Regeneration brake lights

[Tim Falkiner]

There’s a much higher amount of deceleration caused by regen KERS compared to engine braking on an ICE car.

Yes. Good point.

 

[Kithmo]

There’s a much higher amount of deceleration caused by regen KERS compared to engine braking on an ICE car.

Depends what gear you just dropped it in when changing down, second gear at speed is quite a bit of deceleration, don't ask me how I know.

 

[Tim Falkiner]

All I can say is I assumed there would be an automatic brake light as part of the KERS system and I am somewhat gobsmacked that with all the electronics this was not done. If anyone develops a system that can be retrofitted to the MGs I will be first in line.

 

[Cocijo]

My understanding (this is for the ZS) is that under certain conditions there is a brake light - this is based on rate of deceleration and in kers3. I think this was discussed and confirmed by Miles on one of the podcasts. I’ve not tested it.

 

[JodyS21]

My understanding (this is for the ZS) is that under certain conditions there is a brake light - this is based on rate of deceleration and in kers3. I think this was discussed and confirmed by Miles on one of the podcasts. I’ve not tested it.

Yep that is what was said/discussed, no one did quite the exact test that this guy has done on the 5 though - attaching a buzzer to the brake light power.
You'd think the 5 & ZS would have the same system.....

 

[Adee]

Yep that is what was said/discussed, no one did quite the exact test that this guy has done on the 5 though - attaching a buzzer to the brake light power.
You'd think the 5 & ZS would have the same system.....

Yes you would. But it doesn't. It's easy to verify yourself by applying the KERS at night by using a road sign that is intended for traffic going the other way. First check that the road sign can be seen illuminated in your mirror when you apply the brakes. Now repeat with KERS3 and no brakes. Les's test is completely definitive.
Can't believe they did this - I mean why not carry through a safety feature?

 

[JodyS21]

Yes you would. But it doesn't. It's easy to verify yourself by applying the KERS at night by using a road sign that is intended for traffic going the other way. First check that the road sign can be seen illuminated in your mirror when you apply the brakes. Now repeat with KERS3 and no brakes. Les's test is completely definitive.
Can't believe they did this - I mean why not carry through a safety feature?

I don't understand why they didn't either, it is a safety feature, but I understand it is also a legal requirement - if the rate of deceleration is greater than X the brake lights must come on.....

https://arstechnica.com/cars/2018/06/fo ... ng-ev-yet/

 

[Tim Falkiner]

Thank you for your replies.

 

[Tim Falkiner]

I don't know what actual difference this makes but IMHO a smooth ride (for both driver and passengers) is the best approach. Strong braking (whether with regen or brake pedal) makes for a less pleasant journey. I remember reading years ago that professional drivers were taught to be aware of their passengers in their peripheral vision and to make sure that their head didn't move forward as you braked or didn't take your foot gently off the brake when coming to a full stop. Driving an EV is a very different technique with the right foot, but I love it!

Agree. Though one occasion where I use a lot of regenerative braking is on streets with short, high speed humps. I take the MG ZS EV over those slowly because of the weight.

 

[Adee]

I don't understand why they didn't either, it is a safety feature, but I understand it is also a legal requirement - if the rate of deceleration is greater than X the brake lights must come on.....

https://arstechnica.com/cars/2018/06/fo ... ng-ev-yet/

View attachment 4019

Regeneration brake light

I don't know if this thread link will work for you but in my post (#30) I reported some measurements that I did with an accelerometer in the car and I showed that the deceleration in KERS3 setting can reach -0.15g which equates to just over the 1.3m/s/s that is shown in the specification that you are citing (and which I was aware of at the time). Clearly I didn't have a traceable accelerometer!

It all seems to hinge on how binding this document is to the sale of these cars in the UK market. If the document is legally valid then I would say that these cars should be provided with a regen brake light by law. However I suspect the document is not applicable in the UK?

There was insufficient feedback from members to warrant me taking it any further. I'm happy driving in KERS3 - I just adjust my style accordingly, but a recently qualified driver may not be as experienced?

 

[JodyS21]

Regeneration brake light

I don't know if this thread link will work for you but in my post (#30) I reported some measurements that I did with an accelerometer in the car and I showed that the deceleration in KERS3 setting can reach -0.15g which equates to just over the 1.3m/s/s that is shown in the specification that you are citing (and which I was aware of at the time). Clearly I didn't have a traceable accelerometer!

