Coasting in Neutral

[Gasaraki]

How do you shift into neutral at speed to coast when regen will slow you too fast?

Lightly step on the accelerator petal? Stop trying to drive like in an ICE car. You are just hurting your range by not regening.

 

[Kevy Baby]

I would prefer to have a quick shortcut button to simply disable regen until I hit the button again. Accelerator would still work but you could freely coast until you want to enable regen again.

What would be the purpose of that?

 

[Gasaraki]

It is true that freewheeling as much as possible is the most efficient. This is because of physics.

If you regen-brake, you are converting kinetic energy into heat and more charge in the battery. Some energy in this conversion will be lost as heat, because entropy.
If you actually-brake, you are converting kinetic energy into heat and, sometimes, sound. All of this energy is lost.

When you accelerate, you are converting battery charge into sound, heat, and kinetic energy.

Any time you convert energy from one medium to another, there are losses to heat. The most efficient means is to convert energy as infrequently as possible. The Neutral gear does this.

In hybrids, like a Prius, you can also freewheel without switching to Neutral by feathering the accelerator pedal so as to neither regen, nor accelerate. The same can be done with a Tesla; it's just harder to do so (if you're in standard regen mode) because the response curve on the pedal is so much steeper. That said, folks do this somewhat frequently (see the "rolling forward in Reverse!" threads).

Yes you are correct but by going in to N you are converting potential energy in to movement, great. But you then are moving too fast and have to step on the physical brake, which wastes ALL your energy when you try to slow down cause you can't regen. It more efficient to let the car regen than not.

 

[Gasaraki]

Now, if one needs to push down the accelerator to balance the regeneration that would mean you use some electricity

Not true. Pushing down on the accelerator does not automatically mean you are using energy. If the car is going down hill, the car knows that it doesn't need to use energy. Just look at your green/black bar under your speedometer. If it's green or right in the middle, it's not using any energy.

 

[DopeGhoti]

Yes you are correct but by going in to N you are converting potential energy in to movement, great. But you then are moving too fast and have to step on the physical brake, which wastes ALL your energy when you try to slow down cause you can't regen. It more efficient to let the car regen than not.

First, I like the username. Good series.

My post with which you disagreed was describing the physics of the situation, vis-a-vis most effecient use of energy in terms of reducing losses to entropy. Going "too fast" wasn't part of the point I was making. The question at hand was energy conservation irrespective of such corporeal concerns as speed limits and safe(r) practices. There are, as discussed upthread, myriad jurisdictions in which using the neutral gear (or "mode" if you will in transmissionless vehicles) is not legal, for reasons that are also discussed upthread.

 

[Gasaraki]

First, I like the username. Good series.

My post with which you disagreed was describing the physics of the situation, vis-a-vis most effecient use of energy in terms of reducing losses to entropy. Going "too fast" wasn't part of the point I was making. The question at hand was energy conservation irrespective of such corporeal concerns as speed limits and safe(r) practices. There are, as discussed upthread, myriad jurisdictions in which using the neutral gear (or "mode" if you will in transmissionless vehicles) is not legal, for reasons that are also discussed upthread.

I think the first sentence was me saying you are correct. How is that disagreeing?

 

[DopeGhoti]

I think the first sentence was me saying you are correct. How is that disagreeing?

You tell me.