Hypermilers: Don't use Neutral to coast to a stop

[jclemens]

Ok, is there a conclusion to this thread? a consensus? if so, please update the first post, it still is not totally clear. right now I am interpreting it to mean that it is not beneficial to coast from full drive speed down to a complete stop while in N (not safe either because that is a very long distance going very slowly.)

I have developed the habit of always only sliding into neutral when I am coming to a stop, but only after regen stops working, I do this to over-ride the creep.
is this good or bad? (in terms of best energy savings)

 

[TimLee]

Ok, is there a conclusion to this thread? a consensus? if so, please update the first post, it still is not totally clear. right now I am interpreting it to mean that it is not beneficial to coast from full drive speed down to a complete stop while in N (not safe either because that is a very long distance going very slowly.)

I have developed the habit of always only sliding into neutral when I am coming to a stop, but only after regen stops working, I do this to over-ride the creep.
is this good or bad? (in terms of best energy savings)

This is the summary, just a few posts bacK:

The reasoning why I say Neutral is not the most efficient mode to coast in is while the car is moving, the inverter draws 1-2kW of power even when in Neutral.

I've confirmed this using the Leaf Battery App. Coasting down a long hill at 55mph was drawing ~5amps (*400v -> 2000w - same ballpark).

The only way to get to zero energy in or out of the battery is to keep it in D or ECO and modulate the throttle.

I played around with it. Yes, I could get the battery draw down to 0A, however I had to use some regeneration to do so. If I actually modulated the throttle to have no accel or regen (as determined by the Leaf's energy screen on the nav), then I was seeing the same 5a draw.

Therefore, I don't think it matters if you use Neutral or not - the inverter is going to draw that extra current anyway. You can counteract that draw with some regen, but then you're slowing yourself down a bit to do so.

It doesn't really matter which way you minimize power use whether coasting or feathering the throttle to hold nominal zero power use. Power draw will be the same 5 amps. But coasting is easier, as you know it will be 5 amps. The other way feathering the throttle you have to get it just right.
Of course coasting only works well for just the right grade. And coasting is not appropriate under some conditions due to traffic and safety considerations.

I haven't tried neutral to avoid the built in creep following the loss of regeneration. If you try that, don't try the quick neutral by putting it in Reverse. Below 7 mph it will try to go into reverse and bring the LEAF to a bad abrupt halt. Not good for the LEAF.

 

[TickTock]

To summarize. If you are coming to a stoplight, there is a very small amount of additional energy that can be saved by not using neutral and allowing regen to power the inverter overhead instead of drawing from the battery. You will stop sooner and once stopped this load goes to zero so that is how the energy is saved (spend more time stopped at the light at zero power than you would if you managed to perfectly coast in N to the stop). However, I think there is a consensus that it is difficult to do better with the throttle (<2kW but >0kW draw) and the benefit is so small and specific that only the most extreme HM-er would bother.

 

[EVDRIVER]

Summary. Drive the car and stop worrying about small gains in efficiency. There are people that have switches on their EVSE to turn them off each night to save a few pennies a month and they spend hundreds on the switch to do it not to mention all the wasted time. Let's get some perspective. There is also a point of costing were you are wasting energy to wind drag vs gains regen. Drive the car and forget about it :roll:

If you really are worried about efficiency then buy my hood mounted fan generators, they ship with anxiety pills included.

 

[derkraut]

Summary. Drive the car and stop worrying about small gains in efficiency. There are people that have switches on their EVSE to turn them off each night to save a few pennies a month and they spend hundreds on the switch to do it not to mention all the wasted time. Let's get some perspective. There is also a point of costing were you are wasting energy to wind drag vs gains regen. Drive the car and forget about it :roll:

If you really are worried about efficiency then buy my hood mounted fan generators, they ship with anxiety pills included.

+1 EVDRIVER, you hit the nail on the head again; plus, you are one funny dude. :lol:

 

[dgpcolorado]

Summary. Drive the car and stop worrying about small gains in efficiency. There are people that have switches on their EVSE to turn them off each night to save a few pennies a month and they spend hundreds on the switch to do it not to mention all the wasted time. Let's get some perspective. There is also a point of costing were you are wasting energy to wind drag vs gains regen. Drive the car and forget about it :roll:

If you really are worried about efficiency then buy my hood mounted fan generators, they ship with anxiety pills included.

