Regeneration brake lights

[Jeff]

Still do not know if the brake lights should come on under heavy regeneration,asked the dealer and got mixed message. Always drive in eco mode with full regeneration.worried I will be rear ended

 

[Jomarkh]

Still do not know if the brake lights should come on under heavy regeneration,asked the dealer and got mixed message. Always drive in eco mode with full regeneration.worried I will be rear ended

Hi, i cant remember what the title was but Les did a great test about this. Basically no brake lights

 

[Les burrows]

Hi Jeff here is the test that Jomarkh wrote about that I did with my MG5 you don’t say which MG car you have but there is a thread called Regeneration brake lights which I’m sure is one that you started in May 1st 2021 same subject there is around 5 pages of comments on there
Sometimes I do not understand how this forum works in this regard same subject with more than one thread I have notice this on more than on this subject so I have copied below the test that I ran and what I found a few weeks back this was #44 in the other thread and read the comments there I tried every which way under normal day to day driving Conditions I’m convinced no they do not work and I don’t believe anything that a lot of dealers say anymore

Les burrows​

Premium Member
JoinedDec 15, 2020Messages292Reaction score242Points46Age74 WiganDrivingMG5 EV

• Jun 10, 2021
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• #44

DO BRAKE LIGHTS WORK IN REGEN? NO THEY DO NOT
Hi everyone just flicking trough so old threads on the forum yesterday and came across this one again about do the brake lights come on when the car is in regen
Well I can only speak for what I have found out today in my own MG5

This is what I did this morning I removed the cover for the high level brake light from inside the tailgate got at the wiring for the said light and connected an extra cable to it I then ran the cable through the car and connected a small beeper to the other end so now every time the brake light operates the beeper goes off and than went for drive to do some tests and this is what I found

1 the brake lights only work in TWO ways only, they come on when you press the footbrake (obviously) and the only other time they are on is when the GREEN (P) is ALIGHT in the dash, that’s when the auto hold button is alight the one marked (A) then the brake lights stay on until you move off again or select P when the parking brake is on in the dash there is a (P) in RED this is like the handbrake and the brake lights or not on in this mode

So to comfirm
I drove the car for several miles with this bleeper set up and tried every mode possible from 10-60 MPH and no matter if it was in Eco / Normal/or Sport and no matter which KERS setting I used in any of the modes the brake lights do not come on unless you use the foot brake in KERs 3 from almost 70 I took my foot off the pedal to get as much regen as possible still nothing from the bleeper
So Brake Lights Do Not work in Regen 1/2/or3
Pictures below
1 inside off tailgate high level brake light cover
2 cover removed
3 wiring and plug for high level brake light
4 extra cable now attached
5 sound beeper on sunvisor
Could have use a light bulb but the sounder was for better in daylight
Hope this answers some of the questions in the thread
As I said mine is the MG5
Les

Last edited: Jun 11, 2021
Jun 11, 2021

 

[Adee]

No, the brake lights don't work under max regen (KERS3). They should. The end.

My best advice is that if you want to use KERS3 (and I do all the time), then aim to anticipate traffic conditions so that you can feather the accelerator rather than taking your foot right off it. This way the car behind does not get taken by surprise. Not always possible I agree, but it's the best compromise if you want to take maximum advantage or the regeneration.

 

[Kithmo]

My best advice is that if you want to use KERS3 (and I do all the time), then aim to anticipate traffic conditions so that you can feather the accelerator rather than taking your foot right off it. This way the car behind does not get taken by surprise. Not always possible I agree, but it's the best compromise if you want to take maximum advantage or the regeneration.

You should be doing that anyway, that's the reason the mirror holds such importance in the driving test, not for checking your makeup as many think.

 

[5teep]

not for checking your makeup as many think.

Well damn!

 

[Adee]

You should be doing that anyway, that's the reason the mirror holds such importance in the driving test, not for checking your makeup as many think.

Couldn't disagree with that. Luckily my looks are well beyond anything that makeup could ever hope to rectify, so it gets used for the correct purpose of checking whether the grandchildren have nodded off in the back so we can stop the car and get a few minutes peace and quiet.

 

[Cocijo]

It’s important to look good...

 

[Kithmo]

It’s important to look good...

Too late for me

 

[JodyS21]

Wow just come across this, I usually only look in the zs forum.
There was some discussion I remember and there was some text quoted from the legal requirements, it stated something like the brake lights must illuminate if the rate of speed decrease is over X amount.
I’d have thought in regen 3 at max amount it would be enough of a speed decrease to need to trigger the brake lights, but it’d need proving obviously.

 

[PaulWaun]

Why would the brake lights come on under regen? Surely KERS is the equivalent of engine braking in an ICE vehicle and brake lights don’t come on in a petrol/diesel if you take ur foot off the accelerator

 

[JodyS21]

Why would the brake lights come on under regen? Surely KERS is the equivalent of engine braking in an ICE vehicle and brake lights don’t come on in a petrol/diesel if you take ur foot off the accelerator

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

 

[SimonomiS]

Yes, though it all depends on your right foot of course. If you're very gentle reducing the pressure it's very different from taking your foot completely off!

 

[PaulWaun]

Yes, though it all depends on your right foot of course. If you're very gentle reducing the pressure it's very different from taking your foot completely off!

Exactly, ur just as likely to get rear ended by braking hard and late in an ICE. Anticipate more and ease off slowly earlier

 

[JerryCollinsDM]

Why would the brake lights come on under regen? Surely KERS is the equivalent of engine braking in an ICE vehicle and brake lights don’t come on in a petrol/diesel if you take ur foot off the accelerator

If you don't have an EV you won't appreciate the difference it makes! I drive a 5EV and a Kia diesel and I have to readjust my driving style quite a bit between the two cars, even at KERS 2.

I saw a post from a Tesla driver who had racked up a decent mileage (I forget how much, but 30K+), and he was amazed by how little his brake pads had worn due to regen braking rather than friction braking.

I definitely believe the brake lights should operate at max regen!

 

[JodyS21]

Yes, though it all depends on your right foot of course. If you're very gentle reducing the pressure it's very different from taking your foot completely off!

I try to maximise all the regen I can, seems crazy not to, so my general driving style is:
When I want to come to a stop/slow down etc.
At the appropriate time/distance before need to stop etc.
I lift completely off the accelerator, let the regen do as much as it can for a few seconds and then press the brake pedal to get some friction braking as is necessary to stop etc.

If I can avoid using the brake pedal I do, no point engaging any friction braking if it’s not necessary.
I guess pressing the brake pedal a tiny tiny amount won’t be enough to start triggering any friction braking, but should be enough to trigger the brake lights. Maybe this is how it is best to drive it.

 

[PaulWaun]

In that case I guess the question is, does taking ur foot off last second (exagerrated) for a short period of max regen put more or less back into the battery as less regen but for longer, i.e. easing off earlier

 

[SimonomiS]

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!

 

[Rabmc]

I personally have found that lifting off early using regen 1 and switching it into regen 2 as I approach the junction/roundabout, if I need it, makes for a smooth journey and also seems to give slightly better miles/kwhr

 

[Dt99idr]

Even if you use the brake pedal the car is still doing regeneration unless you slam the breaks on or are at very slow speed. KERS just gives you a choice over how quickly you want the car to slow down when you lift off the accelerator. (Assuming your battery isn't full)