Brake lights with regen...

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RegGuheert

Well-known member
Joined
Mar 19, 2012
Messages
6,419
Location
Northern VA
I generally have a concern that if I am slowing rapidly that those behind me should have some warning. Others here have expressed that they use D when in traffic so that they will have to use their brakes to slow down in traffic, thus warning drivers behind them.

Given this, perhaps it makes sense to also have the brake lights come on beyond a certain level of regenerative braking, even if the driver does not have their foot on the brake pedal. That seems to match the intent of the brake lights.

Perhaps it could come on beyond 25 kW of regeneration and go off below about 20, giving it a fair amount of hysteresis so that it does not flicker on and off to quickly.

I can imagine this might eventually become a requirement as future EVs may have significantly more regenerative braking power than the current crop.

Thoughts?
 
RegGuheert said:
I can imagine this might eventually become a requirement as future EVs may have significantly more regenerative braking power than the current crop.

Thoughts?
The ActiveE does this. Not 100% sure about the Tesla Roadster, but I think it uses brake lights on regen as well. It's worth noting however, that when you let go of the accelerator pedal, both vehicles slow down much more aggressively than the Leaf in ECO mode. Check out a recent discussion on this topic in the ActiveE Facebook group
 
For our purposes, I'm happy with the current behavior. In the mountains where we do most of our driving, having brake lights on ECO mode regen could be overkill and annoying, at least with the current level of regen. In ICE cars, drivers control speed on downgrades by downshifting, or in the case of the Prius, by using "B" mode, which does not turn on the brake lights.

On the other hand, a 20-25 kW brake light threshold might be helpful in more urban/suburban contexts, i.e., at signals and in traffic.

Adding a "B" mode, possibly with even stronger regen for downgrades, would be a reasonable way of making this selectable.
 
abasile said:
Adding a "B" mode, possibly with even stronger regen for downgrades, would be a reasonable way of making this selectable.
Yes, I love that idea. While at it, they should also get rid of the creep or allow us to deactivate it. Leaf's brake lights are really high up, and I've noticed that they are shining directly into the faces of folks stopped behind me at a red light. I often put the handbrake on, so that I don't continue to blind them. In the ActiveE, I don't have to ride the brakes thanks to the strong regen. Not even at a full stop, since there is no creep. Yes, it takes some time getting used to, but you don't want to go back after that.
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[youtube]http://www.youtube.com/watch?v=1d7uqB2OYYY[/youtube]
 
Logically, the brake lights should come on at some level of deceleration, regardless of the cause (brakes, regen, blended). Accelerometers are cheap and robust these days so it would seem reasonable to use them to trigger the brake lights.

On the other hand, the LEAF's regen is mild enough to where I don't think it presents a problem for following motorists. It's certainly no more intense than even a 4-cylinder manual transmission ICE using engine braking.
 
Nubo said:
Logically, the brake lights should come on at some level of deceleration, regardless of the cause (brakes, regen, blended). Accelerometers are cheap and robust these days so it would seem reasonable to use them to trigger the brake lights.

On the other hand, the LEAF's regen is mild enough to where I don't think it presents a problem for following motorists. It's certainly no more intense than even a 4-cylinder manual transmission ICE using engine braking.
No need for an accelerometer. I think some previous car (AC Propulsion's T-Zero?) simply knew when the motor was slowing down since its RPM is constantly monitored and turned on the brake lights when some deceleration threshold was reached. I'm sure the Leaf is actively monitoring RPM too.
 
I'm sure the Leaf has several accelerometers already, used by the air bags and ABS system... it would be nice if Enginier modded the regen out of the gas pedal and into the brake pedal where it belongs, then you would not have to worry about the brake lights.
 
Herm said:
I'm sure the Leaf has several accelerometers already, used by the air bags and ABS system... it would be nice if Enginier modded the regen out of the gas pedal and into the brake pedal where it belongs, then you would not have to worry about the brake lights.

Funny, I'm waiting for him to mod the regen out of the brake pedal and put everything on the gas pedal where it belongs ;)

BTW, the cruise control uses what regen is available on the gas pedal, so less regen available for the CC in D than in eco. If you mod all the regen out from the gas pedal, CC won't be able to use any regen at all and thus rendering itself useless.
 
jkirkebo said:
Funny, I'm waiting for him to mod the regen out of the brake pedal and put everything on the gas pedal where it belongs ;)

I'm not going to criticize you for wearing out the battery prematurely or wasting power.. for all I know you may have a photovoltaic system :)

Good point on the cruise control.. perhaps Enginier can put a 3 way switch on his mod. I would like a momentary switch on the steering wheel to disable regen, or perhaps just drop the car into neutral, back to drive when the switch is released.

Some would say if you need to use the brakes you are driving too fast for the local conditions.
 
Herm said:
Some would say if you need to use the brakes you are driving too fast for the local conditions.
Try going down the many hills and mountains out here without brakes... :eek:

Glad there's enough A-pedal regen that I don't have to ride the brake pedal on those descents, though.
 
surfingslovak said:
[youtube]http://www.youtube.com/watch?v=1d7uqB2OYYY[/youtube]

I think no creep would be interesting to have, in conjunction with a really a really strong regen. I wish that Drive had no regen on the A pedal and Eco had even stronger regen from the A pedal. But that's my personal preference.

