Variable Regen

[kerbe2705]

My understanding is that there are those who prefer to NOT use Adaptive Cruise Control when driving longer distances on highways and want to be able to “coast” at will.

My personal choice is to allow the vehicle to decide when it wants to coast and when it wants to regen to maintain a constant speed.

There may also be some Luddites in the EV community who either distrust or dislike the “feel” of regenerative braking and choose to rely solely on friction braking…

[RajGiandeep]

My EV experience with regen is a ’13 Leaf. Which doesn’t have very strong regen. Depending on the road. Sometimes I do put it in neutral to coast to extend my range instead of having to float the pedal just right.

I mentioned this on the previous forum. But would be nice to be able to switch to neutral or switch between regen (light, medium, heavy) easily while driving.

[JRWiley]

Raj, does “put it in neutral” in an EV mean turning off regen completely? I was under the impression that EVs don’t have transmissions. Clearly, I really know very little about all of this.

[hans-roes]

While EVs generally speaking, there are excpetions, don’t have a classic gearbox with multiple gears, they do have a single speed reduction gear and when you place them in neutral. Placing an EV in neutral can be done in many ways. But don’t forget that you need the ability to push the car with as little friction from the motor as possible in case you brake down and need to move the vehicle by hand. So it would not surprise me if some EVs actually have the option to decouple that gear from the motor.

[jaron-harding]

The hubless motors on the EV do not have any gears and the only neutral would be no regen. It is interesting that the only friction will be in the bearings of the wheel.

[RajGiandeep]

On my Nissan Leaf there is Park, neutral, 2 variants of drive mode with more or less regen. You can float the pedal just right and coast pretty well. But nothing like putting it in true neutral.

[Riley]

on icy roads the car can lose control when the regenerative breaking causes the tires to lose traction.

[llewellyn-evans]

Great point. Same thing with some kinds of mud.

[RajGiandeep]

Forgot about that since my regen is weak compared to newer evs. Wonder if the traction control can alter the regen in cases of wheel slip/slide.

[kerbe2705]

Wait, WHAT? This is, quite simply, not a function of regenerative braking: ANY braking system without traction control enabled can lose control on ice.

[llewellyn-evans]

Turning off regen in an Aptera will be a totally different experience to any other EV because the drag coefficient is so low. She is going to keep going much faster than any PA (Pre-Aptera) EV. Down hill with no regen will be like being on a street luge.

[jaron-harding]

neat idea, see who can set the longest coasting record 🙂

[Biker]

For now, it seems Lightyear has it:

Lightyear 0 Proves Another Advantage of Sharp Aerodynamics: Coasting Gets You Further (autoevolution.com)

[Jeff]

Idk if the coasting will really be much different, given how much lighter the Aptera is supposed to be than other EVs.

For a rough example: if, at a given speed, the Aptera has about half as much wind+rolling resistance (force) as a Model 3, but the Aptera also weighs about half as much, then the resulting coasting behavior (deceleration rate) should be similar.

[harry-parker]

👍 Yes, let’s hear it for Physics: F = ma (Force equals mass times acceleration). So a = F/m .

[hans-roes]

I’ve been driving an Ioniq now for a little over 2 years and I play with my regen settings on every drive.

Contrary to popular believe, full regen is not the most economical way to drive. When regenerating power, you lose a lot of it with all the conversions that you have to make. Ultimately, you will only be able to put about a third of the power back to work for you, losing about two thirds in the regeneration. So, when driving on a highway or in free flowing traffic, I turn off regeneration, that way if I need to cruise a little, or just lose a little bit of my speed (e.g. approaching a lower speed limit with no traffic behind me), I can just let friction take the speed away and that is more efficient than actually slowing down faster with regen and putting some energy back in the battery,

When in heavy traffic, I want heavy regen. I’ll be accelerating and decelerating a lot and having lots of regen means I have to use the brake pedal a lot less. And when in normal traffic, I’ll take light regen, that way, when I lift off from the accelerator, I get some engine braking and the behavior is similar to ICE cars which is also more comfortable for the cars behind me.

I do know not every EV driver likes to play around with those settings and plenty of drivers leave them at the default of light regen because that’s what they are used to. But selecting the right mode for the circumstances will bring you an actual benefit. And I do hope that Aptera makes it possible for drivers to select their level of regen on the go as more and more EVs are getting this capability. Hyundai/Kia were the first I think, but now we also see them for example with VAG cars.

