5 ms·

Interesting about the acceleration and braking UX... that experience is exactly what makes electric passenger cars feel sporty and responsive, but I can see why

Interesting about the acceleration and braking UX... that experience is exactly what makes electric passenger cars feel sporty and responsive, but I can see why you don't want that for municipal buses. Then again, the "gas pedal" is basically a skeuomorphism dating back to when it mechanically opened up a gas valve... it's all drive by wire, so, "fix it in software"?

Moter8 8y ago
Yep. As it is all controlled by software, this is being done today already. Drove a Volkswagen E-Up. It had an Eco and an Eco+ Mode. Those seemed to just limit the acceleration, and for a bus this seems mandatory.
- cptskippy 8y ago
  The Nissan Leaf defaults to Eco mode and the pedal is very unresponsive. Click Eco Mode off and it'll give you whiplash.
- usrusr 8y ago
  What makes limited acceleration more economic? Are there efficiency losses that are dependent on the time it takes to convert x joule from electrochemical storage to inertia?
  - sawjet 8y ago
    Probably just changes the pedal mapping.
  - bluGill 8y ago
    It is more about the shift points in the transmission. Your engine is most efficient at around 90% throttle and "low" rpm. Your car is more fuel efficient are highway speeds then city street speeds (aerodynamic factors are insignificant at low speeds). The result is that engineers can trade acceleration for efficiency by changing the shift points, and you don't realize that the throttle is nearly wide open since the car isn't accelerating very hard at the low rpms. Of course the engineers who design eco mode probably know more about how to do this than I do. I know they mess with shift points, it wouldn't surprise me if they did other things too.
    - cmrdporcupine 8y ago
      EVs have no 'shift points' or changing gear ratios.
      - bluGill 8y ago
        Maybe or maybe not. Some EVs have a transmission - while it isn't strictly required (which is why others do not) for best acceleration you need one. If there is a transmission this is a shift point. Of course EVs have completely different operating parameters. The rest of my post was respect to a internal combustion engine.
        cmrdporcupine 8y ago
        Some EVs have a transmission, yes. My Volt has a planetary gear set in order to share traction with the ICE. But that's not a pure EV. But what they don't generally have, unless they are conversions from ICE cars, is changing gear ratios. Torque is mostly constant across all RPMs in an EV, so there's not really a need for one.
  - petre 8y ago
    You also kill the batteries in shorter amount time if you do not limit the acceleration. The habbit of pressing the accelaration to the bottom will drain lots of power from the battery. It also encourages reckless/sporty driving. Best way to do this is on passenger cars is to have an eco/sport switch. On a passenger bus or truck you don't need a sport switch, since those vehicles are meant to be driven responsibily.
  - davidgould 8y ago
    Yes. Resistive losses in the motor and inverter are proportional to the current squared (I^2). Accelerating hard requires more current so 2x acceleration incurs 4x resistive loss. It's not a huge effect in most applications, but it does make a difference.
Obi_Juan_Kenobi 8y ago
Tesla introduced a "chill" driving mode for this very reason. It makes acceleration and braking (regen) much smoother and many owners speak highly of it.
- Fnoord 8y ago
  I was taught to drive like that in The Netherlands by my driving instructor. It is much safer (especially with deliberate bumps to slow you down in a neighbourhood where children play), saves you fuel, and it saves you your brakes. It does cost you a little bit time and this can add up if it means you miss a traffic light due to that but it could also mean that you still get a green light. So in the end, the loss is very little to nothing.
caf 8y ago
On gasoline (as opposed to diesel) engines, it actually used to mechanically open a butterfly valve that controlled the air intake (the throttle).

Moter8 8y ago

Yep. As it is all controlled by software, this is being done today already. Drove a Volkswagen E-Up. It had an Eco and an Eco+ Mode. Those seemed to just limit the acceleration, and for a bus this seems mandatory.

cptskippy 8y ago
The Nissan Leaf defaults to Eco mode and the pedal is very unresponsive. Click Eco Mode off and it'll give you whiplash.
usrusr 8y ago
What makes limited acceleration more economic? Are there efficiency losses that are dependent on the time it takes to convert x joule from electrochemical storage to inertia?
- sawjet 8y ago
  Probably just changes the pedal mapping.
- bluGill 8y ago
  It is more about the shift points in the transmission. Your engine is most efficient at around 90% throttle and "low" rpm. Your car is more fuel efficient are highway speeds then city street speeds (aerodynamic factors are insignificant at low speeds). The result is that engineers can trade acceleration for efficiency by changing the shift points, and you don't realize that the throttle is nearly wide open since the car isn't accelerating very hard at the low rpms. Of course the engineers who design eco mode probably know more about how to do this than I do. I know they mess with shift points, it wouldn't surprise me if they did other things too.
  - cmrdporcupine 8y ago
    EVs have no 'shift points' or changing gear ratios.
    - bluGill 8y ago
      Maybe or maybe not. Some EVs have a transmission - while it isn't strictly required (which is why others do not) for best acceleration you need one. If there is a transmission this is a shift point. Of course EVs have completely different operating parameters. The rest of my post was respect to a internal combustion engine.
      - cmrdporcupine 8y ago
        Some EVs have a transmission, yes. My Volt has a planetary gear set in order to share traction with the ICE. But that's not a pure EV. But what they don't generally have, unless they are conversions from ICE cars, is changing gear ratios. Torque is mostly constant across all RPMs in an EV, so there's not really a need for one.
- petre 8y ago
  You also kill the batteries in shorter amount time if you do not limit the acceleration. The habbit of pressing the accelaration to the bottom will drain lots of power from the battery. It also encourages reckless/sporty driving. Best way to do this is on passenger cars is to have an eco/sport switch. On a passenger bus or truck you don't need a sport switch, since those vehicles are meant to be driven responsibily.
- davidgould 8y ago
  Yes. Resistive losses in the motor and inverter are proportional to the current squared (I^2). Accelerating hard requires more current so 2x acceleration incurs 4x resistive loss. It's not a huge effect in most applications, but it does make a difference.

Obi_Juan_Kenobi 8y ago

Tesla introduced a "chill" driving mode for this very reason. It makes acceleration and braking (regen) much smoother and many owners speak highly of it.

Fnoord 8y ago
I was taught to drive like that in The Netherlands by my driving instructor. It is much safer (especially with deliberate bumps to slow you down in a neighbourhood where children play), saves you fuel, and it saves you your brakes. It does cost you a little bit time and this can add up if it means you miss a traffic light due to that but it could also mean that you still get a green light. So in the end, the loss is very little to nothing.

caf 8y ago

On gasoline (as opposed to diesel) engines, it actually used to mechanically open a butterfly valve that controlled the air intake (the throttle).