Turning off regen and power limiting for increased range

[dmsail]

You can turn off regen by popping it into neutral. As pointed out by someone above, it is risky but with practice and paying attention you can use it safely. There are times when it is more efficient coasting instead of regenerating but it is more risky and is technically illegal in some cases. This is similar to the "pulse and glide" that people do in the Prius also using Neutral.

 

[Cowby]

I totally understand the OP's delimma and sometimes wish the same thing (as a fellow hard core stick shift driver back in the days). Even tho the manufacturer and defensive driving schools never wants us to leave the car in neatral we often did/do it in instances like exiting the freeway (trying to time it as much as possible). Two things as a result: 1) This yielded the best mpg possible for ice's, and 2) we got to give our go/gas foot a little respite. I fear only hard core stick shift hyperrmilers really understand this POV tho.

 

[hmmm]

As I understand,
break - action to destroy something or take a rest
brake - action to slow down or as a noun, describing a slow down device.

Your English is broke.

 

[XP90D]

No vehicle manufacturer recommends that their vehicles be put into neutral to coast for increased economy.

Even with manual transmissions, it is less safe to shift into neutral than to remain in gear at speed on a highway.

You want to be able to instantly have throttle control, as well as to use engine braking to remove speed on long downhills. (reduces chances of brake fade)

Not sure your statement is correct.....


Porsche with their PDK transmission automatically does this very thing. It will automatically coast in neutral when appropriate at highway speed to conserve energy as needed it is seamless and intelligent. Surprised Tesla doesn't utilize a similar technology.

"coasting function becomes available where the situation allows. The engine is decoupled from the transmission to avoid deceleration caused by engine braking. In this way, optimum use is made of the vehicle’s momentum, enabling it to coast for longer distances."

 

[vandacca]

I find myself often driving 100-110 KM//h following traffic in the middle lane, and with TACC the car is constantly going into regen mode (even with distance setting to 7, I have AP2 in case AP1 is smoother). If I had coast mode, I would simply vary the distance between me and the car in front to avoid braking (thanks mrElbe), and avoid needing to transfer my precious mechanical energy into battery storage and loosing a good percentage of it to the various losses. Regen is great if you need to brake, but coasting is always better than regen...

I can't speak for what is happening to you with AP2 because I have AP1 and I haven't experienced what you're reporting.

However, coasting and regen do not perform the same task. If your vehicle is going into "regen", it's because it thinks it needs to slow down (equivalent to braking). Maybe the AP2 software is too twitchy right now and it's not working efficiently. If that's the case, learning to feather the accelerator pedal is your only option.

I strongly advise not going into Neutral while driving a Tesla. Coming from a stick shift ICE, I used to drop into Neutral all the time. It was a simple process and it was extremely easy to tell (via feel, sound, etc.) when you were engaged and disengaged without having to take your eyes off the road.

With the Tesla, I would be scared to do this, as I'm never sure if the shift (into or out of neutral) succeeded or not without having to look down, change focus and search for the drive indicator. I'm not even sure it's possible to put it into neutral at speed, since normally you have to depress the brake to shift. Admittedly, I haven't tried it and I'd be afraid to try it because I don't think I can reliably and quickly shift between N and D in an emergency situation.

 

[JHWJR]

No vehicle manufacturer recommends that their vehicles be put into neutral to coast for increased economy.

Of course they do. On automatic transmissions, when you take your foot off the pedal, the car coasts. There is no meaningful engine braking like one experiences in a standard shift or when regenerating. The OP is saying he wants to emulate that coasting, believing that he will go further, more efficiently, than "engine braking" or "regenerating."

And my intuition supports the OP's supposition/experimentation. Out west, where you can drive 100 miles on amazingly flat land and never see another car and never brake for incredible distances, I think going into regen mode (thus slowing down the car and converting only some of the kinetic energy into battery reserve and the losing some when accelerating), while far more efficient than actually braking, is not likely as efficient as just "coasting" and FAR easier than trying to perfectly "feather," even if it were the energy equivalent.

Regenerating is a tremendous advantage over braking because braking converts your kinetic energy to heat, where it is wasted. Regenerative braking instead converts a good portion of that energy (perhaps 80%) to battery charge for use later. But coasting doesn't force the car to slow at all. Nothing is lost to heat or chemical storage. So why make it harder to achieve that? I like this idea for settings in which it actually makes sense, which I think we would all agree is not around town.

 

[ABC2D]

Out west, where you can drive 100 miles on amazingly flat land and never see another car and never brake for incredible distances, I think going into regen mode (thus slowing down the car and converting only some of the kinetic energy into battery reserve and the losing some when accelerating), while far more efficient than actually braking, is not likely as efficient as just "coasting"

Are you saying that you will use less energy for 100 miles going accelerate-coast-accelerate-coast-accelerate-coast-accelerate-coast (for 100 miles) than just go at constant speed (for 100 miles with no braking)?

