MG ZS EV regenerative braking is limited please use brake

[Mysteronz]

Has anybody else had this issue?

Using the new comfort software update if that is of help, cant find any record of this error within the user manual or any google search!

any help appreciated!

 

[Mgkev]

It’s because you HV battery is fully charged and so regen has nowhere to go so it is reduced until some charge is used up.

 

[Mysteronz]

Thanks Mgkev you are right on that - makes perfect sense.

what however does seem odd is that despite being on eco mode and kers 3 even when the battery is c50% depleted the kers reduction in speed seems much less than before. Has anyone noticed this,possibly after the software update?

 

[simon]

When does the regen start working? 99% or lower?

 

[Kithmo]

I fully charged mine last night and drove about a mile before I needed to slow down and it worked ok then.
I've got so used to the KERS3 on the MG now that when I drove my Prius today I felt like it was running away from me when I took my foot off the accelerator.

 

[Mysteronz]

When does the regen start working? 99% or lower?

Didnt seem to matter what % it was on, very odd might be worth checking on setting 2/1 to see if that makes a difference.

 

[Mysteronz]

The ACC was accidently on over a week a go but turned off before todays journey if that is any cause

 

[simon]

I fully charged mine last night and drove about a mile before I needed to slow down and it worked ok then.
I've got so used to the KERS3 on the MG now that when I drove my Prius today I felt like it was running away from me when I took my foot off the accelerator.

Thank you for that. I'm looking forward to getting used to the regen

 

[simon]

The ACC was accidently on over a week a go but turned off before todays journey if that is any cause

It is a shame the regen isn't used on ACC.

 

[Mgkev]

Maybe it’s so that the brakes are warm enough if the car tries to do an emergency stop at high speed.
Or, maybe, it allows the brakes to get exercised to stop them seizing up which EVs are notorious for. Watch Byorn Nylands’ latest YouTube video.

 

[KasEV]

@Mysteronz
I have not noticed any issues with Regen pre or post comfort 2 upgrade.
Also please do not get confused about this Regen does not work when you battery is 100% full issue and in ACC mode issue.
In both case the car will slow down as soon as you foot comes of the accelerator.
The issue then is when does the brake lights come on to indicate you are slowing down.
This is when things become complex and a lot depends on how the vehicle is set up in regards to dual regenerative and hydraulic braking etc. There is now an international worldwide standard by which regen braking should be setup so it is uniform in all cars. The American have their own standard but it is in principle same as the international one. I can not say for sure for ZS EV but it is thought that this issue so far as the ACC in ZS EV is that the car slows down when ACC is triggered by hydraulic braking, the brake lights come on but regen does not kick in . I have not tested this myself but apparently it is amendable to an update and MG may update their software by end of this year to sort this out. Again this is just a rumour. I am not 100% sure.
The 100% charge no regen situation is slightly different. It is a hypothetical question that you do not need to worry about in real life.So I will address it in real life terms. It is a bit misleading. Yes your battery will not go from 100% to 101% then 102% because of regen once the battery is full. The effectiveness and efficiency of regen is measured against range/ battery capacity and not the against the ability to reduce the speed of your car.
So when people say regen does not work when your battery is 100% what they are saying is it will not increase battery capacity any further once it is 100%. Then comes the question will it slow down the car and when will the brake lights show? Well again it is complex again depending on the dual regenerative and hydraulic braking setup. However for this particular situation so far as slowing you car down is concerned this is what happens in real life .....
As soon as you lift your foot of the accelerator the car starts to slow down and regen will control the pace at which this slowing down occurs. The pace of regen slowing the car in turn depends on the speed at which you were driving in the non regen state, the slope of the road and the regen level you have set
So depending on the make and model of car and the factors I have mentioned above regen will not work at very low speeds eg less than 5mph but will otherwise work irrespective of the 100% charge on your charge monitor.
So yes use your brakes wisely whenever you are unsure that the brake lights have been activated but never solely because you think the car will not slow down or the brake lights will not come on because your battery monitor is showing 100%.
Remember the car is programmed to have a functional charge buffer of about 2.5 kWh so when your charging monitor says 100% the battery can still pick up charge and even in the absolute theoretical condition where this buffer is completely saturated for example after a very prolonged slow equalisation charge then the BMS in the car will protect the battery from receiving any further charge from regen but the car will slow down at a pace corresponding to the level of regen you have set all the same without adding any charge to your battery. The issue is will the brake lights come? The jury is out on this so far as the ZS EV is concerned. Some say yes others say no but I have not seen any one who has truly experienced this 100% full charge issue in real life.

