suffer without a heater. I put it at 68 degrees, in recirculate mode, and with the fan at 1. While the car is never HOT, it keeps me comfortable, and I do not use a lot of the battery...

ECO: Usually leave it off as it is not economical to leave it on. I've done some test and regularly I get work miles/kWh

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Eco is more efficient for most people, because it makes it harder to accelerate quickly unless you really mean it. It also limits heater consumption. Why do you say that it "it is not economical to leave it on"?

Another "glitch" which can affect efficiency is at what elevation you start your car. My first three or four miles are all either level or downhill. After an overnight full charge I have only one regen double circle left since there is little or no room to "stuff" more juice in the battery. Without regen available, when you lift your foot off the A pedal you really do "coast". I pick up rolling speed much faster than if I headed out of my garage with a half charge. Putting it in B does not make a difference since, no matter what, you are not getting any more regen. I also see the GOM go up 2-3 miles by the time I reach bottom.

I try not to touch the A pedal and allow the car to slow down as much as possible on the levels so my downhill speed does not pick up too much. Limited by the traffic though. I'm not goring to do 15 mph in the 35 mph zone, holding up traffic behind me. During these first miles the brakes are truly "old school" kinetic energy to waste heat convertors.