Then again, there are those of us who find this stuff fun (I know: what a novel concept!). And those who push the range, especially with degraded batteries, can benefit from driving efficiently. Learning how to hypermile can be a useful skill when pushing the range of the car.

If you only drive twenty miles a day, you're right: drive the car and don't worry about it. However, where I live, being able to drive efficiently is a big deal; it's not as if there are any charge stations if I guess wrong about my range.

[Yes, I know that your posts are usually not to be taken seriously. But sometimes snide gets old.]

 

[mkjayakumar]

I will say this again.

- Use 'N" anytime you see a stop light and when you know that you will have to reduce your speed. But you need to shift to N fairly early, and believe me Leaf in 'N' rolls amazingly well for a fairly long distance with a very gradual and minimal speed reduction. It rolls much better than an ICE vehicle.

- Avoid 'regen' like a plague all the time, except when you have to step on the brakes and you would rather get some energy back instead of wasting them as heat.

- I am not willing to buy the argument that an EV (specifically Leaf) is unsafe while in 'N'. The car exactly feels and behaves the same way when the battery is full and regen is turned off.

- I never coast to a completely stop. At some point you know that it is best to engage the brakes to stop. Then shift back to 'D' and press the brakes.

Coasting on 'N, is the easiest hypermiling technique you can use to gain the maximum efficiency and increase in range. It is not the pennies that drive me to use 'N', it is the necessity to drive 70 miles everyday on a highly degraded battery.

And lastly shifting to 'N' and back is piece of cake in Leaf. The hockey puck design is amazing. The single most thing I love in my Leaf.

 

[thankyouOB]

ah, i remember when folks were also telling us to drive the car like we stole it and not to worry about anything.
floor it and watch it zip.
but then that was the spring and summer of 2011.

 

[babynuke]

You have those for sale??? The generators...not the pills.

If you really are worried about efficiency then buy my hood mounted fan generators, they ship with anxiety pills included.

 

[DaveinOlyWA]

Summary. Drive the car and stop worrying about small gains in efficiency. There are people that have switches on their EVSE to turn them off each night to save a few pennies a month and they spend hundreds on the switch to do it not to mention all the wasted time. Let's get some perspective. There is also a point of costing were you are wasting energy to wind drag vs gains regen. Drive the car and forget about it :roll:

If you really are worried about efficiency then buy my hood mounted fan generators, they ship with anxiety pills included.

good point but as ALWAYS, too much of a good thing is bad and that applies to everything.

this is information. now what you do with the information is what gets one in "trouble". moderation and common sense applies to all things.

information is good, PERIOD. its only our actions that can cloud that statement

 

[LEAFfan]

I will say this again.

- Use 'N" anytime you see a stop light and when you know that you will have to reduce your speed. But you need to shift to N fairly early, and believe me Leaf in 'N' rolls amazingly well for a fairly long distance with a very gradual and minimal speed reduction. It rolls much better than an ICE vehicle.

- Avoid 'regen' like a plague all the time, except when you have to step on the brakes and you would rather get some energy back instead of wasting them as heat.

- I am not willing to buy the argument that an EV (specifically Leaf) is unsafe while in 'N'. The car exactly feels and behaves the same way when the battery is full and regen is turned off.

- I never coast to a completely stop. At some point you know that it is best to engage the brakes to stop. Then shift back to 'D' and press the brakes.

Coasting on 'N, is the easiest hypermiling technique you can use to gain the maximum efficiency and increase in range. It is not the pennies that drive me to use 'N', it is the necessity to drive 70 miles everyday on a highly degraded battery.

And lastly shifting to 'N' and back is piece of cake in Leaf. The hockey puck design is amazing. The single most thing I love in my Leaf.

That was well said. I would add using ECO before using regen/friction brakes and shift to R to get N faster than 7mph. Also, for the 2013, using ECO B regen braking can keep you from using the brakes at all.