As far as the car turning off if I open the door - I absolutely do not like that. Not knowing all of the circumstances that the Active-E turns itself off if you open the door, there have been many times where I put the car in park, hop out to grab something and come back in and go - all with my wife in the car and the radio and air on. I think the LEAF does a fine job of beeping at me and showing me warnings when I leave the car with it left on.

Or if you realize that your door is not closed all the way (that point of partial closure when the car indicates the door is open) and you attempt to open and shut your door... does it turn off then?
 
Nubo said:
Logically, the brake lights should come on at some level of deceleration, regardless of the cause (brakes, regen, blended). Accelerometers are cheap and robust these days so it would seem reasonable to use them to trigger the brake lights.

On the other hand, the LEAF's regen is mild enough to where I don't think it presents a problem for following motorists. It's certainly no more intense than even a 4-cylinder manual transmission ICE using engine braking.

I don't think we should switch brake lights from pedal input to accelerometer, I was always using brake light to warn the drivers behind me that there's something coming up front by touching brake pedal, so I can "touch" the brake before actually starting to decelerate, giving more time to react for the driver behind you.
 
I really dislike creep in an EV and wish I could switch it off. The first time I drove one with creep it really surprised me as I did not expect it! It seems to be nothing more than a way to make people think they are driving a "conventional" car... It is particularly annoying to me since I am used to manual transmissions...

EricBayArea said:
I think no creep would be interesting to have, in conjunction with a really a really strong regen.
 
abasile said:
Herm said:
Some would say if you need to use the brakes you are driving too fast for the local conditions.
Try going down the many hills and mountains out here without brakes... :eek:

Glad there's enough A-pedal regen that I don't have to ride the brake pedal on those descents, though.
I wish that were true on my hills. I'd like about 50% more regen in Eco (or equivalent setting) to keep my speed under control without having to use the Brake pedal.

The idea of having the brake lights come on when the motor is slowing by a certain amount seems like a good idea. When traveling downhill on regen at a constant velocity brake lights would be off, as they should be. When actually slowing they would be on.
 
UkrainianKozak said:
Nubo said:
Logically, the brake lights should come on at some level of deceleration, regardless of the cause (brakes, regen, blended). Accelerometers are cheap and robust these days so it would seem reasonable to use them to trigger the brake lights.

On the other hand, the LEAF's regen is mild enough to where I don't think it presents a problem for following motorists. It's certainly no more intense than even a 4-cylinder manual transmission ICE using engine braking.

I don't think we should switch brake lights from pedal input to accelerometer, I was always using brake light to warn the drivers behind me that there's something coming up front by touching brake pedal, so I can "touch" the brake before actually starting to decelerate, giving more time to react for the driver behind you.

No, I certainly wouldn't recommend removing the brake pedal switch. When I take over the world you'll still be able to do that.
 
jkirkebo said:
Herm said:
I'm sure the Leaf has several accelerometers already, used by the air bags and ABS system... it would be nice if Enginier modded the regen out of the gas pedal and into the brake pedal where it belongs, then you would not have to worry about the brake lights.

Funny, I'm waiting for him to mod the regen out of the brake pedal and put everything on the gas pedal where it belongs ;)

I'm not being facetious -- what I REALLY want is a "trim wheel" to control regen. That would let me dial in just the right amount to control speed on long downhills, etc..
 
Nubo said:
Logically, the brake lights should come on at some level of deceleration, regardless of the cause (brakes, regen, blended). Accelerometers are cheap and robust these days so it would seem reasonable to use them to trigger the brake lights.
All this talk about needing brake lights when using ECO is worrying me about the skillset of drivers. Does anybody drive with a stick shift anymore? Trucks and many standard transmission drivers (such as myself) use the gears to slow the car down all the time. I've never heard of someone being rear ended while using the lower gears, except when road conditions were icy and the trailing car was going too fast. There are a lot more incidents of people using brakes on bad road conditions and losing control of their car.

An engine slows the car down moderately. One should not need brake lights to tell that they are going faster than the car ahead of them and be able to slow down in plenty of time. If people are only looking for brake lights as an indication to slow down, I think there would be a lot more accidents on the road.
 
About six years ago I installed the Azure Dynamics/Solectria A/C electric drive system in a Porsche 914. The DMOC controller was user programmable for regen parameters and an electric signal was provided to activate the brake lights on regen of a certain level. My gentle driving needed this signal because as an old Formula Vee driver I rarely used the brakes. I'm pleased with regen in ECO on my LEAF although I'd like to dial it up too.

I not so much of a purist; I like the creep feature for maneuvering carefully out of tight parking.
 
+1!

padamson1 said:
All this talk about needing brake lights when using ECO is worrying me about the skillset of drivers. Does anybody drive with a stick shift anymore? Trucks and many standard transmission drivers (such as myself) use the gears to slow the car down all the time.
 
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