Regenerative Braking

[greendwarf]

I really don't think it's wise using B5 braking on the motorway - it doesn't light the brake lights and there are plenty of shunts with normal braking anyway.

"

When I want to slow down and there is not much traffic behind me there is no issue. I have done over 10,000 mile using this method.

I get your point though

That was part of the point of my original post, is that I can set it to coast (B0) on the motorway and if I want to apply regen I touch the brake pedal. Depending upon how far I press depends on the level of regen and how quickly I do or don't stop, and my brake lights are on.

In general though I just treat it like a normal car, leave it in Drive and let it do its own thing.

I've found B0 equally useful in Sarf London to coast down long inclines where Drive would have reduced the speed too quickly. But, I did notice today on a steeper hill that working up through to B5 left very little subtleness in the bank pedal when I did need to press it - almost an emergency stop

 

[anko]

But, I did notice today on a steeper hill that working up through to B5 left very little subtleness in the bank pedal when I did need to press it - almost an emergency stop

When your setting is B5 and you hit the break panel, automatically you are doing more than B5, initially electrical, eventually mechanical. So, the effect of hitting the break panel when in B5 doesn't say a lot about the B5 setting itself.

B5 is programmed to reduce speed with 0.11 G or 1.0 m/s2, regardless of incline, decline, wind conditions, current speed, weight, etc., Of course on a steep incline speed may be reduced faster and on a steep decline speed may be reduced less quickly. But the target value is far less than what would feel like an emergency break. Are you sure you did not push the pedal so hard that you applied the mechanical brakes?

 

[greendwarf]

But, I did notice today on a steeper hill that working up through to B5 left very little subtleness in the bank pedal when I did need to press it - almost an emergency stop

When your setting is B5 and you hit the break panel, automatically you are doing more than B5, initially electrical, eventually mechanical. So, the effect of hitting the break panel when in B5 doesn't say a lot about the B5 setting itself.

B5 is programmed to reduce speed with 0.11 G or 1.0 m/s2, regardless of incline, decline, wind conditions, current speed, weight, etc., Of course on a steep incline speed may be reduced faster and on a steep decline speed may be reduced less quickly. But the target value is far less than what would feel like an emergency break. Are you sure you did not push the pedal so hard that you applied the mechanical brakes?

By the time I braked speed was less than say 10mph but I was surprised by the lack of progression in the pedal compared to lower B values. So - yes I hit the mechanical brake too hard. Nothing wrong with the car merely my lack of experience at using such a high B setting, so a useful lesson before I go skiing in the Alps where I expect to need to use Regen more on downhill slopes :lol:

 

[highlevel]

B5 is programmed to reduce speed with 0.11 G or 1.0 m/s2, regardless of incline, decline, wind conditions, current speed, weight, etc., Of course on a steep incline speed may be reduced faster and on a steep decline speed may be reduced less quickly. But the target value is far less than what would feel like an emergency break. Are you sure you did not push the pedal so hard that you applied the mechanical brakes?

If the battery is fully charged will B5 still operate at 0.11G or 1.0M/s2?

How would the garage measure this. ?

 

[maby]

B5 is programmed to reduce speed with 0.11 G or 1.0 m/s2, regardless of incline, decline, wind conditions, current speed, weight, etc., Of course on a steep incline speed may be reduced faster and on a steep decline speed may be reduced less quickly. But the target value is far less than what would feel like an emergency break. Are you sure you did not push the pedal so hard that you applied the mechanical brakes?

If the battery is fully charged will B5 still operate at 0.11G or 1.0M/s2?

How would the garage measure this. ?

No, it will not - regen braking has little effect with a fully charged battery - the car needs somewhere to dump the current coming off the generator. Some lorries have "electric braking" which is effectively the same thing - but since they do not have the rest of the hybrid systems including the battery pack, they have high power resistance elements which are air cooled to soak up the power from the generator coupled to the wheels. If you intend to make heavy use of regen braking, then you need to make sure that you run the battery down a bit first.

 

[Andy123]

Silly question - does using the footbrake charge the generator or does that energy just get used up in heat in the discs/pads (or noise, if you're in The Sweeney)?

