wlegro
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Re: Unclear on regenerative braking

Sun Mar 24, 2013 10:57 am

planet4ever wrote:To emphasize a bit more what Gary said, coasting is either shifting into Neutral Ray


No, I never shift into Neutral - too much loss of control, especially in congested traffic, which is all there is here.

planet4ever wrote:or the rather difficult trick of watching the left pie chart on the center console Energy Usage display and keeping it blank Ray


Well, along with terminology, I'm gauge-challenged. I try to watch everything and figure out what it is, but it's a little nerve-wracking in our traffic, and I haven't found the manual much help, though I'm also manual-challenged. Our other car is a Prius - same issues. Maybe I shouldn't even be driving these kinds of cars. :lol: If by the pie chart you mean the gauge in the upper left corner that adds or removes slices of pie depending how you're driving, I do watch that - it's the equivalent of the power column in the Prius, I think. I try to keep as many slices of the pie as possible. Come to think of it, that's how I eat pie, too. :)

planet4ever wrote:The closest I come is moderating the accelerator so that only a single dot shows on the dash.Ray


That's the prominent display on the left? The only one with white dots? Mine always seems to default to the 4th dot (I think), stepping on the accelerator moves it up and I get two dots, etc. I'm not so attuned to that gauge yet. Haven't noticed it moving down to, for example, 3 dots very often.

planet4ever wrote:Now, as to what cwerdna said about GOM: You didn't use that term, and his reference may be puzzling you. But you did say, "We almost never charge to more than 80-85% and never let it drop to less than 30%." If you got your car in January I have to assume it is a 2012 model, not a 2013 model. The 2012 does not have any gauge that tells you percent of charge. So, like cwerdna, my guess is that you are referring to that big number on the dash that Nissan calls "Distance to Empty" and we call "GuessOMeter" or "GOM". It is only very vaguely related to charge, and it is truly a guess being made by a computer (I would say a badly programmed computer) as to where you are going to drive and how you are going to behave in the future. Please ignore it.
You do have a "gas gauge"; it's those 12 blue and white bars surrounding the GOM. Ray


You're right - it's a new 2012 SL. Reading this forum has taught me what the GOM is, and I understand its shortcomings. To me it's only a predictor of how many miles we might get if we continue our at-the-moment driving patterns. What it does began to dawn on me a month into ownership when I took the freeway 20 miles to Santa Monica - it was slow and go the whole way, and when I started the GOM said 75 miles and when I arrived it said 73 miles. Yesterday I went to the store a mile away, left with 77, returned with 82. This has to mean I'm using regen braking well, and the Carwings site reading bears that out. It took about a month (sigh) but I finally discerned the difference between that "gas gauge" and the GOM. We have only a trickle charger, we have to charge the car on the street, so I can't just set the timer and forget it and leave it out all night. What I do is monitor it with the phone and disconnect when the charge gets to about 80%, as Nissan advises.


planet4ever wrote:
  • The first is "low battery" which we call LBW. The GOM starts flashing when you get down to this point. It's nothing to worry about - you are really about as far from empty as charging to 80% is from full.
  • The second is "very low battery" which we call VLBW. At this point the GOM "gives up" and just shows three dashes. You really are getting fairly close to empty at this point, and pushing much further might reduce the life of the battery.
  • The third is "Turtle". A reduced power message pops up on the dash and a picture of a turtle shows up there. This, my friend, is just about the end of the road. Find the closest safe place to stop, and call for help. Hopefully you will never see the turtle, but even if you do, know that Nissan has programmed the car to protect the battery. It will stop the car, likely within half a mile, and there will still be a few percentage points of charge remaining.

So the next time the GOM says 30 just grin at your wife and tell her this little beauty hasn't begun to show you what it can do. You haven't lived until you hear the mellifluous voice of the lady who tells you how low your battery is.Ray


I hope to never hear that voice. For one thing, we don't carry the white gun around with us - just too much trouble to coil up and squeeze into the case. We haven't gone very far in the Leaf at all - I'm impressed by people's 40-mile one-way commutes, including 1800' passes. My wife's commute is 20 miles roundtrip - she can arrive with almost as many miles on the GOM as when she left, but coming back she invariably loses 30-40. I'm guessing that's because (1) traffic is "lighter" (for LA) when she goes in the late morning and heavy when she returns at 6-7 pm; and (2) it's slight but gradual downhill about 500 feet going and the reverse returning. She's not OCD when it comes to the car like I am - she turns it on and forgets it, so she can drive all day with the defogger or AC on and not notice it. (We're also climate-control challenged - haven't even figured it out on the Prius and we've had that for 3 years). And every time she leaves the house, I watch her practically lay rubber going up our hill - she does the same with the Prius (our mpg with the Prius has never come close to 50 city - more like 40).

One more thing - a duh thing. It didn't occur to me to check the tire pressure on a new car. I finally did this morning - under-inflated by 4-5 pounds on all 4. :roll: I mean, I'll be happy if I manage to get all the quote coding right in this reply.