 

[xkwizit]

Regen is great for city driving (stop and go) but not for highway/long distance driving when you rarely need breaks. Put it this way, the only thing better than capturing mechanical energy and putting 50-75% of it back in the battery is leaving it as mechanical energy. That's why i really want to find a way to disable regen completely for long trips.

With ICE cars, i can understand the benefits of coasting especially when gas is $4/gallon. But with Tesla, I don't see what OP will achieve by coasting - a few more, maybe 20 miles, from a full battery before you get to the next supercharger or your home? If it's supercharger, what do you gain by reaching there with 20 more miles in the "tank" and if you are charging at home, in about $5 you can charge an empty battery so a few more miles may be worth less than two cents of saving.

Of course, if you are running out of juice to reach the supercharger coasting may come in handy but that kind of situation should be an exception and not your regular driving.

 

[vandacca]

IMHO, coasting is irrelevant to this whole discussion. The important question is why is the Tesla going into "regen" (assuming there is no need to slow down) at all? I suspect it's just an inefficient algorithm and it would be best solved by Tesla with a future update.

Next time I'm on the highway (I have a 11 hour trip planned this weekend), I'll play around with it and see if AP1 has a similar issue.

 

[ThosEM]

Regen is effectively OFF when you set your cruise control to the speed you want to drive and leave it there.

It will come on to prevent you from accelerating downhill, saving the energy that would otherwise go into increased aerodynamic drag.

 

[brucet999]

No vehicle manufacturer recommends that their vehicles be put into neutral to coast for increased economy.

What you say is true about neutral, but most automatic transmissions, like our Lexus, actually coast when you take your foot off the accelerator in "Drive" gear. Only when you have shifted into 2nd, or L, or "Tiptronic" mode, or whatever they call it, do you get any engine braking. Even back in the 40s, the overdrive on some manual transmissions allowed coasting without any engine braking.

 

[brucet999]

I find myself often driving 100-110 KM//h following traffic in the middle lane, and with TACC the car is constantly going into regen mode (even with distance setting to 7, I have AP2 in case AP1 is smoother). If I had coast mode, I would simply vary the distance between me and the car in front to avoid braking (thanks mrElbe), and avoid needing to transfer my precious mechanical energy into battery storage and loosing a good percentage of it to the various losses. Regen is great if you need to brake, but coasting is always better than regen...

I think you are missing the point a bit about using TACC. It never regens on a flat open road, only in traffic or to control speed when going downhill.

TACC in traffic is not good at anticipating when it needs to slow, so it goes full speed until it gets within its set distance behind the car ahead, then regens to slow down. It is not as smart that way as you are. But if it had no regen, it would not be smart enough to take off power and coast earlier either. It would simply go full speed until it reached its set following distance and then apply friction brakes to slow, thus wasting more of your "precious mechanical energy".

My advice; learn how to feather the accelerator pedal for smoothest ride experience and lowest Wh/kilometer.

 

[ig_epower]

On the concept of feathering, there is a kickpoint in the accelerator that switches the car from acceleration to regen/decel. If there was a highway range mode available, that could entail the programming of a wider transition from accel to regen. Think of it as a wider deadpoint setting or a sluggish accelerator. In cruising mode, the driver may opt for a more sluggish accelerator for better range than a more performance-oriented mode where the transition from accel to regen is much tighter. Luckily this concept is relatively easy to implement in software.

 

[JHWJR]

Are you saying that you will use less energy for 100 miles going accelerate-coast-accelerate-coast-accelerate-coast-accelerate-coast (for 100 miles) than just go at constant speed (for 100 miles with no braking)?

No, I think that those would be equivalent. Having had only limited opportunity to drive a Tesla while waiting for mine to arrive, I do recall there being little, little room between acceleration and regeneration. I am not sure that it is as easy to walk the line between acceleration and regeneration (while staying out of regeneration entirely) is as some here suggest. And I'm not sure what is gained by regeneration on those long, flat drives, but it's easy to see that coasting -- rather than the forced slow down of regeneration -- provides a benefit. So, again, my intuition is that there is something to be gained by turning regeneration off.

It is suggested above that the benefit would be minimal. OK. So be it. But there are threads here where folks suggest folding up the mirrors in an attempt to get better mileage too, so getting a few extra miles is a consideration for some, if only for the sport of it.

 

[brucet999]

Are you saying that you will use less energy for 100 miles going accelerate-coast-accelerate-coast-accelerate-coast-accelerate-coast (for 100 miles) than just go at constant speed (for 100 miles with no braking)?