 

[maby]

Silly question - does using the footbrake charge the generator or does that energy just get used up in heat in the discs/pads (or noise, if you're in The Sweeney)?

depends on how hard you press it. Gentle depression of the footbrake turns on regenerative braking - pretty much the same effect as pulling the paddles, but it does also illuminate the brake lights. Deeper depression of the brake pedal will engage the friction brakes and you start to burn off energy as heat. There has been some discussion as to whether or not the disks are also engaged lightly during that initial pressure on the pedal - I'm not sure either way. There does not appear to be anything you can do with the paddles that you can't do with the pedal as far as regen braking is concerned, but the paddles will never engage the disks.

 

[Andy123]

Cheers, useful - when I'm trying to drive as sensibly as possible (in a 3.0L land rover...) I tend to try to brake as lightly as I can, so assuming I get a Phev I'll probably give that a bash. Is there a definite difference in "feel" from when it's regenerating or using the discs?

 

[anko]

Silly question - does using the footbrake charge the generator or does that energy just get used up in heat in the discs/pads (or noise, if you're in The Sweeney)?

depends on how hard you press it. Gentle depression of the footbrake turns on regenerative braking - pretty much the same effect as pulling the paddles, but it does also illuminate the brake lights. Deeper depression of the brake pedal will engage the friction brakes and you start to burn off energy as heat. There has been some discussion as to whether or not the disks are also engaged lightly during that initial pressure on the pedal - I'm not sure either way. There does not appear to be anything you can do with the paddles that you can't do with the pedal as far as regen braking is concerned, but the paddles will never engage the disks.

Indeed, when you press the footbrake harder it will use the mechanical break and convert some of the energy into heat. But it will still regen. So no, not all energy is converted into heat.

 

[anko]

B5 is programmed to reduce speed with 0.11 G or 1.0 m/s2, regardless of incline, decline, wind conditions, current speed, weight, etc., Of course on a steep incline speed may be reduced faster and on a steep decline speed may be reduced less quickly. But the target value is far less than what would feel like an emergency break. Are you sure you did not push the pedal so hard that you applied the mechanical brakes?

If the battery is fully charged will B5 still operate at 0.11G or 1.0M/s2?

How would the garage measure this. ?

This is how they do it

This shows regen breaking from 143 km/h (approx 90 mph, point A in the graph) to 22 km/h (approx 14 mph, point B in the graph). What you can see is that just before reaching point B (where they hit the accelerator again), deceleration goes down towards 0 m/s2. Regen breaking will not bring you to a complete stop. As a matter of fact, if you are completely stopped and release the brake, the car will actually start rolling, even in B5. This is to mimic the "crawling" feel automatic gearboxes give us.

 

[gwatpe]

This data was supplied from a dealer scan tool? It would be great to get the codes for say a typical OBD2 tool.

 

[Ozukus]

B5 is programmed to reduce speed with 0.11 G or 1.0 m/s2, regardless of incline, decline, wind conditions, current speed, weight, etc., Of course on a steep incline speed may be reduced faster and on a steep decline speed may be reduced less quickly. But the target value is far less than what would feel like an emergency break. Are you sure you did not push the pedal so hard that you applied the mechanical brakes?

If the battery is fully charged will B5 still operate at 0.11G or 1.0M/s2?

How would the garage measure this. ?

This is how they do it

This shows regen breaking from 143 km/h (approx 90 mph, point A in the graph) to 22 km/h (approx 14 mph, point B in the graph). What you can see is that just before reaching point B (where they hit the accelerator again), deceleration goes down towards 0 m/s2. Regen breaking will not bring you to a complete stop. As a matter of fact, if you are completely stopped and release the brake, the car will actually start rolling, even in B5. This is to mimic the "crawling" feel automatic gearboxes give us.

What I find interesting in this post isn't as much the braking but the increase in SOC.

 

[anko]

This data was supplied from a dealer scan tool? It would be great to get the codes for say a typical OBD2 tool.

Actually, I got it from the local distributor. Don't know what they used. Don't know the codes