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

[CuriousIslander]

I am not sure that this is the best forum for this thread, but here goes. If anyone can suggest a better location then please let me know.
I am interested in the relative merits of driving in different modes and Kers settings (MG5 SR) in relation to battery efficiency. Has any detailed research been done to show, for instance, whether Kers 1 on motorways/fast dual carriageways, coupled with driving mode N is the most efficient in terms of battery use, not forgetting different driving speeds - I am assuming here that speeds are in the mid 60's as this seems to be a reasonable trade-off between speed and efficiency? There is also the use of Cruise Control to consider as well. There are clearly a number of variables to be tested, and the whole area would need some careful testing strategy. I have tried a few variations but can come to no conclusions. Do others have any feelings one way or the other? There are many of you who do far greater mileages than me, who will therefore have much greater experience.
Just still curious
PS Maybe this is something "James and Kate" could throw light on as James does substantial miles in his MG5

 

[Alb]

I don't fixate on the issue of energy consumption but it is useful to emphasise the point that energy use will be dominated by your driving style regardless of how you set Mode and KERS.

 

[pjmuk]

In my view KERs settings don't make any difference to energy saving in an MG5, it's just a matter of personal preference.
If the car slows down it charges the battery. On KERs 1 you may have to dab the brakes, but they don't use the actual pads unless you stand on them or come to a stop anyway, they just charge the battery too.
My preference is ECO for drive mode - less wheel spin but all the power is there if you need it, and KERs 2 - i.e. the default

 

[Robf]

So should you be using eco mode for slippery conditions e.g. snow, black ice etc? just wondering.

 

[pjmuk]

So should you be using eco mode for slippery conditions e.g. snow, black ice etc? just wondering.

Yes, a bit like pulling off in 2nd gear in slippery conditions

 

[Jomarkh]

So should you be using eco mode for slippery conditions e.g. snow, black ice etc? just wondering.

I would not use Kers 3 in poor conditions but I don't think it matters if in eco or normal

 

[BugEyed]

I am interested in the relative merits of driving in different modes and Kers settings (MG5 SR) in relation to battery efficiency

I suspect that there are too many variables for an owner to get any accurate data, and even the factory would struggle.

FWIW:

• The slower you drive the less power will be consumed both due to aerodynamic drag and rolling resistance. But it is sometimes nice to avoid holding up traffic, particularly lorries.
• The motor is marginally more efficient at close to full torque and 50% revs. But note the comment above on speed and power consumption.
• Warm weather and batteries are more efficient, hence the battery heater option. Obviously you need to balance energy consumption in heating to gain more efficiency, but it is certainly worthwhile at extremely cold temperatures if less of an issue in the UK Summer.
• Cruise control - constant speed up and down hill is less efficient than allowing the car to speed up downhill on zero power rather than using KERS to stop it speeding up because of the losses in KERS. Clearly there are issues regarding speed limits and the cars in front, but in theory you should try to avoid using KERS as the roundtrip efficiency is under 80%
• The sensitivity of KERS is personal choice. If you find it hard to avoid using it accidentally at higher levels then settle for lower levels, but if that means you use the friction brakes then that's less good. As above try to avoid any braking!

In my opinion, life's to short to obsess about it - just enjoy the car.

 

[Petriix]

Life's definitely too short to put two 'o's in 'too'... Otherwise a great post. It's worth having an awareness of this information, then you can make an informed decision as you drive.

I would add that it's even more nuanced than that because it's unknown exactly how the friction brakes are blended with KERS when the brake pedal is depressed. I believe it's different in 'sport' mode where more friction seems to be applied earlier in the pedal travel, otherwise I think the first part of the pedal only uses KERS (unless you're 100% charged).

I'm erring towards using KERS 3 more frequently as I'm finding it easier to avoid accidentally slowing too much with experience. In practice I tend to put it in KERS 3 the first time I want to be slowing faster than the default in KERS 2, then I just leave it in 3.

I never use 'Eco' mode. It just sucks the life out of the car.

 

[Ian MG5]

Hi
I have got problems with my friction brakes when I first thing in the morning the squeak like old rubber brake blocks on a bicycle wheel then after I get off the driveway it’s gone
So further up this post someone said you have to stand on the friction brakes for them to work
Does this mean I have a problem some where else in the drive train
It’s been back to the dealership twice now and still not cured the problem
I’ve even sent multiple videos with the noise
???????

 

[Richal666]

I would not use Kers 3 in poor conditions but I don't think it matters if in eco or normal

Sport mode in dry normal conditions is not recommended either, I had wheel spin accelerating from 40mph, awful tyres don't help. I tend to stay normal mode and kers 2 mostly as simply it defaults to that always.

 

[5teep]

When I first got the car I drove everywhere in Eco and kers3 but since worked out that kers 3 is really too aggressive on the open road. It cuts your speed down so much you have to accelerate to get it back, using up any power gained.
Now I normally choose eco and kers 2 as a compromise and I think I'm more efficient with it but playing with normal mode too, there's not a lot of difference that I can make out.