Thanks for your very detailed education and advice. I'm printing it out. Hope to remember where I put it. :)

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DaveEV
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Re: Unclear on regenerative braking

Sun Mar 24, 2013 11:03 am

I think the best way to think of how to drive efficiently, is to think of the best case scenario and then how to modify that scenario to fit into real life.

The best case scenario is traveling at a constant speed and then coasting to a stop at your destination.

Rate of acceleration to that constant speed does not matter too much - I would target between 10-25 kW as conditions allow.

Of course in real life, you have traffic lights and other traffic getting in the way.

When you know you have to stop, the best technique is to minimize your max speed and then coast to a stop.

If you need to slow down faster, it's better to use more regen during the higher speeds of your slow-down period and then coast to a stop. This throws less energy away towards wind resistance. The biggest drawback I've found to this technique in real life is that you often end up slowing down too much if you over-anticipate a red-light, for example.

wlegro
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Re: Unclear on regenerative braking

Sun Mar 24, 2013 11:21 am

garygid wrote:Using Regen, either from taking your foot off the accelerator
pedal, or by pressing the brake pedal, wastes some energy,
but does recover some energy, so it is less wasteful than
the mechanical braking, which wastes all the braking energy.

Sometimes it is necessary to apply braking to slow the car.
If possible, use Regen to slow the car, but when that is
unavailable or insufficient, the car applies the mechanical
brakes when you press the brake pedal.


I'm confused. Pressing the brake pedal in a Leaf engages regen braking, right? But you talk about mechanical braking (also by pressing the brake pedal) wasting all the braking energy.

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dgpcolorado
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Re: Unclear on regenerative braking

Sun Mar 24, 2013 3:01 pm

wlegro wrote:Well, along with terminology, I'm gauge-challenged. I try to watch everything and figure out what it is, but it's a little nerve-wracking in our traffic, and I haven't found the manual much help, though I'm also manual-challenged. Our other car is a Prius - same issues. Maybe I shouldn't even be driving these kinds of cars. :lol: If by the pie chart you mean the gauge in the upper left corner that adds or removes slices of pie depending how you're driving, I do watch that - it's the equivalent of the power column in the Prius, I think. I try to keep as many slices of the pie as possible. Come to think of it, that's how I eat pie, too. :)
No, the "energy screen" is in the center console; the menu is accessed by the "zero emissions" symbol button on the lower right of the console. The energy screen shows pie charts showing how much energy is being used by the car, displayed in kW. The main pie chart is very useful for learning to drive efficiently but, if it is a distraction in traffic, better to not use it until you are driving on mostly empty streets.
planet4ever wrote:The closest I come is moderating the accelerator so that only a single dot shows on the dash.Ray

That's the prominent display on the left? The only one with white dots? Mine always seems to default to the 4th dot (I think), stepping on the accelerator moves it up and I get two dots, etc. I'm not so attuned to that gauge yet. Haven't noticed it moving down to, for example, 3 dots very often...
Yes, the white dot display is a crude energy meter. It is useful to see how much regen is available (the circles to the left of the main dot) and how much power is available (the circles to the right of the main dot). Circles that are double are those that are available to use. If you charge to 100% you will see no double regen circles because the car has no regen capability if the battery is full, no surprise. To drive efficiently gentle acceleration is helpful, say one dot to the right of the main dot. This is easier to do in "Eco" because it easier to gently modulate your power. Also, with practice one can hold a "neutral" setting on the A pedal for coasting without regen. To drive efficiently coasting, no regen dots to the left of the main dot, is generally more efficient than regen braking.
...One more thing - a duh thing. It didn't occur to me to check the tire pressure on a new car. I finally did this morning - under-inflated by 4-5 pounds on all 4. :roll: I mean, I'll be happy if I manage to get all the quote coding right in this reply...
The book says 36 psi. Many of us use 40 psi (or more) to get better mileage. It also seems to help the stock tires wear better, although not everyone agrees with this assessment.
Last edited by dgpcolorado on Sun Mar 24, 2013 6:11 pm, edited 3 times in total.
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dgpcolorado
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Re: Unclear on regenerative braking

Sun Mar 24, 2013 3:21 pm

wlegro wrote:
garygid wrote:Using Regen, either from taking your foot off the accelerator pedal, or by pressing the brake pedal, wastes some energy,
but does recover some energy, so it is less wasteful than the mechanical braking, which wastes all the braking energy.

Sometimes it is necessary to apply braking to slow the car. If possible, use Regen to slow the car, but when that is unavailable or insufficient, the car applies the mechanical brakes when you press the brake pedal.

I'm confused. Pressing the brake pedal in a Leaf engages regen braking, right? But you talk about mechanical braking (also by pressing the brake pedal) wasting all the braking energy.
Yes, pressing the brake pedal engages the regen braking but it also engages the friction brakes, and it isn't clear when or how much. To avoid friction brakes entirely one would like to avoid the B pedal as much as possible. This can be done by using the regen on the A pedal. In D there is a slight amount of regen when you back off the A pedal entirely. In Eco there is a lot more regen when you back off the A pedal entirely. Except for coming to a complete stop at an intersection, or descending steep hills, it is often possible to drive just using the A pedal, especially in Eco with its greater regen braking.

