Energy Regeneration

[Caramaddy]

The regenerative braking on an EV can be set to various levels:-

1. Hardly any regeneration, the car will coast when the accelerator pedal is released (hardly any regeneration).
2. Strong regeneration, when the accelerator pedal is released there is a strong braking effect and the brake lights come on.

If the brake pedal is pressed lightly, regeneration still occurs.

To maximize efficiency, it is recommended that the regenerative level is set to high.



My question is this: -

Do you get more regenerative energy into the traction battery by using this high setting rather than just using the brakes (GENTLY) ?

 

[Bam Bam]

The regenerative braking on an EV can be set to various levels:-

1. Hardly any regeneration, the car will coast when the accelerator pedal is released (hardly any regeneration).
2. Strong regeneration, when the accelerator pedal is released there is a strong braking effect and the brake lights come on.

If the brake pedal is pressed lightly, regeneration still occurs.

To maximize efficiency, it is recommended that the regenerative level is set to high.

I think it depends, for the reason you are hinting at with your question below.

My question is this: -

Do you get more regenerative energy into the traction battery by using this high setting rather than just using the brakes (GENTLY) ?

IF you can keep your braking at the level of regeneration then it would be more efficient to have low regeneration.

My guess is that it will depend on how precise and delicate (and therefore accurate) you can be with your foot on the brake.

If you are confident that you can brake at a rate that provides suitable regen without triggering the friction brake then this would be the most efficient.

Most of us will struggle to do that so for us it is better to use regen, and perhaps tickle the throttle when going downhill to encourage coasting and avoid unnecessary regen.

 

[Caramaddy]

I think it depends, for the reason you are hinting at with your question below.


IF you can keep your braking at the level of regeneration then it would be more efficient to have low regeneration.

My guess is that it will depend on how precise and delicate (and therefore accurate) you can be with your foot on the brake.

If you are confident that you can brake at a rate that provides suitable regen without triggering the friction brake then this would be the most efficient.

Most of us will struggle to do that so for us it is better to use regen, and perhaps tickle the throttle when going downhill to encourage coasting and avoid unnecessary regen.

You could do this, I imagine, by scanning the "Efficiency" meter on the dash - to make sure it does not reach the "bottom" of the CHARGE area. Then it will only be charging not friction braking?

Sorry if this is not clear - still unsure about terminology!

 

[siteguru]

On the MG4 we have a numbered "gauge" for energy use/regen ... white number = usage, green number = regen. Maximum green number is 25, so if you keep it in the green and below 25* then you'll always be using regen.

* Caveat - subject to battery SoC and ambient temperature.

 

[Bam Bam]

You could do this, I imagine, by scanning the "Efficiency" meter on the dash - to make sure it does not reach the "bottom" of the CHARGE area. Then it will only be charging not friction braking?

Sorry if this is not clear - still unsure about terminology!

Yeah, sorry. As @siteguru says we have the MG4 which just has a % number.

In the MG5 you've got the EV-rev-gauge version, so it sounds like that is about right. Bottom of charge area will roughly be where regen maxes out and friction bake would have to kick in.

 

[Gadget Geek]

In the ZS I've noticed that the footbrake takes no part in regenerative braking. If you look at the power meter and take your foot off the brake pedal regen kicks in, using the footbrake afrer this does not change the amount of regen.

 

[Caramaddy]

In the ZS I've noticed that the footbrake takes no part in regenerative braking. If you look at the power meter and take your foot off the brake pedal regen kicks in, using the footbrake afrer this does not change the amount of regen.

Interesting!

 

[T1 Terry]

I wish there was a method of increasing the regen braking by brake pedal pressure, rather than the mechanical braking kicking in at 25%. The Gen2 Prius does it all the way down to 16km/h, a solid stomp on the brakes will include the mechanical brakes, but generally, it's all regen ..

More questions:
25% of what, motor rated power, battery capacity, a random figure used by MG to verify it's working properly?
Does traction control also control regen to some degree? Or is this part of the reason the regen is limited to 25%?

T1 Terry

 

[Gomev]

The regenerative braking on an EV can be set to various levels:-

1. Hardly any regeneration, the car will coast when the accelerator pedal is released (hardly any regeneration).
2. Strong regeneration, when the accelerator pedal is released there is a strong braking effect and the brake lights come on.

If the brake pedal is pressed lightly, regeneration still occurs.

