One-Pedal Driving in Rivians???

Discussion in 'Rivian General Discussions' started by Lil'O Annie, Mar 4, 2019.

  1. Lil'O Annie

    Lil'O Annie Active Member

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    One of the many things I LOVE about my Chevy Bolt EV is the regen one-pedal driving. I rarely use the brakes at all. I'd say I drive without using the brakes 99.5% of the time. Love that feature!! Not all EV's have that option and I would miss it if I don't have it. I only use the brakes for emergency stops. Will one-pedal driving be a feature in the Rivians??
     
  2. RefugeEV

    RefugeEV Active Member

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    It sure will! Here's a great explanation for Rivian's one-pedal driving setup.

    Full-stop one-pedal regen braking
    Like an increasing number of electric cars, the new Rivian vehicles can not only regenerate power back into the battery to help slow down but can quickly bring the vehicle to a full stop and hold it there without use of the traditional brake pedal — even on an incline.

    The BMW i3, Chevrolet Bolt EV, 2018 Nissan LEAF, and the new Hyundai Kona Electric can all do this.

    On the other hand, so far, Tesla vehicles require use of the brake pedal to quickly come to a full stop or hold the vehicle in place.

    Like the Bolt EV and 2018 LEAF, Rivian supports driver configurable options to control the intensity and behavior of regenerative braking that occurs on the accelerator pedal.

    Regenerative braking is ineffective at very slow speeds (the last several mph) so car makers that support full-stop one-pedal braking either blend in friction braking (in the 2018 Nissan LEAF) or they use active motor torque using a small amount of power from the battery as the Bolt EV and Rivian do. Similar strategies are used to hold a car on an incline.

    Charles Sanderson, Rivian’s VP of Development & Integration, says they can hold the vehicle at up to a steep 20 percent road grade just using active motor torque.

    Like almost all other electric and hybrid cars, Rivian also initially uses regenerative braking as the traditional brake pedal is pushed but transition to friction braking as the need for anti-speed increases as the driver pushes down farther on the brake pedal.

    Like many other car makers, Rivian is using Bosch’s iBooster brake system. Even Tesla has used this system since they introduced partially-automated driving features into the Model S although Tesla has programmed it to use only friction braking when the driver steps on the pedal, presumably to guarantee the highest level of consistent braking feel.
     
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  3. Lil'O Annie

    Lil'O Annie Active Member

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    :clap: HOORAY!!!:like: Thanks for the info RefugeEV!! I like one-pedal driving so much that it is almost an absolute requirement for me.
     
  4. Ricky35

    Ricky35 Member

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    Interesting... so the Rivian vehicles will be able to come to a complete stop in non-emergency situations without ever putting your foot on the brake pedal? So it's like driving an insanely fast golf cart!
     
  5. Lil'O Annie

    Lil'O Annie Active Member

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    I hope it's true. Sounds like it is and if you haven't experienced one pedal driving you'll get use to it quickly and never want to go back!!! :clap: Driving a car without it is painful now. Driving any ICE is painful now. EV's are just better...period!
     
  6. CappyJax

    CappyJax Well-Known Member

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    Sounds like it would be more efficient to use the brake pedal to bring the Rivian to a stop at low speeds. If you let the vehicle stop on its own, it is using power to slow it the last few MPH and hold the vehicle stationary.
     
  7. ACDC

    ACDC Member

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    Perhaps, but the gain in efficiency is probably pretty negligible unless you're in stop and go traffic for hours?

    One pedal driving I can get used to. But I have concerns about how I'll feel about brake regen. I don't like the feeling of strong regenerative braking where as soon as you let off the pedal it feels like hard braking. I know the strength of it will be configurable by the driver but I also don't want to fall way short of the potential quoted battery range if I turn off brake regeneration or set it to minimal level.

    How much does brake regen actually contribute to an EV's mileage range?
     
  8. sdTom

    sdTom Member

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    i know on my plugin vehicle in normal mode, you dont notice it. in sport mode it brings on the regen hard.. actually charges the battery vs simply maintain/drop in level
     
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  9. Lil'O Annie

    Lil'O Annie Active Member

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    Hard regen in my Bolt is something I got use to very quickly. It feels very much like normal braking and you learn to use the power pedal to moderate the level of regen when driving around town. I honestly greatly miss not having that regen when I get into an ICE vehicle. I think it really does improve mileage in my Bolt, too. I live out in the country, so 95% of my driving is long distance, but I've noticed when I'm in town, doing a lot of stop and go, there are times it appears that I'm not using any power with an occasional "gain" of more potential miles, but that is probably due to the guess-o-meter adjusting miles due to slower speeds. For me, the advantage of one-pedal driving is more a driving experience aspect than a major gain in energy recovery.
     
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  10. CappyJax

    CappyJax Well-Known Member

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    If think we can assume that regen efficiency is greatest when set to the lowest setting just like the slowest charging of the battery is most efficient. So, planning ahead and letting the vehicle coast as much as possible will produce the greatest efficiency. However, the difference between highest regen and lowest regen setting probably won't be more than a few percent. Also, on many EV's. the first few % of brake pedal application starts with regeneration before the hydraulic brakes are applied. So, you can increase the regeneration that way as well by feathering the brake pedal.
     
  11. Electric Rivilution

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    Is this true? If so crap I've always had my X's brake regeneration on the highest setting thinking it'd recapture more energy compared to lower settings.
     
  12. sdTom

    sdTom Member

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    yeah my experience supports high regen = high recovered energy. its less wasted to brake heat. its not like charging efficiency best at slow as regen is still not as strong of energy as being plugged into wall.. i.e., strong regen < outlet power
     
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  13. CappyJax

    CappyJax Well-Known Member

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    High regen versus low regen, not high regen vs using the hydraulic brakes. If you have an EV on low regen, then you are slowing down at a slower rate and therefore producing a lower amount of power to the battery, but for a longer time. This means lower amperage which means less loss to heat.

    High regen could be substantial. If the deceleration is half as pronounced as full power acceleration, then you could just divide the total power by two to get the wH going to the battery. For example, the Chevy bolt has 150 kW motor. Therefore, in high regen the power to the battery could be around 75 kW which is substantial. I don't know how close this is, but I have driven a Bolt, and that is what I guesstimated to be the regenerative power. Now, we do know that superchargers are less efficient at charging a battery than a house charger, and a 50 Amp 220V house charger is only 11 kW.

    Just FYI, you may have heard of Tesla buying Maxwell. Maxwell makes capacitors that can absorb larges amounts of power very quickly, and return that power very quickly. This likely means they are intending to have some capacitors to store the regen energy, because it does so very efficiency. Upwards of 98%. This would also put less stress on the battery during quick accelerations.

    Most people don't realize this, but at full power, most electric cars have less than 15 minutes of power. The Rivian has 600 kWs of power, so even with a 180kWh battery, you only have 18 minutes of energy to outrun the cops:) But actually, running a Lithium ion battery at nearly 4C for much longer than maybe a minute would cause it to overheat.
     
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