Eco,N or S and Kers 1,2 or 3 research

Is it true that in cruise control mode the kers does not work and no regeneration occurs?
 
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Robf said:
So... Does that mean the car (MG ZS) is regenerating whilst braking under cruise control?
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I'd have thought the car regenn'ed under any deceleration, whether it's "manual" or managed by ACC. If ACC brakes the car hard enough, the brake lights come on for sure.
 
smokie said:
I'd have thought the car regenn'ed under any deceleration, whether it's "manual" or managed by ACC. If ACC brakes the car hard enough, the brake lights come on for sure.
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While using ACC/Pilot the ZS not regen under braking/slowing it is all friction brakes, the 5 does regen.
They use different Bosch systems.
 
Gomev said:
The vehicle according to the manual........'is equipped with a cooperative regenerative
braking system (CRBS), this converts the kinetic energy of the vehicle into electric energy while braking and stores the energy in the HV battery, so as to prolong the driving range.'

That to me reads as it regens while actually braking and not while pressing the brake pedal a bit. I could be misunderstanding that, but If someone with actual knowledge can explain how that works, as opposed to guessing/assuming like me, then I am sure many would be interested.

My guess is as @Petriix has said The brake pedal will apply a combination of regenerative and friction braking but I am struggling with the concept of how as @Petriix and @BugEyed have also suggested that the first part of applying the brakes does not apply the brakes but just adds more regen.

@BugEyed with reference to you mentioning You can observe the regen level by looking at the amps on the power flow screen, of course you can. Observe whilst slowing under regen only and then apply the brakes, regen increases massively. This isn't because more regen is being added to regen in the first part of pedal travel, I believe this is part of the CRBS mentioned above and is a result of applying the friction brakes.
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I'm not sure why you think 'regenerative braking' requires use of friction between the pads and the disks - that's totally illogical. Applying the friction brakes can only waste energy as heat; the only way to recover energy is to use the motor as a generator, which is exactly what applying the brake pedal does. It's the same in hybrid cars. It's all computerised so that the balance between regenerative braking and friction through hydraulic force is optimised for maximum energy recovery in any given situation (with the obvious exception of the cruise control on the ZS).
 
The Prius used friction brakes only below 7mph as there was not enough regen power to slow the car down below that. At speeds above that it used regen first then friction if more, or quicker, braking was required.
 
Petriix said:
I'm not sure why you think 'regenerative braking' requires use of friction between the pads and the disks - that's totally illogical. Applying the friction brakes can only waste energy as heat; the only way to recover energy is to use the motor as a generator, which is exactly what applying the brake pedal does. It's the same in hybrid cars. It's all computerised so that the balance between regenerative braking and friction through hydraulic force is optimised for maximum energy recovery in any given situation (with the obvious exception of the cruise control on the ZS).
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I don't think 'regenerative braking' requires use of friction between the pads and the disks', you have totally misunderstood, and please point out where you think I have said that.
I am saying that when braking, i.e using friction between the pads and the disks, then increased regeneration happens as a consequence of braking/slowing down.

What I find illogical is that applying the footbrake does not apply the brakes, but applies regen only for a period before applying the friction brakes. If I think I need to apply the brakes I don't want the car saying 'oh hold on there........ I'll try a bit of regen first and see if that works!

Unless using two footed driving, the very nature of lifting off the throttle and moving the foot to the brake pedal will have started the regen process anyway. The addition of further friction based retardation will then increase the regen strength as can be witnessed on the power screen.
As regards to the computerisation being optimised for maximum energy recovery when braking, personally I would prefer the optimisation to be towards the braking and stopping the car.
I would welcome any evidence/documentation to support your theories.
 
Gomev said:
What I find illogical is that applying the footbrake does not apply the brakes, but applies regen only for a period before applying the friction brakes. If I think I need to apply the brakes I don't want the car saying 'oh hold on there........ I'll try a bit of regen first and see if that works!
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I don't think that's what happens.
Foot pressure operates the master cylinder and immediately applies brake pressure in all circumstances so that's a constant. What varies is the amount of assistance the car offers (directly through the servo and via regeneration). Both of these will be computer controlled.
 
