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Did the Bolt ruin it for me? At least a little?

Discussion in 'Model S: Driving Dynamics' started by David29, May 12, 2017.

  1. David29

    David29 Member

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    Recently I drove a Chevy Bolt at an EV event. Just a short drive, a couple of miles on local roads, nothing dramatic.
    But the regenerative brakes were surprisingly powerful. They could and did bring the car to a complete stop. At the time, I questioned the salesman how they did it -- whether the car might actually be using energy from the battery, etc. (he did not seem to know much about the technical details). And I also questioned why the setup was so complicated. (As I recall, there were 2 or 3 levels of regenerative braking available, and you had to actuate the highest level of braking by using "paddles" on the steering wheel.) I also drove a Leaf and found it also had very good regen braking (but also felt it is too complicated to activate in the most effective setting).

    Then last weekend, I went to another EV event and let someone test drive my car. His own car is a Prius, and he had driven other EVs such as the Leaf and possibly the Bolt. He also commented that the Tesla regenerative brakes were not as effective as other cars. This led me to check to be sure I had the regen brakes on the Normal setting, which I do.

    But since these two events, I have been more aware of my Model S's regenerative braking, and find myself wondering why they are not more powerful. I never questioned them before! I do not know enough about the design of such systems to have a good answer if someone asks me why the Model S has less regen braking than these other Evs -- Does anyone else?

    I don't think there is anything wrong with my own, and they seem consistent with the handful of other Teslas I have driven. But my experience with the Leaf and Bolt make me wonder if Tesla could have done better.
     
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  2. Rockster

    Rockster Active Member

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    I've never driven any other car with regenerative braking but I do often find myself wishing that the Model S had a third, significantly more intense, setting.
     
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  3. phigment

    phigment Member

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    #3 phigment, May 12, 2017
    Last edited: May 12, 2017
    Tesla uses an inductive motor. They need to apply a current to create the magnetic field. This takes energy.

    Other brands use (rare earth) permanent magnets in their motors, thus the motor can bring the car to a complete stop.

    The benefit of the Tesla system is that they don't need to mine the rare earth metals for the permanent magnets, and they have more control over the magnetic field.

    More details can be found here: https://www.tesla.com/blog/induction-versus-dc-brushless-motors
     
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  4. AEdennis

    AEdennis Active Member

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    I used to drive an ActiveE and the BMW's regen is really strong compared to Tesla... however, Tesla's regen is plenty strong compared to many other brands.
     
  5. Petra

    Petra Member

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    As I recall, there's also some friction brake action being electronically blended in to provide a consistent experience when the vehicle isn't capable of full regen (or, at least, I recall this being the case for the i3).

    That aside, there's also another factor to consider when it comes to how the driver experiences regen: vehicle mass.

    The Model S can match or beat most other EVs when it comes to power produced during regenerative braking, but it won't feel as strong to the driver because the S is about 1000lb. heavier than other EVs. Put differently, 70kW regen acting on a 3580lb. Chevy Bolt will decelerate the car more quickly than 70kW regen acting on a 4410-5180lb.+ Model S. Both are capable of about the same level of regenerative braking from a power standpoint, one just has more mass (and, thus, more kinetic energy) to deal with.
     
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  6. McRat

    McRat Active Member

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    #6 McRat, May 12, 2017
    Last edited: May 12, 2017
    It's as complicated as you want.

    Hop in, hold brake, push the lit POWER button. Put car in D and drive it. All that 70kW max regen is there by using the brake pedal. You could see it on the energy gauge if so inclined. The car will creep at a stop just like every automatic transmission car. Other than no gears and quicker throttle response, you use it like every car. Well, they did something dumb to the shift IMO, but it does just operate like 'everything' does. I've been in some ICE cars that were more complicated (how to release the parking brake comes to mind, 10 different ways it seems).

    But what fun would THAT be????

    So instead, you shift from D to L. Now it's in One Foot Driving mode. It has no creep, and high amounts of braking through regen. Wait, you want MORE??? There is paddle on the left of the steering wheel, which maxes out the regen.

    So you can drive it like an ICE, or you can drive it like a hardcore Hypermiler. Or anywhere inbetween. Your choice.

    It feels so strong because it's about 1,000 lb less than the Model S yet has a peak of 70kW regen. Power to weight works both ways.
     
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  7. strider

    strider Active Member

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    IMO it's a combination of battery charge rate and what Tesla thinks is acceptable to their customers. Does anyone know how many kW the Bolt does in Regen? It's a MUCH smaller car so it will "take" less energy to slow it down at a higher rate than an S/X. Tesla may have determined that 60kW was the most they could push to the batteries across a wide operating margin (even when the batteries are hot, etc) and for very brief periods.

