Electric vehicle queries

[raybarrow]

Hi Folks, I don't have or want an EV but, I was driving behind an electric Hyundai yesterday and his brake lights kept coming on for just a second as though he/she was just tapping the brakes, not noticebly slowing down. No queue of traffic and not hitting the speed limit. I drive a petrol auto and on downhill bits sometimes have to do this but this was a flat road. Could regenerative braking cause that or is regen braking just like dropping down a gear and letting the engine slow you down?
If electric cars have just one 'gear' with a forward or reverse option, can they go as fast in each direction? That's a scarry thought. Hopefully there would be some kind of limiter.
Ray.

[Howard]

Yes our BEV brake lights come on when regenerative braking. It has the same effect as gently pushing the brake on our ICE car.

Both our cars are automatics and, yes in theory our petrol engine car could reach a high speed in reverse if one pushed the accelerator hard. As far as I can tell they'd behave very similarly. But I haven't tested this .

regards

Howard

[Urbandreamer]

Hi Folks, I don't have or want an EV but, I was driving behind an electric Hyundai yesterday and his brake lights kept coming on for just a second as though he/she was just tapping the brakes, not noticebly slowing down. No queue of traffic and not hitting the speed limit. I drive a petrol auto and on downhill bits sometimes have to do this but this was a flat road. Could regenerative braking cause that or is regen braking just like dropping down a gear and letting the engine slow you down?
If electric cars have just one 'gear' with a forward or reverse option, can they go as fast in each direction? That's a scarry thought. Hopefully there would be some kind of limiter.
Ray.

OK:

What you noticed is a "new car" rather than EV car thing. There is a time that it takes to move your foot from the accelerator to the brake. By turning the brake lights on as someone takes their foot off the accelerator, anyone following has more time to react.

It's more prevalent in EV's, because the accelerator is also used for regenerative braking in some models and you really want the brake lights to come on with the brakes. This is known as one pedal driving.
https://www.jdpower.com/cars/shopping-g ... es-it-work

Engineering wise IC engines can only run in one direction. Steam power and electric motors (for the most part) can run in either direction equally well.
Hence, except for really old steam vehicles, limiters are fitted.

[Howard]

Hi Folks, I don't have or want an EV but, I was driving behind an electric Hyundai yesterday and his brake lights kept coming on for just a second as though he/she was just tapping the brakes, not noticebly slowing down. No queue of traffic and not hitting the speed limit. I drive a petrol auto and on downhill bits sometimes have to do this but this was a flat road. Could regenerative braking cause that or is regen braking just like dropping down a gear and letting the engine slow you down?
If electric cars have just one 'gear' with a forward or reverse option, can they go as fast in each direction? That's a scarry thought. Hopefully there would be some kind of limiter.
Ray.

OK:

What you noticed is a "new car" rather than EV car thing. There is a time that it takes to move your foot from the accelerator to the brake. By turning the brake lights on as someone takes their foot off the accelerator, anyone following has more time to react.

It's more prevalent in EV's, because the accelerator is also used for regenerative braking in some models and you really want the brake lights to come on with the brakes. This is known as one pedal driving.
https://www.jdpower.com/cars/shopping-g ... es-it-work

Engineering wise IC engines can only run in one direction. Steam power and electric motors (for the most part) can run in either direction equally well.
Hence, except for really old steam vehicles, limiters are fitted.

That's true but our BEV is not set for one pedal driving (I've tried this setting but prefer to have a similar braking effect to my petrol car. I set this three years ago when the car was new and haven't changed it). The regenerative effect, though fairly gentle, does brake the car sufficiently to illuminate the brake lights if one takes one's foot completely off the accelerator. I have noticed this in the rear view mirror whilst driving in the dark.

regards

Howard

[swill453]

What you noticed is a "new car" rather than EV car thing. There is a time that it takes to move your foot from the accelerator to the brake. By turning the brake lights on as someone takes their foot off the accelerator, anyone following has more time to react.

Are you saying that a new ICE car will activate the brake lights even if you don't press the brake pedal?

I haven't heard of that.

Scott.

[DrFfybes]

I think there is some rule coming in that if the deceleration is beyond a certain amount (Google suggests 1.3m/s2) then the brake lights come on.

So if the vehicle is using regenerative braking this level is often exceeded, and I think this was ALL vehicles (including ICE).

Alternatively the driver could just be a 'dabber' who comfort brakes even though the brakes aren't actually applied.

Paul

[Urbandreamer]

What you noticed is a "new car" rather than EV car thing. There is a time that it takes to move your foot from the accelerator to the brake. By turning the brake lights on as someone takes their foot off the accelerator, anyone following has more time to react.

Are you saying that a new ICE car will activate the brake lights even if you don't press the brake pedal?

I haven't heard of that.

Scott.

Well here is the 1989 patent, that expired in 2009 and hence could be used by all car manufacturers that have drive-by-wire, rather than throttle linkages.
https://patents.google.com/patent/US5023599

[swill453]

Are you saying that a new ICE car will activate the brake lights even if you don't press the brake pedal?

I haven't heard of that.

Well here is the 1989 patent, that expired in 2009 and hence could be used by all car manufacturers that have drive-by-wire, rather than throttle linkages.
https://patents.google.com/patent/US5023599

So is that "No, but they could in theory" then?

Scott.

[Urbandreamer]

Well here is the 1989 patent, that expired in 2009 and hence could be used by all car manufacturers that have drive-by-wire, rather than throttle linkages.
https://patents.google.com/patent/US5023599

So is that "No, but they could in theory" then?

