Auto sense regeneration level ground effect.

[Jetfuel]

BMW, there seems to be no down hill auto sense with regards to the weight of the i3 and he down hill angle of the car (effect of gravity). the car is not able to come to a stop with in more than a 30 degree slope. Why not have a changeable level ground effect with regards to regeneration?

 

[MikeS]

I guess because it would be too complex for such a limited use.

 

[noakey]

BMW, there seems to be no down hill auto sense with regards to the weight of the i3 and he down hill angle of the car (effect of gravity). the car is not able to come to a stop with in more than a 30 degree slope. Why not have a changeable level ground effect with regards to regeneration?

Use the other pedal.

 

[MikeS]

:lol:

 

[BrianStanier]

Regeneration can only occur when the car is moving. If the car is on level ground the car will be almost at a standstill when regeneration stops and the car can remain (almost) stationary. But on a slope the car will continue to move. The only way it can stay still is to drive the electric motor to provide thrust to counter gravity which uses power and is wasteful. So use the brake.

 

[jadnashuanh]

If I'm in a long line at a traffic light on a hill, I"ll try to stop early (regen only, otherwise it doesn't make much sense), and then let it roll slowly. If you are lucky and time things properly, you're still moving and close to the car ahead when the light turns green again.

 

[i3Alan]

Regeneration can only occur when the car is moving. If the car is on level ground the car will be almost at a standstill when regeneration stops and the car can remain (almost) stationary. But on a slope the car will continue to move. The only way it can stay still is to drive the electric motor to provide thrust to counter gravity which uses power and is wasteful. So use the brake.

Can't say for sure what the i3 does, but if the motor windings are completely shorted, it is nearly impossible to turn much beyond zero RPM. If the i3 could hold the windings to zero volts, I doubt the i3 would creep more than a few inches per minute, even on a fairly steep slope. Although still waiting on my i3 to arrive (this week, maybe!), from my test drives, it seems that the control electronics do clamp down pretty hard to continue deceleration well beyond getting useful regeneration.

 

[Chrisn]

Given the existing electronics and sensors for ACC and Hill Assist, it would be possible to have the car come to complete stop and hold position on even a steep hill without ever having to touch the brake. Behind the scenes, the car would be engaging the mechanical friction brakes to hold the car still.

But that's not how a "normal" car works, so not sure why BMW would think to add such a feature.

 

[Jetfuel]

Well three things are present in all good ideas, confusion, ridicule and question... so let me explain in more detail.

1/3 of the cars moving state is spent either flat, up hill or down hill. (1/4 over all state of the car if you count just being turned off). BMW has a solution for uphill, the auto park break ACC to hold on a hill, and regenerative single pedal drive when not expending electrons (flat).

If the car can sense what angle relative to gravity, why not have a way that the car would apply the regenerative power system while traveling in a downward angle for more effect? meaning adjustable for the driver (even even down to relative slow speeds)? Would be possible even at a slow rate of decent down hill (5-15 kph) to turn a charing wheel given the weight of the car, gravity and Mr. Newton. Needless to say I live where there are lots of hills. again 1/3 of a cars moving state is down hill.

as for ridicule, Mr. Edison, please see this young guy Nicole Tesla's idea. If this reference is lost on you, suggest you use the WWW to find out more.

Questions?

we of course will always have a break pedal in the car, but why use it if you can do it another way...

 

[jadnashuanh]

I find that I rarely need to back off on the pedal all the way to stop where I want to until I'm actually stopped or barely moving...it just takes a little practice. IOW, YOU control the amount of regen the car produces, up to the design max from using a lot, none (coasting), to using the maximum. If cruising, the cruise control does the same thing to maintain the speed going downhill - if the hill is steeper, it will use more regen to hold the speed steady. Making it more complex doesn't seem to be a worthwhile endeavor - IMHO, you have all of the control on the level of regen you need under all circumstances. I think that I read, you can get even more regen if you switch out of comfort mode, but the control is the same. Part way, and you're coasting, press further, you're either cruising, and press more and you're accelerating. Really, letting off completely on the go pedal feels like a pretty good stab at the brakes, but it is entirely regen. For this reason, the logic also turns on the brake light automatically so you have less chance of being rear-ended. My impression is that after the software update in July, they decreased the level of regen slightly, but I have no way to measure it...this is seat of the pants, subjective impression.