    Next is consumer preference. There's a reason that the max regen modes in the Leaf, Bolt, Volt, etc are difficult to activate. The manufacturers don't think most people will be comfortable with them working like that all the time. Tesla was an effective field of one 4 years ago when the S came out. Everyone else was doing blended regen on the brake pedal (ALL of them sucked back then. A few of the latest ones are good) so Tesla had to walk the line between effective and not being too weird.

    Now that there are more EVs and hybrids w/ regen out there and battery tech is improving, maybe Tesla will give us stronger settings in future vehicles.
     
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  8. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Well-Known Member

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    Hardcore hypermilers would want the car in "sail" mode where foot off is a full glide. Braking is for noobs. :p
     
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  9. McRat

    McRat Active Member

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    The Bolt is 35xx lbs and 70kW regen
    The Volt is 35xx lbs and 60kW regen

    But both are variable. If you like a lot of regen, you can have it. You like a little, you can have it. The only thing it won't do safely is 'freewheel', that is 0 kW regen. You pop into N for that.
     
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  10. Petra

    Petra Member

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    As I mentioned above, both the Bolt and Model S top out at about 70kW (highest I've logged from my S is about 68kW). So, yeah, it's a mass thing.
     
  11. McRat

    McRat Active Member

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    Yes, we know how to freewheel.

    But we also know that it's not as good as a trained foot. Sometimes coasting is not the perfect amount of speed reduction for the situation. You want just a little to catch the light. So you feather to 1-2kW regen or 4-5kW or whatever regen. Or 0 kW.
     
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  12. stopcrazypp

    stopcrazypp Well-Known Member

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    I'm pretty sure the max amounts are all around the same (it's 60kW for the Tesla). Just depends on how the algorithm works.

    Edit: as others pointed out the mass makes a difference in the amount of deceleration vs kW.
     
  13. ThisIsTrue

    ThisIsTrue Member

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  14. David29

    David29 Member

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    The customer preference angle was my suspicion as the main factor for having the separate range (L) and the paddle device. Avoid upsetting the first time driver too much, then let them add more as they get comfortable. That is in fact how the salesman introduced me to the car as we drove. Not sure if he knew I had a Tesla or not.
     
  15. Solarman004

    Solarman004 Member

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    I can't speak about the Bolt, but I do own a 2012 Leaf. I can definitely say that the MX has more powerful regen than the Leaf. And, since an update last year, the MX regen starts off more lightly, and gradually increases, which I like.
     
  16. Uncle Paul

    Uncle Paul Member

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    Extra regeneration is good for the agressive driver. An easy going, forward looking driver will find the Tesla system to provide over 90% of the braking needed for normal transportation.

    While nice for the driver, agressive regeneration braking is a pretty uncomfortable and irritating to the passengers. Most passengers really dislike agressive regeneration when used by the driver on a routine basis.

    Tesla has mentioned that their goal was to use regeneration for most casual braking, but still occasionally use the standard friction braking to keep all the mechanical bits in good working order.
     
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  17. Canuck

    Canuck Active Member

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    You sure lost me here. I've never driven a Bolt but I can't even feel the regen on my Leaf at all. I can watch it work with the circles filling up, but I can't feel it like my Tesla which grabs me.
     
  18. Cosmacelf

    Cosmacelf Active Member

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    So, yes, I think Tesla is missing a trick now by not having regen stop the car. It would be great if they added it, even if they had to use friction brakes for you.
     
  19. dgpcolorado

    dgpcolorado high altitude member

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    Hardcore hypermilers are welcome to try "sailing" on the hills I drive, which max out at a 14% grade with hairpin turns! (I do shift to neutral near the bottom of the hill and coast the next mile or so.)

    My only objection to Tesla's regen is that when the battery is cold regen is limited and when it is very cold I have to use friction brakes to descend that 14% grade with hairpin curves due to the lack of regen. Above a battery temperature of ~10ºC (50ºF) reduced regen isn't a problem on my hills. And having to gently apply the brakes to come to a full stop just isn't an issue for me.

    Since I drove a LEAF for many years I found the Tesla regen vastly superior in both strength and application. I particularly like the simplicity of having all the regen on the "go pedal" with the brakes left alone (the LEAF had blended regen on the brake pedal, which adds complexity).
     
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  20. MS16

    MS16 Member

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    In California, Chevy will bring a Bolt to your house or work for you to test drive. I might have to try it and see how the regen is.

    Chevy Test Drives
     

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