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Stoaty's Guide to Energy Efficient Driving of the Leaf

Posted: Fri Sep 02, 2011 3:01 pm
by Stoaty
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? 8-)

Re: Stoaty's Guide to Energy Efficient Driving of the Leaf

Posted: Fri Sep 02, 2011 3:07 pm
by TomT
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 wrote:Any other eco-obsessive drivers out there? 8-)

Re: Stoaty's Guide to Energy Efficient Driving of the Leaf

Posted: Fri Sep 02, 2011 3:13 pm
by Herm
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;

Re: Stoaty's Guide to Energy Efficient Driving of the Leaf

Posted: Fri Sep 02, 2011 3:23 pm
by Ready2plugin
TomT wrote: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 wrote:Any other eco-obsessive drivers out there? 8-)

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%.

Re: Stoaty's Guide to Energy Efficient Driving of the Leaf

Posted: Fri Sep 02, 2011 3:59 pm
by Volusiano
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?

Re: Stoaty's Guide to Energy Efficient Driving of the Leaf

Posted: Fri Sep 02, 2011 4:01 pm
by thankyouOB
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.

Re: Stoaty's Guide to Energy Efficient Driving of the Leaf

Posted: Fri Sep 02, 2011 4:56 pm
by ericsf
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.

Re: Stoaty's Guide to Energy Efficient Driving of the Leaf

Posted: Fri Sep 02, 2011 4:59 pm
by Stoaty
Volusiano wrote: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;

Re: Stoaty's Guide to Energy Efficient Driving of the Leaf

Posted: Fri Sep 02, 2011 5:01 pm
by Volusiano
ericsf wrote: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.

Re: Stoaty's Guide to Energy Efficient Driving of the Leaf

Posted: Fri Sep 02, 2011 5:03 pm
by Stoaty
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.