 

[Jomarkh]

In kers 3 just don't take your foot off the accelerator too fast, I love one foot driving.

 

[MarkLynn]

I would not use Kers 3 in poor conditions but I don't think it matters if in eco or normal

So this past winter when the road was very icey kers 3 locked my drive wheels at 15mph the skid lasted for about 15' more than long enough for me to learn kers3 is not for icey conditions

 

[Gomev]

Life's definitely too short to put two 'o's in 'too'... Otherwise a great post. It's worth having an awareness of this information, then you can make an informed decision as you drive.

I would add that it's even more nuanced than that because it's unknown exactly how the friction brakes are blended with KERS when the brake pedal is depressed. I believe it's different in 'sport' mode where more friction seems to be applied earlier in the pedal travel, otherwise I think the first part of the pedal only uses KERS (unless you're 100% charged).

I'm erring towards using KERS 3 more frequently as I'm finding it easier to avoid accidentally slowing too much with experience. In practice I tend to put it in KERS 3 the first time I want to be slowing faster than the default in KERS 2, then I just leave it in 3.

I never use 'Eco' mode. It just sucks the life out of the car.

If the first part of the pedal only uses KERS then there would be no point in using the brake, you would just lift off. If you need to brake you need to brake, I would be scared if I put my foot on the brake and it just slowed like in KERS.
KERS is active when braking, and I'm hazarding a guess here, simply because the car is slowing and therefore reproducing a more aggressive form of lifting off the throttle.

 

[BugEyed]

If the first part of the pedal only uses KERS then there would be no point in using the brake

That's exactly what it does in some circumstances, such as if you are driving in KERS1 and apply the brakes gently then the first part of the pedal movement applies only KERS (presumably what would come under KERS2 and 3) before then adding friction braking. Rest assured that if you apply the pedal significantly you get to the friction braking straight away.

So this past winter when the road was very icey kers 3 locked my drive wheels at 15mph the skid lasted for about 15' more than long enough for me to learn kers3 is not for icey conditions

The same would have happened if you had been in a manual ICE in a low gear at mid to high revs and used a similar amount of engine braking. But of course you wouldn't drive like that - in those conditions you'd avoid the low gear/high revs scenario.
I find the length of time that KERS appears to take to disengage slightly worrying and whilst I haven't experienced it in the MG I had a similar experience in my previous LEAF at the higher level of Regen.

 

[Petriix]

If the first part of the pedal only uses KERS then there would be no point in using the brake, you would just lift off. If you need to brake you need to brake, I would be scared if I put my foot on the brake and it just slowed like in KERS.
KERS is active when braking, and I'm hazarding a guess here, simply because the car is slowing and therefore reproducing a more aggressive form of lifting off the throttle.

You're making the incorrect assumption that KERS 3 applies the maximum amount of regenerative braking; it doesn't, by quite some margin. The brake pedal will apply a combination of regenerative and friction braking depending on the driving mode, state of charge and how hard you press.

The initial part of the pedal travel uses no hydraulic brake pressure at all unless you're in 'N' or at close to 100% state of charge. You can observe the regen level by looking at the amps on the power flow screen.

 

[Gomev]

I would add that it's even more nuanced than that because it's unknown exactly how the friction brakes are blended with KERS when the brake pedal is depressed. I believe it's different in 'sport' mode where more friction seems to be applied earlier in the pedal travel, otherwise I think the first part of the pedal only uses KERS (unless you're 100% charged).

...

That's exactly what it does in some circumstances, such as if you are driving in KERS1 and apply the brakes gently then the first part of the pedal movement applies only KERS (presumably what would come under KERS2 and 3) before then adding friction braking. Rest assured that if you apply the pedal significantly you get to the friction braking straight away.

...

You're making the incorrect assumption that KERS 3 applies the maximum amount of regenerative braking; it doesn't, by quite some margin. The brake pedal will apply a combination of regenerative and friction braking depending on the driving mode, state of charge and how hard you press.

The initial part of the pedal travel uses no hydraulic brake pressure at all unless you're in 'N' or at close to 100% state of charge. You can observe the regen level by looking at the amps on the power flow screen.

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.

 

[BugEyed]

I agree with @Petriix - the servo in the MG5 (and most EVs) is a special one that is controlled electronically. Initial pressure applied by the driver is interpreted and in the event that sufficient braking can be provided by the Regen alone no significant friction braking is applied. Only in the event of more braking being requested than is available from Regen alone is significant electronic servo pressure applied to the hydraulic system and hence the friction brakes come into significant use. The CRBS is the name given to the clever balancing of the two systems.

Edit - the normal limit on the Regen applied when braking using the brake pedal is the maximum charging rate for the battery - the energy has nowhere else to go. This means that on cold days or when the battery is fully charged less regen is allowed and hence the friction brakes are used at lower brake pedal pressures.

 

[Robf]

So... Does that mean the car (MG ZS) is regenerating whilst braking under cruise control?

 

[Gomev]

So... Does that mean the car (MG ZS) is regenerating whilst braking under cruise control?

No.