I don't think the footbrake applies hydraulic pressure to the brake calipers initially, just to the ABS unit. I think there's a sensor, either on the pedal or on the ABS unit, that measures the amount and speed of pedal travel and applies regen initially then friction when heavier or quicker braking is required. Probably also linked to vehicle speed and rate of deceleration.
 
I continued to slide the corner was wide and no traffic so not a problem just caught out by kers 3, it was compacted snow and ice I think even just breaks might have given me a problem.
 
MarkLynn said:
I continued to slide the corner was wide and no traffic so not a problem just caught out by kers 3, it was compacted snow and ice I think even just breaks might have given me a problem.
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If you're on ice no amount of braking is going to help, if the wheels have locked up all you can do is take your foot off the pedal(s) and pray.
 
Kithmo said:
I don't think the footbrake applies hydraulic pressure to the brake calipers initially, just to the ABS unit. I think there's a sensor, either on the pedal or on the ABS unit, that measures the amount and speed of pedal travel and applies regen initially then friction when heavier or quicker braking is required. Probably also linked to vehicle speed and rate of deceleration.
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It would be a really bad design if that were so :unsure:
 
Gomev said:
Is it true that in cruise control mode the kers does not work and no regeneration occurs?
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No that is not true. If you are using cruise control and going down a 10% hill at about 60mph cruise then observe the power meter goes into the blue area and if you watch the battery amps they go negative whilst the electric motor is being used in reverse to stop the car speeding up due to gravity.
That is kers working.

But it seems to me it is never a good idea to use cruise if the road is more than about 5% up or down. Less than 5% hill and you can use nudge uphill to drop the speed and keep the power less than 20%
 
rogerco said:
If you are using cruise control and going down a 10% hill at about 60mph cruise
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I don't think that really qualifies as using cruise control in this context, although it proves that the cruise control being turned on doesn't automatically stop regen.
 
Gomev said:
Is it true that in cruise control mode the kers does not work and no regeneration occurs?
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rogerco said:
No that is not true. If you are using cruise control and going down a 10% hill at about 60mph cruise then observe the power meter goes into the blue area and if you watch the battery amps they go negative whilst the electric motor is being used in reverse to stop the car speeding up due to gravity.
That is kers working.

But it seems to me it is never a good idea to use cruise if the road is more than about 5% up or down. Less than 5% hill and you can use nudge uphill to drop the speed and keep the power less than 20%
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Sorry, that was a poor post , it was a google translation of the post by someone else (can't remember name) re their ZS EV, that I accidentally pasted there! A moderator has edited it, so can't remember the original post.
As I stated before, The ZS does not use regen with ACC, the 5 does.
 
Wazzajnr said:
Why would it be a "really bad design"?
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It makes the software element safety critical and that vastly increases cost and complexity. I've worked for a long time in safety critical system design and the general rule is to avoid software dependence if it is physically possible to do so.
Good (safe) design would be to make the core functionality of braking software independent.
 
Alb said:
It makes the software element safety critical and that vastly increases cost and complexity. I've worked for a long time in safety critical system design and the general rule is to avoid software dependence if it is physically possible to do so.
Good (safe) design would be to make the core functionality of braking software independent.
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I would imagine the ABS unit would have a failsafe where it normally uses hydraulic valves that are electronically controlled in normal use and default to hydraulic only when there is no electronic signal. Thus making the core functionality of braking totally hydraulic in a case of failure.
 
Alb said:
Foot pressure operates the master cylinder and immediately applies brake pressure in all circumstances so that's a constant. What varies is the amount of assistance the car offers (directly through the servo and via regeneration). Both of these will be computer controlled.
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That's precisely what happens. The ABS unit is between the electronic servo and the brake calipers and only reduces the hydraulic pressure per channel when a wheel locks, so in the event of a failure does nothing.
In the event of a servo failure the pedal is just much heavier but still stops the car if enough force is applied and moves no further than usual.
 
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