Stoaty's Guide to Energy Efficient Driving of the Leaf

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Stoaty

Well-known member
Joined
Jun 18, 2010
Messages
4,490
Location
West Los Angeles
For those like me who want to conserve as much energy as possible I offer my recipe--tested over 2,000 miles--for getting the highest Mile per KWh from the Leaf. I have a lifetime average of 5.8 miles per KWh (dash reading) and a daily commute that involves 1300 feet of elevation gain, with 28 miles on freeway and 12 miles on city streets. Over 100,000 miles, I figure that I will save 7,800 KWh compared to an average of 4.0 miles per KWh. That's a lot more than turning off a few lights. At 15 cents per KWh (for LA DWP Green Power) that comes out to almost $1200. Note that the environmental considerations of energy conservation are an order of magnitude more important to me than price.

There are two main principles to follow in order to achieve this mileage:

1) The slower you drive the better, since wind resistance increases with the square of the velocity. Never drive faster than 55 MPH, except by coasting down a hill.
2) To the maximum extent possible, don't use energy from the battery that can't be dissipated by coasting, hills, or wind resistance (rather than from regen or braking). Once that energy is gone, the most you can get back is 30% from regen. EDIT: from the regen thread, it appears regen is probably more like 70%: http://www.mynissanleaf.com/viewtopic.php?f=31&t=5509" onclick="window.open(this.href);return false;

How Stoaty does this in practice:

1) Treat the Leaf like a video game, learning how to maximize your efficiency as you practice
2) Use EV Mode with Energy Screen showing on the Navigator screen
3) Charge to 80% when feasible (I alway do this), since you will have regen available right away (if needed) instead of waiting until the battery discharges significantly
4) Maximum speed in the city is usually 25-35 MPH; maximum speed on the freeway is 52 MPH (traffic permitting, which it often doesn't), except when coasting down a hill. Use right lane of freeway when traffic is significantly faster.
5) Accelerate gently from stops (usually up to 10 KW, occasionally up to 20 KW)
6) Look ahead at the speed of traffic and the next 1-2 stoplights. Note whether the lights are "stale" (have been green for a while and likely to change soon) so you can anticipate when you are likely to need to slow down or stop. Use just enough power so that you can end up coasting up to stopped traffic, or using a minimal amount of regen to slow when necessary.
7) Once you are up to cruising speed, feather the accelerator so that you are either coasting (zero on energy screen) or using just a slight amount of power to keep speed constant
8) Don't let off the accelerator enough to invoke regen unless you need to slow down. This just wastes power unnecessarily.
9) When you need to use regen, use it over a long enough distance that you don't max out on regen and end up needing to apply the brakes also
10) Use the brakes only when the above techniques have failed to slow you enough or you have to stop (absent an unexpected stops, brakes should usually only be needed below 10 MPH).
11) EDIT: after further testing, I now use regen on long downhill stretches (like Sepulveda Pass on 405 freeway) and keep my speed at 50-52 MPH. This resulted in a 5% increase in efficiency on my regular 47 mile commute (6.1 -> 6.4 miles/KWh on energy screen center console)
12) Don't be concerned if people race by you, and occasionally--and rudely--honk. If you are driving with maximum efficiency you will likely see them stopped very soon, either in a freeway slowdown, or waiting at a light. I often pass the people who raced up to the light in another lane and are waiting there, stopped.
13) Stoaty has rarely used AC, partly because it isn't that hot, and partly because when it got up to 95 degrees (low humidity) he used that as an opportunity to acclimate to the heat--which paid off on a recent backpacking trip. Depending on the temperature, humidity, your heat tolerance, etc. this may not work for you.

It really isn't that hard to learn, and soon becomes second nature. Driving this way is fun and relaxing, because you are never in a hurry to make the next light and don't spend very much time stopped. There also isn't much of a time penalty--at least for me--because my commute has gone from 32 minutes one way to 37 minutes one way.

Any other eco-obsessive drivers out there? :cool:
 
My goal is to be at the absolute bottom of the list in Carwings, drive as hard and as fast as I can, use maximum A/C, and always arrive home with as low a battery as possible! :lol:

Stoaty said:
Any other eco-obsessive drivers out there? :cool:
 
Ignore tailgaters, eventually they will get the hint.

How to Hypermile:

http://www.cleanmpg.com/forums/showthread.php?t=1510" onclick="window.open(this.href);return false;
 
TomT said:
My goal is to be at the absolute bottom of the list in Carwings, drive as hard and as fast as I can, use maximum A/C, and always arrive home with as low a battery as possible! :lol:

Stoaty said:
Any other eco-obsessive drivers out there? :cool:


I agree, I never drive slower than the flow of traffic. There are a few haters that no matter how fast you drive your LEAF, they think you're going slow. I had one guy in an SUV trying to drive up my tailpipe (if I had one) in a 45 zone...I was driving 52-53. He ended up passing on a double yellow and gave me the meanest look I've ever seen. Later I passed him in the carpool lane on the freeway and didn't take too kindly to that either....ended up wanting to try to force me off the road for a fight.....be careful out there!

