Active E coming to four U.S. regions next year:
http://wheels.blogs.nytimes.com/2010/09/27/bmw-activee-electric-car-headed-for-u-s-trial/?hpw
http://wheels.blogs.nytimes.com/2010/09/27/bmw-activee-electric-car-headed-for-u-s-trial/?hpw
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BMW Active E
- Thread starter dpeilow
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- Electric Vehicles
JRP3
Hyperactive Member
My car has a neutral pedal position that allows coasting, though I'd like to increase it, I assumed all EV's had the same. Does the Roadster not have a coast position on the A pedal?
I am not sure what they are talking about. With the RangerEV, if you take your foot off both pedals it goes into regen mode and starts slowing. (There are two virtual "gears" so you can have two levels of max regen to pick.) With talk of "coasting", I take that to mean some "mode" where you take your foot completely off the accelerator pedal and it doesn't do any regen. The Roadster doesn't do that unless the regen is disabled intentionally due to "pack nearly full", or extreme temperatures. It sounds like (but I can't be totally sure) that the ActiveE goes into a coast-mode if you let off both pedals, but then if you tap the brake pedal it turns on regen? With any EV (including Roadster, Ranger, etc.) you can "pseudo-coast" by holding the accelerator pedal right at the level where power applied is just enough to keep you going at your current speed. A more true "coast" would be to go into a neutral gear, but I don't think Ranger, Roadster, or ActiveE ever disengage the eMotor from the wheels, so "coasting" is just a state where it lets the eMotor "freewheel" without doing regen. Unless the inverter gives it a little power there would be some drag just spinning the motor. So, anyways, I think there would be some more detailed questions that need to get answered to understand exactly what they are talking about.
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JRP3
Hyperactive Member
With my car there is a spot in the A pedal throw where you are neither applying power nor getting regen, you are just coasting. If you lift off further you get regen, which you can vary by lifting off more to increase or applying slight pedal to decrease, even more pedal to coast, then on to acceleration. The coasting zone is fairly narrow on my car which is why I want to get into the controller and reprogram it to give me a slightly larger coasting range.
Is that really a "coast region", or just happens to be the "stasis point" where you are putting just enough power through the controller to keep you going the same speed?
To me a "coast mode" means you let off of the accelerator pedal completely but don't get any regen so keep going roughly the same speed but slow down slowly just based on wind resistance and rolling resistance.
I guess another attribute of something people might think of as coasting is a state where the vehicle will start to speed up on its own if you start to head down a steep hill. That would differ from say a fixed cruise control setting where it tries to maintain an exact speed regardless of grade.
To me a "coast mode" means you let off of the accelerator pedal completely but don't get any regen so keep going roughly the same speed but slow down slowly just based on wind resistance and rolling resistance.
I guess another attribute of something people might think of as coasting is a state where the vehicle will start to speed up on its own if you start to head down a steep hill. That would differ from say a fixed cruise control setting where it tries to maintain an exact speed regardless of grade.
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JRP3
Hyperactive Member
It's a true coast mode. My amp gauge reads zero at that point, nothing in, nothing out, and you can feel yourself coasting as well. You will speed up on a downhill. I would think any vehicle would have a throttle position that would take no current from the pack nor put current back into the pack, though some controllers may have that position so narrowly mapped that it would be difficult to hold that spot.
On the RangerEV it feels like the inverter is always 'doing something' if I just try to modulate the accelerator pedal. But it also has an 'old school gear selector', and if I put that in the 'N' position only then do I feel like it is really coasting.
JRP3
Hyperactive Member
JRP3
Hyperactive Member
I thought I read that the Roadster has a neutral pedal position. Too bad there isn't some place where Roadster owners could comment on such things....guys?
The article description makes regen sound like an "on/off" thing with your foot off the pedal, but I suspect it is modulated linearly by pedal position, as in my car, for smoother operation and better control.
The article description makes regen sound like an "on/off" thing with your foot off the pedal, but I suspect it is modulated linearly by pedal position, as in my car, for smoother operation and better control.
SByer
'08 #383
I don't know that the 'neutral' position is actually fixed, but in practice, with instant torque feedback (and the slight auditory feedback of the gear box), in all practicality, it's pretty darned trivial to find and keep near-coasting neutral. I really, really, really would not want any 'clever' (hah!) software algorithm getting in the way of that.
JRP3
Hyperactive Member
For my car I would like the neutral area on the pedal to be a bit larger to make it easier to coast, since that is the most efficient means of travel.
Interesting! I've never felt like I needed a neutral position. I just adjust my foot based on how fast I want to go or to adjust my approach to the car in front of me -- I generally don't even think about acceleration/deceleration -- I just adjust my right foot based on what I'm observing. I rather like that style. The adjustment in the near-zero acceleration area is subtle, so I don't feel like I have to try really hard to maintain proper speed.
JRP3
Hyperactive Member
Frankly if you aren't concerned with getting as much range as possible it's not much of an issue. With a Roadster sized pack a couple extra points of efficiency don't matter most of the time, and maximizing efficiency isn't a fun way to drive a sports car anyway.
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