It is also much easier to fine-tune one's speed in Eco, in my experience, because the pedal is mapped to constant power for a given pedal position, including zero—the equivalent of neutral—if you hold the pedal in that spot. Experimenting with single pedal driving is greatly helped by using the energy screen to learn about what is going on.

Some people prefer D because they are aggressive drivers and it feels more "peppy" (although full power is available in Eco also). Drivers trying to be efficient usually choose Eco for most situations.

In general, driving efficiently means learning to modulate your use of the A pedal and staying off the B pedal as much as possible. Inefficient drivers tend to use the A pedal as either "on" or "off": stomping it to accelerate and backing all the way off to slow. Using the A pedal gently both for accelerating or slowing will lead to more efficient driving.

Other than that, efficient driving is hard to explain and I think that you will find that time and practice will help you become better at it.
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Re: Unclear on regenerative braking

Sun Mar 24, 2013 3:49 pm

Nice write up dpcolorado, well put.

When I first read a post about not using the brake pedal, I thought it hyperbolic, someone making a rhetorical point. But as I learned to anticipate stops and slow downs, and when and by how much to ease off the accelerator, I have greatly reduced any use of the brake pedal.
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wlegro
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Re: Unclear on regenerative braking

Sun Mar 24, 2013 9:52 pm

Everybody's been really great about answering my questions, which I know have been asked before probably by almost everybody who's in their first months of Leafership and answered by everybody who's made an art of driving this car. I learned to drive at 12, and have done all the things with cars that guys normally do - rebuild engines, blow up the engine on the family wagon taking it to 110mph on the way to the orthodontist, driving up on the trunk of the guy in front of me who stopped suddenly to watch a girl in a bikini top and a sarong walking down the street (the same one I was watching but didn't stop for), add more STP than oil, install whizbang mufflers for 5 more hp on my old VW Bugs and vans, etc.

Now I'm having to learn to drive all over again. I mean, no STP? How cool is that?. I may have to up my dosage of anti-OCD med, but still...

This stuff about regen braking proved fascinating for me. I looked up my history on Carwings and was kind of amazed at what I found. I mentioned a trip to Santa Monica where I arrived with more GOM miles than I left with because it was slow-and-go on the 10 the whole way there, less so coming back. That day I drove 50 miles and got 12.5 m/kwh! Awesome. And here I used to hate slow-and-go, not to mention the 10. Despite what I said about my wife not noticing she's got the AC and the defroster on all day (that was a 1.9 m/kwh day), she's actually pretty good, thanks to Prius training. One day she drove 32 miles on city streets, including a climb up Laurel Canyon, over the hills and down into Burbank, then home on streets and through Griffith Park, which is basically a mountain. She managed 8 m/kwh that day. Another day with a similar route she got 11.5. But stuck on city streets, we're averaging 3.5 overall. Maybe closer attention to driving habits and higher tire pressure will help that. I wonder what AC will do once it starts getting warm. Besides being too hot to have the windows down on asphalt rivers running through concrete canyons, it's unhealthy to sit in this city traffic with the windows open. (I've been wondering about that - I'm also unclear on climate control, but I'm thinking that putting it on auto and setting a temp would be better than just hitting the AC button and forgetting it. You know, if we drove more than 7,000 miles a year on two cars combined, we might know more about all this stuff, but there it is...)

And we're having a lot of fun with this car - quiet, comfortable, smooth, excellent remedy for the piano-wire nerves you can get driving in Los Angeles. And my wife - she says every time she sees the car as she's walking toward it after work, she just loves it even more.

So thanks to all. I'm deeply appreciative. (Hey, maybe I could work all this stuff into a novel...can a Leaf explode in a ball of fire?) :lol:

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Re: Unclear on regenerative braking

Sun Mar 24, 2013 10:28 pm

ImageYou 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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Re: Unclear on regenerative braking

Mon Mar 25, 2013 2:22 am

wlegro wrote:One day she drove 32 miles on city streets, including a climb up Laurel Canyon, over the hills and down into Burbank, then home on streets and through Griffith Park, which is basically a mountain.


I lived in the equestrian district in Burbank when I worked at NBC studios from 1998-2000, I'd often take this trek through Griffith Park, by the zoo and golf course, to skip the parking lot also referred to as the "freeway". What a flashback. Thanks!

To clarify, when you take your foot off the accelerator, you are in regen mode. When you are in eco, you regen even more just by taking foot off accelerator (you can clearly "feel" this). When you hit the brake pedal, you regen even more, and you could also be using the disc brakes to stop. Like with the Prius, less brake pedal is better. You do not "coast" with your foot off the A pedal, you will need to push it slightly to keep from using regen (unless you shift to "N")
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Re: Unclear on regenerative braking

Mon Mar 25, 2013 4:56 am

Stanton wrote: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) 8-)


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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