Scott.

If you say so.

Personally I meant that I believe that the answer is yes, but can't claim that ALL cars implement the feature.

In practice ALL the equipment to do this is fitted to ALL new cars and it's entirely up to the manufacturer if they chose to turn the feature on or off in the EMU.

[swill453]

Personally I meant that I believe that the answer is yes, but can't claim that ALL cars implement the feature.

In practice ALL the equipment to do this is fitted to ALL new cars and it's entirely up to the manufacturer if they chose to turn the feature on or off in the EMU.

Do you know of any ICE cars that do this?

Scott.

[9873210]

Both our cars are automatics and, yes in theory our petrol engine car could reach a high speed in reverse if one pushed the accelerator hard. As far as I can tell they'd behave very similarly. But I haven't tested this .

ICE cars, including automatics, will (almost always) have several forward gears but only a single reverse gear. Reverse is usually as low or lower than first (forward) gear -- you can go no faster in reverse than you can in first. Try to go faster and the engine will redline, hit a rev limiter or spontaneously disassembles. Depending on the drive train the reverse speed limit might be 25 mph or so. This may seem scary fast in reverse (and the engine will be howling like a banshee) but is not quite as fast as the 100 mph or more available in top (forward) gear. Some ICE vehicles may have additional software speed limits in reverse.

Industrial and other specialized ICE equipment may have multiple reverse gears and a wider range of reverse speeds (ob joke about Italian tanks). Very rarely specialized equipment will have an independent "reverser" so all gear ratios are available in both direction and it can reach the same speed in either direction.

In comparison electric motors work (almost) equally well in both directions and differences in maximum forward and reverse speeds is entirely under software control.

My experience is with fork lifts and other industrial equipment. Comparing ICE and BEV versions. Most ICE equipment drives like a car. It's designed to move mostly in one direction. In most BEV equipment the driver's station is designed to work equally well in either direction. Some equipment will have two sets of controls so the driver can more easily face either direction. We often train BEV drivers to drive forks trailing (i.e. in "reverse") because it improves stability and perhaps braking. Note many forklifts have a maximum speed of less than 10mph, but that is still scary fast when your only 15cm from a rack.

[9873210]

Well here is the 1989 patent, that expired in 2009 and hence could be used by all car manufacturers that have drive-by-wire, rather than throttle linkages.
https://patents.google.com/patent/US5023599

The existence of a patent does not tell you if it has been implemented, would be legal if it were implemented, or indeed if it is physically possible.

I've read more than a few patents, amongst those were a few that would make an atheist pray they would never be unleashed on the public.

[airbus330]

My wife bought a Mini CooperBEV a few weeks back. The regenerative braking is quite fierce on the normal setting, so much so that it will bring the car virtually to a standstill. She was concerned that in traffic that she might get tail-ended if someone didn't quite notice that she was slowing, so asked me to follow her to see if the brake lights self activated. And indeed they do. I have not worked out if there is a threshold of retardation or time for them to be triggered, but suspect there is otherwise they would be flickering a lot as she is a bit of an on/off the gas driver.

[raybarrow]

Hi Folks,
Thanks for all that. I can see that regenerative braking brake lights are useful for those who like to drive three feet behind you. Not really an option when I slowed down by double de-clutching and changing down with no warning other than observation of traffic conditions. But in those days there was more room on the roads and it wasn't 'necessary' to tailgate so much, although impatient drivers have always been with us, sadly.
I live and learn, hopefully more of the former.
Ray,

[Arborbridge]

Hi Folks,
Thanks for all that. I can see that regenerative braking brake lights are useful for those who like to drive three feet behind you. Not really an option when I slowed down by double de-clutching and changing down with no warning other than observation of traffic conditions. But in those days there was more room on the roads and it wasn't 'necessary' to tailgate so much, although impatient drivers have always been with us, sadly.
I live and learn, hopefully more of the former.
Ray,

If you find it necessary to tailgate, remind me not to drive in front of you. Or better still, you can go by train

[redsturgeon]

I posted before about my 2018 Golf with collision avoidance braking.

After the council came and painted new double yellow lines across the front of my drop kerb, the car would perform an emergency stop at the lines when I tried to leave my driveway!

This and other inappropriate emergency stops led my to switch the system off whenever I drove.

I got rid of the car and now drive a 2009 Honda, with none of this nonsense.

[DrFfybes]

I posted before about my 2018 Golf with collision avoidance braking.

After the council came and painted new double yellow lines across the front of my drop kerb, the car would perform an emergency stop at the lines when I tried to leave my driveway!

This and other inappropriate emergency stops led my to switch the system off whenever I drove.

We do the same on our Toyota - it still bleeps at you but at least it doesn't slam the brakes on.

You Golf sounds like my mates Tesla that refused to let him reverse into the arage until he removed the tennis ball he'd hung from the roof to tell him when to stop

Paul

[y0rkiebar]

We recently collected a new campervan based upon a Fiat Ducato. This is a Euro 6 diesel and uses the smart alternator to slow the vehicle in certain circumstances (lifting the accelerator, dialing down the cruise control speed etc). Not sure if this triggers the brake lights, will have to get someone to follow.

[DrFfybes]

We recently collected a new campervan
[....]
Not sure if this triggers the brake lights, will have to get someone to follow.

Yeah, I'm sure that won't be a problem

Paul (recently relocated from Devon).

[y0rkiebar]

Yeah, I'm sure that won't be a problem

Paul (recently relocated from Devon).

Actually this one is pretty nippy and is a panel van conversion so not some huge megabus.