Cruise control does use regen!

[SCB86]

I know there have been discussions on the cruise control not using regen on the ZS, but today I found out regen is used!

I was going down a hill with the ACC set to 20MPH and the car started to gain momentum over the set speed. Changing the KERS mode increased or decreased the braking action of the car depending on if it's set to 1, 2 or 3.

Then I tried the ACC on a flat road; coming up behind slowing traffic for a traffic light I adjusted the KERS mode up and down, each mode increased or decreased the braking force.

It actually made the braking action of the ACC less aggressive when slowing down in KERS mode 1 compared to 3.

 

[JodyS21]

V interesting. It's not something I've tried out yet myself.
I assume you actually saw the Amps go negative?

 

[SCB86]

I didn't check the amp readout, but it's definitely regen being used - it's exactly the same sensation as when you're coasting without ACC on and change the KERS mode.

 

[Tim Green]

I cannot imagine how one could design a cruise control that does not use Kers!
You need some way of slowing the car and braking would be a last resort.

 

[Phil Hayward]

My car does not use regen in ACC, power metre reads zero going down a hill with ACC set.
Brakes are hot at the bottom of the hill, disc rust cleaned, do it once week.
It should use regen in ACC. ACC is too aggressive on undulating roads

 

[SCB86]

If it doesn't use regen, I don't understand why changing the KERS setting adjusts the retardation when slowing down with ACC activated

 

[stryker]

I didn't check the amp readout, but it's definitely regen being used - it's exactly the same sensation as when you're coasting without ACC on and change the KERS mode.

Please do. If there is charging happening - have you recently had a firmware update?

We're considering the ZS as our 2nd EV, and know how much regen benefits the range on our 3 on autopilot - it's more efficient than a human driving for sure.

 

[SCB86]

It has the newest software fitted. I'll check the amp reading tomorrow and report back

 

[SCB86]

I can confirm that the amp readout goes to -1
The car definitely changes how much it's slowing down with ACC when you toggle through the KERS options, so I'm a little perplexed as the amps doesn't recover what it normally does under regen.

Can someone else try it on their car to see if it's an actual feature? If you put the car in KERS 1 and then use ACC, when slowing down for other traffic toggle through the KERS 2-3 and you should feel a marked difference in retardation.

 

[Cocijo]

I’ll give it a try later. I’ve looked at the amps when descending a very steep hill using ACC set to 30mph and regen 3 and there does not appear to be any regen (-ve) current happening. I’ve not tried changing regen setting during ACC when it’s decelerating but will give it a try.

 

[Cocijo]

I’ve just had a play on my way home and these are my results.
I drove down a steep hill at 50mph and then set the ACC to 40mph. This was while in regen 1 in normal mode.
I then flicked through from regen 1 to 2 to 3 to see what effect it had while under ACC and still slowing to reach the set speed.
Each time I increased the regen setting I heard the friction brake pump briefly activate. Increasing the regen level appeared to increase braking effect until the set speed was reached.
I didn’t see any regen evidence on either the main power gauge or the electrical information screen.
It looks like the regen button is connected to the friction brakes when using ACC, although I don’t know exactly why.
Under a lighter regen (say regen1) the ACC also seems much smoother generally during braking. Whilst I could be wrong I can see no evidence that regen is used under ACC.

 

[SCB86]

It's a puzzler, as you said why would the KERS button affect the mechanical braking system
But at least I know my car isn't faulty Retardation is definitely smoother in level 1, shame you can't default to it on start up.
Changing the mode and the regen level every single time you get in the car is irritating.

 

[Electrifried]

I know there have been discussions on the cruise control not using regen on the ZS, but today I found out regen is used!

I was going down a hill with the ACC set to 20MPH and the car started to gain momentum over the set speed. Changing the KERS mode increased or decreased the braking action of the car depending on if it's set to 1, 2 or 3.

Then I tried the ACC on a flat road; coming up behind slowing traffic for a traffic light I adjusted the KERS mode up and down, each mode increased or decreased the braking force.

It actually made the braking action of the ACC less aggressive when slowing down in KERS mode 1 compared to 3.

 

[Electrifried]

Adjusting the kers mode will naturally adjust the amount of regeneration on the vehicle wether it is in cruise control or not. What the ACC will not do is adjust the amount of regen in a set situation to control speed going down a hill, it will go to the friction brakes to control the speed. This can easily be seen by simply switching off the acc and you will see the difference by using the regen manually on your Accelerator pedal.( I may be wrong but I do not think the cruise control can be set below 30mph)

 

[Cocijo]

Cruise control can be set at 20mph on my ZS. There is no regen under ACC that I have ever experienced. It uses 100% the friction brakes to control set speed.

 

[JodyS21]

It's all very confusing this.
Is the main point we're making, that it will not purely try to use regen under ACC to slow down a little bit? Is always engages the physical brakes - which also may trigger some regen to happen too but as a secondary effect?

 

[Cocijo]

Yes, we have sort of lost our way a little. From my perspective I can say the following;

when operating under ACC there is no regen at all used to control the vehicle speed

friction brakes alone are used to keep a constant speed as required

the interesting fact is that when under ACC and slowing to reach a set speed if the regen setting is changed it affects the severity of friction braking and you can hear the brake pump operating - still without any regen.

the regen setting at a lower level generally makes driving under ACC smoother - again there is no regen just friction braking.

not sure what this means but interesting that the regen button affects the friction braking severity under ACC.

 

[JodyS21]

Yes, we have sort of lost our way a little. From my perspective I can say the following;

when operating under ACC there is no regen at all used to control the vehicle speed

friction brakes alone are used to keep a constant speed as required

the interesting fact is that when under ACC and slowing to reach a set speed if the regen setting is changed it affects the severity of friction braking and you can hear the brake pump operating - still without any regen.

the regen setting at a lower level generally makes driving under ACC smoother - again there is no regen just friction braking.

not sure what this means but interesting that the regen button affects the friction braking severity under ACC.

When we (manually) lift off the accelerator pedal, the kers mode, obviously makes the big difference on how quickly the car decelerates....
Now could it be that effectively the ACC has told the "car" to lift off the accelerator (stop power), that then because of the way the system works "looks at" the kers mode to determine how quickly to decelerate, at the same time because it's under ACC control maybe it's been told to use friction brakes and not rely on/use regen. Therefore the rate of deceleration is loosely related to the kers mode????

Another way of looking at it; from the ACC brains point of view, if it needs to decelerate - it "lifts off" the accelerator and "presses" the brake pedal. Maybe it does not have a state of neither pedal engaged (when is when regen mainly occurs)....????

 

[SCB86]

I still don't understand why changing the regen mode affects the mechanical braking if it doesn't use the KERS.

I might contact MG for clarification.

 

[Electrifried]

When we (manually) lift off the accelerator pedal, the kers mode, obviously makes the big difference on how quickly the car decelerates....
Now could it be that effectively the ACC has told the "car" to lift off the accelerator (stop power), that then because of the way the system works "looks at" the kers mode to determine how quickly to decelerate, at the same time because it's under ACC control maybe it's been told to use friction brakes and not rely on/use regen. Therefore the rate of deceleration is loosely related to the kers mode????

Another way of looking at it; from the ACC brains point of view, if it needs to decelerate - it "lifts off" the accelerator and "presses" the brake pedal. Maybe it does not have a state of neither pedal engaged (when is when regen mainly occurs)....????

The thing is Jody is that the ACC has been taken directly from the ICE version of the ZS and has no software or programming to engage the regen on the EV therefore it works exactly the same as the ICE version of the car. We know that sounds crazy but that is what SAIC have done