Your choice of words sent my mind back almost half a century to a ski trip with a college friend. We were driving late at night through the Utah desert, trading off driving and sleeping, but I remember not being able to sleep while he drove because he could not seem to maintain a steady pace, but alternated every few seconds between slight acceleration and deceleration.
Maybe some people just can't keep a steady position of the accelerator pedal. For them, regen would exacerbate the problem.

 

[FSKT]

What you're asking for does not make sense. If you need to slow down, regen is the best way to slow down. If you had some "magical" coast mode, that would force you to use the brakes to slow down, wasting that kinetic energy into heat. You do not want this "coast" mode, it will do the opposite of what you think.

But . . . what I really want is to be able to coast when I can, and then when I need to slow down, use as much regen as possible, versus brake pads. The problem I'm discovering with my M3 (and I believe all Tesla's to date) is that you can't do this - you can't have both. When Regen is on "standard" on my M3 (which is "high" regen), the regen is on, all the time, always. I can't coast, at all. But in the other "Low" setting, I regen is less, and it is possible to coast a bit, BUT when I apply the brakes, NO additional regen is added to slow down the car.

The best would be both. No regen (coasting) when you let off the accelerator pedal, but ALL regen when you brake, or a lot at least. Then, when it's more efficient to coast - which it is sometimes - you can do that. But when you need to slow down, at all, when you hit the brake pedal then regen is used, completely or mostly (blended).

What I'm seeing from looking at posts about this subject is that the main reason perhaps Tesla does not have such a set up is because the "blending" of regen with pads to slow a car down is a technology that is spotty and complicated and jerky/uneven. Not a good "braking experience" in other words, which would reduce the fun of driving the vehicle noticeably. Indeed, in my Fiat 500e, the which did use 100% regen when you hit the brakes, until you got to 8mph where the pads would then take over, had pretty "grabby" and uneven braking.

OK, but Tesla is really good at this stuff. It's clearly better than Fiat in all things EV, let's be honest. So, it's likely that if Tesla applied itself to this blended/regen braking thing they'd make a really great system, I'd think, where you could coast when that's most efficient, but when you hit the brakes, you'd be regen'ing big time. Here's to hoping they'll do that.

 

[vandacca]

The thing I like about regen braking is that it's a super smooth transition. When it comes to regen and braking (both regen braking and brake pads) is that you want to keep things as simple as possible. This is arguably one of the most important safety aspects of a car, so you don't want to over-complicate it. I like how Tesla has done it.

Having said all that, with some practice you can learn to "coast". When you let your foot off the accelerator, you can learn to sense the sweet spot between the motor disengaging and regen beginning. Probably not something you want to do for a long period of time, but at the moment, that's all you can do with a Tesla.

I think it's in Tesla's DNA to keep things very simple for the average user, so I doubt you'll get super advanced options or features in any of their cars.

 

[animorph]

Coasting is easy enough to approximate if you don't let off the accelerator all the way. you can check the energy meter to see how close you can get to zero power/zero regen.

 

[Tslacg]

With the newer sw versions I think they've done this for highway coasting. The standard regen now reacts more like low regen for the first few seconds then is gradual. For the most part this helps coast when needed and is also awesome to avoid the bobbing effect of lifting off the accelerator to coast. It's a subtle but welcome change.

 

[mxnym]

With the newer sw versions I think they've done this for highway coasting. The standard regen now reacts more like low regen for the first few seconds then is gradual. For the most part this helps coast when needed and is also awesome to avoid the bobbing effect of lifting off the accelerator to coast. It's a subtle but welcome change.

Actually, I don't like this change, because I was able to control it with the pedal and get better efficiency before the change. Now you have to try to time when you release the pedal for stops instead of using the pedal to control the speed. When the change first occurred, it seemed like barely touching the brake pedal would kick the regen up faster than the few second delay, which was just as good, but in later updates, that went away.

I totally hear where OP is coming from, nothing wrong with wanting to be as efficient as safely possible. I use TACC even though I have a hilly drive and it's doing a lot of unnecessary regen on those hills, but one of the things I hated about my most recent automatic transmission ICE vehicle was how much it engine braked (because my previous automatic ICE vehicles all coasted nicely). It couldn't maintain speed with its TACC, though, it was constantly back and forth between acceleration and engine braking on hills, it was so annoying that I threw it into neutral all the time (several times on my daily commute). I think switching between N and D in the Model S and Model X without looking at the IC is easy and safe, regardless of archaic laws really meant for manual transmissions. Personally, I'm not usually compelled to do it in spite of the loss of range the unnecessary regen is causing, but I understand the desire for an option that takes away the "necessity."