My suggestion, if you have the range to drive like "a normal car", do it...even if you need to charge to 100%.
 
I find that you can glide at 30 or 40 or 50 mph the same way. The question is what is the optimum speed for driving? Somebody said the Nissan mentioned that 38 mph is the optimum speed for the Leaf. It that true?
 
I am driving allot in the HOV lanes in LA. What I invariably find for my 7 - 10 miles in the HOV lanes is that I can go around 55-60. The car in front of me often gets far ahead, but invariably on this section of the 405 I catch up to him/her as the road always clogs up.
There just isnt a 70mph average out there during the commute.
That is not to say that folks behind me arent stacking up or, as sometimes happens, passing me, but I almost and I do me pretty much almost always, catch up to them.

I know some of them are not cool with this, but maybe they will learn.
:roll:
yeah, right.
 
Once that energy is gone, the most you can get back is 30% from regen.
30% efficiency for regen seem quite low to me. Like in this other thread http://www.mynissanleaf.com/viewtopic.php?f=31&t=5509 I would tend to think it's close to 80% based on what we know about the efficency of the components. Also if the efficiency of regen was really 30%, where do the other 70% go? 21kW is a lot of power to dissipate and I've never noticed any of the LEAF's components in the engine compartment get even close to warm after driving it and using regen.

But I agree with the reasonning : It's better to avoid regen if you can so that the kinetic energy of the car is used for fighting friction and wind resistance rather than recharging the battery.

I actually wish there was a mode where regen is turned off.
 
Volusiano said:
I find that you can glide at 30 or 40 or 50 mph the same way. The question is what is the optimum speed for driving? Somebody said the Nissan mentioned that 38 mph is the optimum speed for the Leaf. It that true?
According to testing reported on MNL, the optimum speed (from an energy efficiency standpoint) is 12.5 MPH:

http://www.mynissanleaf.com/viewtopic.php?f=31&t=4295" onclick="window.open(this.href);return false;
 
ericsf said:
I actually wish there was a mode where regen is turned off.
You can always switch to Neutral, can't you? Or if it's not a long enough period to want to be in neutral, you just feather the gas pedal such that your energy meter show 0 consumed and 0 regen.
 
Eric,

I am pretty sure I saw that 30% number on MNL. When I looked up Prius regen efficiency, best guesses were 30-50%. If it is better than that, I would like to see a reference. Don't know the real answer, but doubt the 80%. That would be phenomenal.
 
Volusiano said:
You can always switch to Neutral, can't you? Or if it's not a long enough period to want to be in neutral, you just feather the gas pedal such that your energy meter show 0 consumed and 0 regen.
Yes, you can just switch to neutral. I actually do this going downhill on the 405 from the top of Sepulveda Pass. Going South, I can coast for about 5 miles at 55 MPH or greater, and feathering the accelerator pedal is way too much trouble. I switch into D when I get to about 62 MPH so I can recoup some of the energy. The North side is steeper, so I switch to D and just leave it there once I get to 60 MPH. Still, I would like to have a button to toggle the regen in ECO mode on and off.
 
It is commendable that Stoaty and others are seeking to do all they can for the good of the environment shared by all humanity. There are plenty of occasions on which I practice those hypermiling recommendations, mainly to extend the range of the LEAF on our longer drives.

But I'm not convinced that impeding the flow of traffic is worthwhile just for the sake of saving some kWh. I'm not just saying this because of "haters" out there. At this point, we are the ambassadors for a new way of driving, using electricity. Some of us, like my family with our Christian-themed license plate frames, use our cars to promote other causes as well. Why leave people with a bad taste? The LEAF can be a zippy car. I figure that, range permitting, we might as well show other drivers the joy of instant torque and near-silent acceleration! By encouraging EV adoption, this seems likely to have greater overall environmental benefits.

Also, I would believe 80% regen efficiency, if you subtract aerodynamic and friction losses first, before arriving at a figure for the amount of kinetic energy available to be captured.
 
I am pretty sure I saw that 30% number on MNL
Don't believe everything you read on the internet :lol:

Seriously, I do agree 80% would be the maximum efficiency one could expect. Do you have a thread link where this was discussed?

Also I am trying to think of a practical way to measure this and put this to rest. Any idea?
 
Here's what I posted in another thread:
abasile said:
On our 5000' descent, we average probably 45 mph over 16 miles, and pick up very roughly 1.5 bars of regen (call it 2.5kWh). Assume the potential energy is 1.37kWh/1000', or 6.8kWh total. At 0.2kWh/mile, we use 3.2kWh to go the 16 miles [on flat ground, which gives us the aero+friction losses]. That leaves 3.4kWh to be consumed by braking. Assuming only regen braking and no friction braking, that would give us a regen efficiency of very roughly 2.5kWh/3.4kWh, or 74%. This is where we need an SOC gauge for more precision!
 