[JRWiley]

Viewing one of the Aptera videos, we were shown on the control screen that using full regen would increase range. Would it be the case that if I were driving in free flowing traffic on a highway with no regen I could actually gain even better range? Does the no regen mode have the feel of an ice car being put in neutral?

[hans-roes]

Without seeing any explenation from Aptera where they get those numbers from or how the behavior of the car changes, it’s difficult to say where it comes from. If, for example, the physical brakes engage from the moment you press the brake pedal and therefore use less regen, then it is correct that enabling regen could offer you more range. And it is possible that an average driver, who does not like to change the setting, will benefit more from having it turned on than off.

But as has been shown multiple times already, driving with regen on is not always the best option. A couple of years ago, when I was slowly getting more and more into EVs, I came across a video on YouTube about the just launched LEAF 2.zero. Nissan had invited a bunch of press and influencers to a nice and warm location (can’t remember where) and at one point gave them a challenge. Drive down from the mountain to a town and they added a small contest to it. Winner would be the person with the lowest consumption. 2 teams arrived with equal consumption Bjorn, if it was him, had done the run with regen off, the car in D-mode, no e-Pedal, no AC, …

[kerbe2705]

Yes – coasting without regen feels exactly like coasting in neutral.

[Skeptible]

I am going to translate “cruise” to mean “maintain speed” and “coast” to mean “slow down at a slow rate”. If I am misinterpreting, then ignore my comment. I drive a Bolt which I keep in the max regen mode at all times. I love one pedal driving. I also use cruise control when traffic allows. This means that there is a very slight bit of regen happening on only the very steepest hill on my route. When not in cruise control, when I want to maintain speed, I keep my foot steady. When I want to slow down gradually, I lift my foot just a little bit. Whether the regen kicks in or not is determined by how quickly I want to slow down.

I did once ride as a passenger with someone that would push down on the gas until they were going faster than the speed they wanted to maintain, and then would take their foot off until they were going slower than they wanted to go. Then repeat. Keeping my mouth shut about it drove me nuts.

[kevin-bradbury]

” Keeping my mouth shut about it drove me nuts.”

LOL! I couldn’t. When a friend of mine was driving like that, I had to ask, “this truck has cruise control that works, doesn’t it?”

[john-malcom]

Regen is one of the features of EVs that us older ICE drivers need to adjust to. The Aptera engineers have provided the opportunity to select various levels of regen to suit our preferences based on our driving circumstances. We have the opportunity to experiment to find the right settings or to select a setting and adjust to it in all driving conditions.

I think, that as Aptera learns lessons for the Beta prototypes, and subsequent refinements to production, and releases that information to us, we will have a good appreciation to the capabilities and range of regen available in production.

A have a neighbor with a Bolt. He likes the one pedal driving that requires strong regen. I drive a Model3. I like the light regen as I am an old Ice driver and can’t break the ICE driving habit. Maybe I need a 12 Point Program, ICE Drivers Anonymous …..

[trollfaced-hudagmail-com]

less reliance on regen and more reliance on maintaining momentum is better for both efficiency and battery life.

especially for long drives, to prevent user from needing to stay on pedal position to maintain momentum: screen should require pedal to be around a certain position in order for cruise control to be disengaged, or even better a mechanical locker on pedal or electric motor actuating pedal, that way maintaining speed after disengaging is lot easier. mechanical version is like chain and pulleys and a door sliding lock type thing.

[harry-parker]

Hi my_discord_number_is_0328,

I’m guessing you don’t live or drive around where there are big or steep hills like I do. EVs need regen to maintain speed on the downhills and extra acceleration (more pedal) on the uphills to maintain speed. In that case, a fixed pedal position works well if you’re hypermiling and want to go up hills decelerating and downhills accelerating, annoying the people behind you, … until you exceed the speed limit greatly. Then the policeman laying in wait at the bottom of the hill will want to have a word with you.

I’ve found that my Chevy Volt’s normal light regen setting works well in hilly country or city settings. I’ll switch to heavy regen on steep downhills if the light regen with cruise control can’t maintain my car’s speed. I’ll only switch to Neutral when the road is empty for a few seconds when I need to use the seldom used real brakes to clean the rust off of the brake disks. (They get rusty and corroded from lack of use in wet climates.)

[george-hughes]

The regen you get when cruising, whether heavy or light, is just a tool you can use to control speed. If you control speed wisely, you can maximize regeneration and often do so using one-pedal driving.

First, heavy regen is useful for driving where there is a lot of acceleration and slowing, as in running through hilly curves on a secondary road or just plugging along in heavy traffic.

