Regenerative Braking vs. Coasting

[toystwo]

I don't understand why the i3 doesn't allow coasting vs. immediately going to regenerative braking when lifting off the accelerator pedal. This must decrease range as converting the energy back to storage in the battery is not as efficient as using the energy in coasting. I understand the Volt has a choice of modes - why doesn't the i3?

 

[m11wlk]

Hi

I read one of the recent first drive reviews which commented on the lack of a coasting function but remembered reading about one specifically being a feature. I think it is something I would appreciate.

The press pack states, "And the “coasting” facility further enhances the user-friendly nature of single-pedal control. The BMW i3’s accelerator has a distinct “neutral” position; i.e. rather than switching straight to energy recuperation when the driver eases off the accelerator, the electric motor uses zero torque control to decouple from the drivetrain and deploy only the available kinetic energy for propulsion. In this mode, the BMW i3 glides along using virtually no energy at all." (p7 https://www.press.bmwgroup.com/pressclub/p/pcgl/download.html?textId=178666&textAttachmentId=222601 )

I wonder if the feature is not as 'distinct' as BMW claim so some drivers don't notice it, or it hasn't been activated?

Michael

 

[toystwo]

That is great - thanks for pointing it out. The pedal method may even be superior to a button if the whole one pedal driving concept is as engaging as BMW implies.

In the same place in the document (page 20), BMW states that the i3's recuperation increases range up to 20% compared to "traditional" methods. I don't understand how what BMW is doing is more efficient. Is just that the regeneration is so aggressive that one is presumably using the friction brakes less?

 

[AndrewDebbie]

I haven't driven an i3 yet but I have driven a BMW ActiveE.

BMW's regen is far more aggressive than what Nisan use on Leaf.

 

[ChrisC]

There is a coasting deadband in the middle of the accelerator pedal's travel.

 

[toystwo]

This comment from the CarConnection review does not bode well. I don't want to be looking down (vs. at traffic) to determine if I'm coasting or not. Odd that they make the most efficient way to drive difficult to achieve.

"And BMW has retained a gliding or coasting mode, between acceleration and regen, although the software control is now so seamless that you have to watch the power display through the steering wheel to find it."

Comment is in the Performance section:


http://www.thecarconnection.com/review/1087788_2014-bmw-i3_performance_3