Stoaty said:
8) Don't let off the accelerator enough to invoke regen unless you need to slow down. This just wastes power unnecessarily.
I follow the same maxims when maximizing my range though I usually drive the freeways at 60mph and accelerate at 20KW. #8 has been the hardest for me to get used to.
 
My coast down technique is to slowly let off the gas pedal and as the power nears zero, I pull it into neutral. As I approach a stop, I put it in D or ECO again, depending on how poorly I judged the stop. If I over do it, it's right back to Neutral, and then D or ECO again until stopped.
 
abasile said:
But I'm not convinced that impeding the flow of traffic is worthwhile just for the sake of saving some kWh.
I agree 100% and never impede the flow of traffic. However, here is my definition of impeding the flow of traffic, and what is not impeding the flow of traffic (although others may not like it):

Impeding the flow of traffic - driving significantly slower than the flow of traffic on a 2 lane road. Example: driving 30 MPH up the Mount Baldy Road, and refusing to use turnouts so other cars can pass.

Not impeding the flow of traffic:

1) Driving 52 MPH in the right hand lane of the freeway. Those who want to go faster can use the other 3 lanes. I do this all the time, and often find that I have to either slow down or temporarily go into the next lane to pass a truck going slower than I am (on the way up to the Sepulveda Pass).

2) Driving 25 MPH in a 35 MPH zone when there is a stop light 50-100 yards away that is red. The flow of traffic is being impeded--by the stop light, not by me. Some prefer to race up to the light and eagerly wait for it to change; I do not.

3) Slowing to 35-40 MPH on the freeway when cars are stopped 150 yards in front of me. The stopped cars are impeding the flow of traffic, not me. As a matter of fact, if I can avoid stopping by going a bit slower, I will be helping to break up the rolling wave of stopped cars that is likely to ripple down the freeway.

Note that I have run into a few drivers (not that many, actually) who think it is their God-given right to race up to stopped traffic in #2 and #3 scenarios, and that I am impeding the flow of traffic. Very occasionally I run into someone who thinks that driving 52 MPH in the right hand lane is a personal affront to them, and they show their displeasure with various gestures. Neither of these happen very often, and I have noticed more people than in the past who seem to realize that it is the traffic holding them up, not a single "bad" car.
 
Volusiano said:
The question is what is the optimum speed for driving? Somebody said the Nissan mentioned that 38 mph is the optimum speed for the Leaf. It that true?

No, 38mph isn't the best. I drove a 15 mile loop @ 15mph without A/C in over 100* heat and achieved over 9.1m/kW h. Every few miles or so the efficiency increased, so maybe I could have hit 9.5 after 30 miles which X21=200 miles on a 100% charge!
Tony, I believe, claims 12.5mph is the optium speed and since I didn't go lower than 15, he could be right, but he would have to achieve at least 9.1 and he didn't, so I'm doubting the lower speed.
 
LEAFfan said:
Tony, I believe, claims 12.5mph is the optium speed and since I didn't go lower than 15, he could be right, but he would have to achieve at least 9.1 and he didn't, so I'm doubting the lower speed.


I used the hyper accurate technique of driving 15mph, then 10mph, noting no significant difference, and proclaiming the middle, 12.5mph.
 
Stoaty said:
For those like me who want to conserve as much energy as possible I offer my recipe--tested over 2,000 miles--for getting the highest Mile per KWh from the Leaf. I have a lifetime average of 5.8 miles per KWh (dash reading)
5) Accelerate gently from stops (usually up to 10 KW, occasionally up to 20 KW)
7) Once you are up to cruising speed, feather the accelerator so that you are either coasting (zero on energy screen) or using just a slight amount of power to keep speed constant
13) Stoaty has rarely used AC, partly because it isn't that hot, and partly because when it got up to 95 degrees (low humidity) he used that as an opportunity to acclimate to the heat--which paid off on a recent backpacking trip. Depending on the temperature, humidity, your heat tolerance, etc. this may not work for you.
Any other eco-obsessive drivers out there? :cool:

13. I do most of those techniques too, but in 110-115 humidified (monsoon season) heat (we broke an all time record of over 34 days [could soon be 36 of 110 or higher]), I sometimes use the A/C. Otherwise, my m/kW h are in the 6's.
5. If no traffic, I can accelerate up to speed fairly fast (takes practice) using neutral bubbles, but if someone is behind me, I can do it much faster using only ONE bubble. It isn't necessary to use two or 20kW.
7. To stay in the neutral bubble and to keep your speed constant once up to speed, you can use the CC by going one mph over what you want, then push down quickly on the button and it will put you in the neutral bubble.
And I agree wholeheartedly with you about the not impeding traffic explanation. I can drive this way without impeding any traffic also. Even though I have PVs and the driving is basically free, I still like to drive this way for the reasons you have stated. :mrgreen:
 
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