Certainly most of us remember driving an ICE car down a long steep hill. In those circumstances, truck drivers often shift to a lower gear to avoid over-heating the brakes.

We all know that it takes energy to go up hill and one of the advantages of an EV is that it will generate energy on the way down which ICE vehicles can’t.

Regen feels like a lower gear going down hill and is strong enough to slow the car when going down hill on most hills.

In the Spark EV I drive, there is negligible difference between high and low regen, as measured by KW generated, when going down mild hills at a speed set by cruise control. When going down steeper hills, the normal regen found in “D” on the Spark, will be overwhelmed by gravity and it will accelerate. However, in “L”, my EV is capable maintaining the speed set in cruise with an increase in the KW generated number on steeper hills.

The instrument display of the Spark allows the display of +/- KW in real time in one of its screen options. This provides a precise instrument to gauge your power use.

For instance there is about a six-mile run from the western part of the county to the center that is largely downhill. Of course it includes up-hill portions but on average, you lose 150-200 ft. of elevation going west to east. I set the car’s cruise at 55 at the first hill crest. The motor is generating at about 4-5 kw as I head to the valley. As I head up the next hill, I limit my kw power to no more than 20 kw. This costs me maybe three mph by the time I hit the crest of the next hill where the decline is significantly larger. I add enough KW (no more than 30kw) to regain my speed which results regen in “L” rising to 20-25KW in following 40-60 seconds of regen. The next rise is relatively mild and I let the cruise maintain 55 mph as the KW output to power the motor remains under 15kw … and so on with adjustments made with the cruise controls.

The point is by the time I’ve reached town, my GOM range has increased 2-3 miles. In another 8 mile run to town on some back roads, I can get the display to report consuming energy at the rate of 6.8 miles/kw using the same technique.

Bottom line, maximizing regen is a ‘game’ you can play provided you have the instrumentation. I do hope the Aptera will have real-time numeric display of power in both acceleration and regeneration. This allows you to gamify driving with hand controls.

The funniest take-away of this ‘game’ is that folks in ICE vehicles – particularly Semi’s – tend to exceed the speed limit down hill to make it easier to get up the next hill.

By my use of gravity to maximize regen, the ICE vehicle driver has to put on the brakes to maintain 55 wasting that energy heat. The funny part is when I maintain 55 uphill they are usually left behind.

Besides the game, I use maximum regen to maximize my one-pedal experience.

[Fran]

Regen is only “more efficient” for those who drive like a normal ICE driver, who maintain speed until they get to a turn or stop and then use their mechanical brakes to slow down or stop. Efficient driving is NOT using the brakes at all, coasting from way out while approaching a turn or stop. Regen brakes are useful for these efficient drivers when a car pulls out in front of you or a traffic light changes while you are approaching at speed and expected to get there before it turns. Regen process is not totally efficient, maybe 90% to turn the kinetic energy into electricity and 80% to put that electricity into the battery. Then to get that energy back to moving the car again, 90% to get electricity out of the battery and 90% the use the motors to get the car moving. If these estimates are correct (they are not) the total efficiency of the whole process is 90% times 80% times 90% times 90% or .9 x .8 x .9 x .9 = .5832 or 58.32%, where if you just coasted and planned your stops so you never used the brakes, the efficiency would remain at around 90%.

[Greek]

I constantly go from drive to neutral if I know I will be stopping or at least slowing down until the next traffic signal…I don’t do it always because I believe switching gears also takes energy away from the battery.

Another thing in terms of efficiency. If you have a somewhat full battery, your regen is not as effective, as it limits the amount of energy it wants to receive to protect the battery. So stopping distances become longer.

[geoff-dale]

I found it did not take long to get used to one pedal driving in a Model 3 on the higher regen setting. Just as you modulate your acceleration you do the same decelerating including coasting. No need to keep changing regen levels or selecting neutral just use your right foot, hardly ever touch the brake . Very satisfying comfortable and economical way to drive!

[jonah-jorgenson]

I have the same experience driving my Model 3. Simple process without having to change things and eventually wear them out. No need for complexity😁

[william-manewal]

I found the same with a Chevy Bolt EV. I loaned it to my daughter who initially said she felt comfortable only without regen (D mode). But within one day she was in L mode, with regen, and loved it. I do find that having the ability to engage more regen with the steering wheel paddle is useful on almost every drive, for when a driver pulls out unexpectedly or when I need to adjust my deceleration required for a changing stop light.

• This reply was modified 5 months ago by  William Manewal.