Noob Questions

[ChrisMiller]

I think the mathematics is quite general, maby, though in the case you describe running in B0 is what the cruise control would do in any event. But, yes, what I had specifically in mind was people speeding up and then lifting off the accelerator and running in B0 until they felt their speed had dropped too low and then speeding up again - that's clearly sub-optimal. And I'm not sure why you'd want to run in B0 for long distance cruising, since that throws away any regeneration energy available when you occasionally need to slow (more than 'occasional' on the roads I frequent!)

 

[maby]

It's also worth remembering that the paddles don't do anything that you can't achieve with the brake and accelerator pedals. The B level simply sets the amount of "virtual braking" that will be applied when you take your foot away from the pedals - whatever B setting you select, you can achieve the same effect as any other B setting by pressing one pedal or the other by an appropriate amount.

As far as I can see, the only exception to this is descending a hill with cruise control engaged - under these circumstances the B level determines the maximum amount of braking that will be applied to control the car's speed. I have a long and moderately steep hill that I have to descend as I approach my house. I normally am on cruise control when I do this and the speed limit is 40mph. If I have set the cruise control to 40 on the flat as I approach the hill and have the car in "D", it will run away on the way down and I run the risk of triggering the speed camera near the bottom - I need to set the braking to B5 before I enter the hill and then the descent will be perfectly controlled. I guess this is why engaging the cruise control disables B settings below B2 - it needs the braking level to be able to control the speed.

 

[ChrisMiller]

you can achieve the same effect as any other B setting by pressing one pedal or the other by an appropriate amount.

You can certainly achieve the same physical effect on the car using the brake pedal, but if you're in B0, you won't gain any charge in the battery. My local driving is along winding, hilly country lanes (many of them 'single track with passing places') and I find driving in B3 gives me what feels like a natural amount of deceleration when I lift off the accelerator (or, more likely for me, cancel the cruise control) approaching a bend. But if I'm turning onto another road, although B3 will eventual slow the car sufficiently, it's hard to judge exactly when to lift off to achieve the right speed at the turning. So I 'drop down' (up?) to B5 which means I can leave the cruise control in for longer.

 

[Claymore]

I think the mathematics is quite general, maby......... though in the case you describe running in B0 is what the cruise control would do in any event....

No it doesn't.

If you are using cruise control the default is B2

JimB

 

[maby]

you can achieve the same effect as any other B setting by pressing one pedal or the other by an appropriate amount.

You can certainly achieve the same physical effect on the car using the brake pedal, but if you're in B0, you won't gain any charge in the battery.....

That's not true - irrespective of the B setting, the first half inch or so of depression on the brake pedal engages regenerative braking - the mechanical brake only engages after that initial depression. You see this when you set off with a fully charged battery which will not permit full regeneration - a light touch on the brake pedal has no effect - a few miles later, once you have used up some of the charge, the same touch on the pedal will have a braking effect. The B setting simply determines how much regenerative braking is applied when you are not touching either pedal. If you select B5 and lift your foot off the accelerator while watching the left hand dial on the instrument cluster, you will see the regen level going well up. Lightly press the accelerator and the regen level will drop to zero - the same as you would get with the car in B0 and not touching either pedal. Put the car in B0 and lift your foot off the accelerator and the left hand dial will register no power flow in either direction, but if you gently depress the brake you will see the regen level rise.

 

[maby]

I think the mathematics is quite general, maby......... though in the case you describe running in B0 is what the cruise control would do in any event....

No it doesn't.

If you are using cruise control the default is B2

JimB

The default is B2 and you cannot select a lower level than this.

 

[Claymore]

I knew that.



JimB

 

[ChrisMiller]

The default is B2 and you cannot select a lower level than this.

I agree, but we're talking about a situation in which cruising at B0 (zero regeneration) downhill is just sufficient to maintain speed. In which case, that's precisely what cruise control will do. It will only engage regenerative braking when it needs to slow the car down.

the first half inch or so of depression on the brake pedal engages regenerative braking

In any state other than B0, regenerative braking starts as soon as the accelerator is released. It may be that it can be increased by gentle brake pressure, I haven't tried - I must give it a go