To maximize efficiency, it is recommended that the regenerative level is set to high.



My question is this: -

Do you get more regenerative energy into the traction battery by using this high setting rather than just using the brakes (GENTLY) ?

I'm not too sure, but how how long is that piece of string you are holding ?

 

[Caramaddy]

I'm not too sure, but how how long is that piece of string you are holding ?

Sorry, I don't follow. I am asking if it makes any difference using the brakes (gently) rather than the regeneration setting. Which is more efficient? As the brakes supply regeneration.

 

[siteguru]

Technically they don't ... what you mean is that pressing the brake pedal applies regen, until such time that the maximum regen level is achieved whereafter the physical brakes are applied. A subtle but important clarification.

I do that usually when on longer journeys - set regen to minimum (so almost coasting when lifting off the accelerator) and then apply increasing regen amounts by gently pressing the brake pedal. If I need to stop quicker then press the pedal harder.

Other people set maximum regen level and control the regen amount via the accelerator pedal. Both methods can achieve the same levels of efficiency - for me the brake method is easier to do and "feels" safer.

 

[Everest]

In the ZS I've noticed that the footbrake takes no part in regenerative braking. If you look at the power meter and take your foot off the brake pedal regen kicks in, using the footbrake afrer this does not change the amount of regen.

Isn't that because the ZS EV is an ICE vehicle adapted with a battery and motor, rather than an all-out EV design - i.e. the brakes work the same as the ICE version?

 

[Gadget Geek]

Isn't that because the ZS EV is an ICE vehicle adapted with a battery and motor, rather than an all-out EV design - i.e. the brakes work the same as the ICE version?

And why regen doesn't work in cruise control . . . they couldn't be arsed to work it out.

 

[Gomev]

Isn't that because the ZS EV is an ICE vehicle adapted with a battery and motor, rather than an all-out EV design - i.e. the brakes work the same as the ICE version?

And why regen doesn't wor

k in cruise control . . . they couldn't be arsed to work it out.

Have a look at this thread

Post in thread 'Regeneration with ACC, MG5 & MG ZS difference'

Sep 27, 2022

On my MG ZS EV 2022, when in cruise control the regen (KERS) does not seem to function when descending a hill, however I was given an MG 5 as a courtesy car today and on that one there does appear to be regeneration happening- the power display turns negative. Why the difference between the two? Will it be fixed in future software upgrades?

They use different Bosch systems, not a software issue.

• Gomev

 

[Caramaddy]

Technically they don't ... what you mean is that pressing the brake pedal applies regen, until such time that the maximum regen level is achieved whereafter the physical brakes are applied. A subtle but important clarification.

I do that usually when on longer journeys - set regen to minimum (so almost coasting when lifting off the accelerator) and then apply increasing regen amounts by gently pressing the brake pedal. If I need to stop quicker then press the pedal harder.

Other people set maximum regen level and control the regen amount via the accelerator pedal. Both methods can achieve the same levels of efficiency - for me the brake method is easier to do and "feels" safer.

Thank you for that. Using the regen facility does guarantee you are not using the friction brakes.
Efficiency, one would suppose, is very dependent on driving style more than the regenerative capacity of the car. It was interesting to read drivers' views on this - thank you.

 

[Gomev]

Sorry, I don't follow. I am asking if it makes any difference using the brakes (gently) rather than the regeneration setting. Which is more efficient? As the brakes supply regeneration.

So many variables it's almost guesswork and probably easier to work out what works best for yourself. Different cars have different set ups, amount of regen and levels of regen, when do the friction brakes take over, some individuals have heavy feet others don't, etc. etc.
I'm sure given identical set ups there will be a theoretical best, but in the meantime I'll get my ball of string and cut a piece off to measure.

 

[Caramaddy]

So many variables it's almost guesswork and probably easier to work out what works best for yourself. Different cars have different set ups, amount of regen and levels of regen, when do the friction brakes take over, some individuals have heavy feet others don't, etc. etc.
I'm sure given identical set ups there will be a theoretical best, but in the meantime I'll get my ball of string and cut a piece off to measure.

i AM WITH YOU NOW! Yes, there are a lot of variables. The way you drive is probably more important for efficiency. My MG5 is running at 3.2 miles/kW at the moment. - equivalent to 128mpg for an ICE vehicle - so I am more than happy.

It was an interesting discussion - brake or regen? You takes your pick!