 

[Kithmo]

In the Prius Hybrid, showing a full HV battery on the monitor means the battery is actually charged to 80% capacity. This and the fact that the ICE starts to charge the battery when it drops to 20% capacity is to facilitate battery longevity. Do any BEVs have this type of HV battery protection or something similar I wonder ?

 

[KasEV]

The protection gap for most EV batteries is between 2.5% to 5% of total capacity at both end at both ends.
Most reviewers believe the ZS EV has at least a 1.25kWh buffer at both ends making usable battery about capacity 42kWh. So when the battery meter says 100% the battery can still pick up to an additional 1kWh to 1.25 kWh of charge.

 

[Oldfatgit]

I frequently experience both the warning and the phenomenon. I can state categorically that the warning is displayed when the battery is fully charged and that when releasing the accelerator regenerative braking is significantly less for a while and one must apply one’s foot to the brake pedal to slow the car. One of my regular routes consists of a gentle decline for a mile at 30mph over the whole of which the regenerative braking is largely ineffective, another regular route is faster, 50 and 60 mph over the same distance and the regenerative breaking becomes effective much sooner. What I cannot state is just what the brake lights are doing, but never have other drivers been surprised by me slowing down on regenerative braking.

 

[shikoku14]

I've yet to get my ZS EV, but this sounds very familiar to what used to happen in my 24 kWh Leaf. In the Leaf you have a bubble indicator for regen level and when at 100% this would only fill up one bubble, it wouldn't take a full regen until 5-7% of the battery had been spent (really annoying as I live on a steep hill and could get a good 1% of regen from it coasting down in B mode).

Another thing to consider, is the system setup to actively get you to use the brake disks if its dectected you've been pretty much exclusively been using regen to get to a stop most of the time, to remove rust from the disks? I'm not sure if its that clever, but from experience of three EVs, the disks get pretty rusty and creaky is Autumn, Winter and Spring in the UK. Especially if you've come home in the rain and the next day set off, you need to pump the brakes a few times to stop them creaking (they sound a little ceased). I'm just wondering if MG have this warning either on detection based on data from the car, or it programtically goes off every so oftern to make sure the friction brakes are being used (sorry for what could be wild hypothesizing)

 

[Maximus]

Thanks Mgkev you are right on that - makes perfect sense.

what however does seem odd is that despite being on eco mode and kers 3 even when the battery is c50% depleted the kers reduction in speed seems much less than before. Has anyone noticed this,possibly after the software update?

Yes I had my MG first service this week Thursday, immediately noticed the reduced KERS on setting 3. Have started to use the brakes - not happy/.

 

[Phil Hayward]

Kers will be reduced if the battery is cold (below 5 C?) or fully charged, changing the kers strength will bring up a message if it is reduced

 

[Cocijo]

Yes - cold weather can also have a big impact on the amount of regen.

 

[Maximus]

Gentlemen, I have been driving my MG ZS EV for six months and when the battery is not full (which is most of the time) the regen braking worked really well even over our entire Xmas. After this Jan2022 update, it’s all most like KERS 1. Now I use brakes and miss the good old days,

 

[Deleted member 7171]

Gentlemen, I have been driving my MG ZS EV for six months and when the battery is not full (which is most of the time) the regen braking worked really well even over our entire Xmas. After this Jan2022 update, it’s all most like KERS 1. Now I use brakes and miss the good old days,

I'd go back to dealer and ask what they did.