It all seems to hinge on how binding this document is to the sale of these cars in the UK market. If the document is legally valid then I would say that these cars should be provided with a regen brake light by law. However I suspect the document is not applicable in the UK?

There was insufficient feedback from members to warrant me taking it any further. I'm happy driving in KERS3 - I just adjust my style accordingly, but a recently qualified driver may not be as experienced?

I just found the link in some other thread, so I don't know if it is necessarily the legal requirement in the UK, the document made it sound like it was a United Nations agreement that should all should follow.
Needs further investigation.

Do we have confirmation that it is the same in the ZS?

 

[Adee]

I just found the link in some other thread, so I don't know if it is necessarily the legal requirement in the UK, the document made it sound like it was a United Nations agreement that should all should follow.
Needs further investigation.

Do we have confirmation that it is the same in the ZS?

I don't have a ZS but there seemed to be mixed messages from the thread. Some said the brake lights on a ZS worked with KERS. Others stated that the brake lights came on when in the mode where it detects the distance of the car in front (can't remember the acronym), which MG5s currently don't have. So I wouldn't say definitively, yes or no. I'm fairly sure that Teslas have this feature from what I have read - and rightly so.

The key really is whether the document has any legal footing in the UK. Or maybe there is another UK document in existence?

 

[JodyS21]

I don't have a ZS but there seemed to be mixed messages from the thread. Some said the brake lights on a ZS worked with KERS. Others stated that the brake lights came on when in the mode where it detects the distance of the car in front (can't remember the acronym), which MG5s currently don't have. So I wouldn't say definitively, yes or no. I'm fairly sure that Teslas have this feature from what I have read - and rightly so.

The key really is whether the document has any legal footing in the UK. Or maybe there is another UK document in existence?

Teslas definitely do activate the brake light if the KERS/deceleration is at a certain threshold. In fact I've seen people saying that they even get a brake light shown on their dash screens in their Teslas, so you can know for definite that it is doing it!

 

[Cocijo]

Yes - the brake lights show on the little schematic of the car on the screen. I’m not sure about legalities but it seems to be about balance as well. I find that the Tesla will show brake lights most of the time if you take your foot completely off the accelerator pedal. This can be annoying if you follow a Tesla with a driver who doesn’t do much anticipation. The ZS seems to be at the other end of sensitivity and from what I’ve read the 5 doesn’t show a brake light until the footbrake is pressed.

 

[Adee]

Yes - the brake lights show on the little schematic of the car on the screen. I’m not sure about legalities but it seems to be about balance as well. I find that the Tesla will show brake lights most of the time if you take your foot completely off the accelerator pedal. This can be annoying if you follow a Tesla with a driver who doesn’t do much anticipation. The ZS seems to be at the other end of sensitivity and from what I’ve read the 5 doesn’t show a brake light until the footbrake is pressed.

It would probably be best if all cars had brake lights that were triggered by deceleration. Most of the cars I have ever owned have had oversensitive brake light switches that require the slightest touch of the brake pedal to switch the brake lights. On the other hand this does provide a forewarning on impending (possible) braking which could save lives I suppose.

 

[Cocijo]

I think the ZS also has rapid flash warning brake lights - I think these must use a decelerometer.

 

[Adee]

I think the ZS also has rapid flash warning brake lights - I think these must use a decelerometer.

I think that is a great idea. Maybe the faster the deceleration the faster the flashing? So many opportunities for safety are missed by manufacturers. My biggest bugbear is the visibility of indicators, which they normally plonk in the middle of the light clusters. Hence less visible when the headlights or brake lights are on. Still, nobody uses them anyway, so it's a bit academic

 

[Cocijo]

This cover the haz function of the brake lights.

 

[JodyS21]

I think the ZS also has rapid flash warning brake lights - I think these must use a decelerometer.

I think the flashing brake lights for heavy/emergency braking was also mentioned in the document I found, so it’s kinda an agreed/specified feature at X threshold for car manufacturers.

 

[Cocijo]

I think the flashing brake lights for heavy/emergency braking was also mentioned in the document I found, so it’s kinda an agreed/specified feature at X threshold for car manufacturers.

It certainly should be a standard feature.