EV Retardation - Dangerous?
Discussion
I've seen many electric cars on the road and I'm aware they have higher levels of retardation (setting myself up for something here I feel) due to their regen systems but last night I was following a brand new I-Pace and then drop off in speed was crazy. I felt like I really had to be on my toes when following in traffic.
It was night/raining which didn't help and I know some of you will say you should focus on the car in front of you all the time but you know how it is really.
It was slowing down a lot faster than it would've if they used the brake pedal in a normal fashion which got me thinking it wouldn't be a bad idea to have a small flashing red light when slowing down under the regen system a bit like the ERS charging light in F1.
I felt like it was asking for an accident when someone who sits on their phone/does make up etc in traffic are following.
It was night/raining which didn't help and I know some of you will say you should focus on the car in front of you all the time but you know how it is really.
It was slowing down a lot faster than it would've if they used the brake pedal in a normal fashion which got me thinking it wouldn't be a bad idea to have a small flashing red light when slowing down under the regen system a bit like the ERS charging light in F1.
I felt like it was asking for an accident when someone who sits on their phone/does make up etc in traffic are following.
Couldn't agree more. I drive a Leaf and it really should illuminate the brake lights when in regen. The number of times I've been convinced someone is going to smash me up the trumpet is daft. People who have never driven an EV (i.e. nearly everyone still) have no idea, and that isn't their fault - it's a risk which really should be mitigated by EV manufacturers.
All of the above (as far as I'm aware, certainly the Jag) will illuminate brake lights when the deceleration exceeds a certain threshold (this is a regulatory requirement) - I don't remember the figure off the top of my head but say 0.2g of decel.
Yes that threshold is slightly higher than what most people will experience in engine braking lift-off in an automatic, but downshifting in a manual can generate greater retardation without any brake lights.
Yes that threshold is slightly higher than what most people will experience in engine braking lift-off in an automatic, but downshifting in a manual can generate greater retardation without any brake lights.
SuperPav said:
All of the above (as far as I'm aware, certainly the Jag) will illuminate brake lights when the deceleration exceeds a certain threshold (this is a regulatory requirement) - I don't remember the figure off the top of my head but say 0.2g of decel.
Yes that threshold is slightly higher than what most people will experience in engine braking lift-off in an automatic, but downshifting in a manual can generate greater retardation without any brake lights.
Exactly this.Yes that threshold is slightly higher than what most people will experience in engine braking lift-off in an automatic, but downshifting in a manual can generate greater retardation without any brake lights.
The main problem seems to be people travelling too close and not paying attention...
I think we've probably just got accustomed to all the idiots in normal cars who press the brake pedal to slow slightly when they don't actually need to use the brakes, so have come to expect brake lights every time a car reduces speed at all.
"Crying Wolf" braking is particularly bad on motorways, and seems to be a feature of pretty much Hyundai Tucson driver I've been behind(other boring pretend 4x4s which unnecessarily obstruct the view of the road in front are also available). Eventually they have to genuinely brake, and then wonder why the car behind runs into them.
For some reason, the same people also seem unable to read matrix signs unless their foot is resting on the brake pedal....
"Crying Wolf" braking is particularly bad on motorways, and seems to be a feature of pretty much Hyundai Tucson driver I've been behind(other boring pretend 4x4s which unnecessarily obstruct the view of the road in front are also available). Eventually they have to genuinely brake, and then wonder why the car behind runs into them.
For some reason, the same people also seem unable to read matrix signs unless their foot is resting on the brake pedal....
SuperPav said:
All of the above (as far as I'm aware, certainly the Jag) will illuminate brake lights when the deceleration exceeds a certain threshold (this is a regulatory requirement) - I don't remember the figure off the top of my head but say 0.2g of decel.
Yes that threshold is slightly higher than what most people will experience in engine braking lift-off in an automatic, but downshifting in a manual can generate greater retardation without any brake lights.
This is exactly what I was thinking should exist, so if it already does that's great.Yes that threshold is slightly higher than what most people will experience in engine braking lift-off in an automatic, but downshifting in a manual can generate greater retardation without any brake lights.
Of course it's the type of system that won't be designed to fail-closed, so it keeping working is reliant on sensors etc. Devil's advocate - the Jag OP mentioned could have had a faulty or badly calibrated system.
Perhaps should be part of the MOT to check this, though would be a bit of a bugger for testers. Small sensor strapped to brake light that lets out a piercing scream when they illuminate?
DDg said:
I borrowed an i3 for a day and thought exactly the same GMG. Whereas I’m used to seeing traffic ahead, taking my foot off the accelerator to slow to match their speed by the time I reach them, with the i3 it was difficult. It was either take my foot off, experience rapid retardation with the brake lights activating, then correct with accelerator, or get the timing right, driving up to them then letting off with the same brake lights. Either way it was too much brake light for me. Yet it felt unnatural to feather the throttle to slow without brake lights - a fine balancing act.
Maybe I’d get used to it but it bugged me.
Unlike in an ICE car, you don't take your foot off the accelerator completely when trying to come to a gentle stop, you modulate the position of the accelerator pedal to get the desired amount of regen braking. Brake lights do come on.Maybe I’d get used to it but it bugged me.
Once you get used to it, having to use the brake pedal to stop in an ICE car will feel archaic!
On cars with active cruise control brake light activation is uncoupled from pressing the brake pedal. Not having any indication of when the brake lights are on is one of the things I don't like about the system in my Golf. On a motorway a quick flash of brake lights of the car in front used to mean it was probably cancelling cruise but now with ACC you don't need to do that.
Caddyshack said:
I am about to fit a smart sensor designed for motorbikes to my Renault Twizy as the brake lights do not come on with that on regen and with the regen adjusted up it can really brake hard.
You can fit them to any car and they do a discount for referals if anyone wants to get one
I was going to suggest the same. Most motorcycles have a very strong engine braking effect in comparison to a car, and it is perfectly possible to ride around a town or city with very little use of the brakes unless coming to a complete halt. Similarly, reducing speed from NSL to a 30, for example, is easily done with no use of the brakes at all, at a rate which would definitely require use of the brakes in a car.You can fit them to any car and they do a discount for referals if anyone wants to get one
My instructor was an advocate of using the rear brake pedal to operate the brake light in situations where you might be vulnerable to a rear end impact. In an EV, this is obviously less practical.
I have experienced this the other way around... In normal traffic conditions my engine braking is a lot less than most cars around me. In town driving my engine is barely idling at 800rpm and the car has a lazy slush box. So, a hatchback doing 2-3k rpm with a manual gearbox has significantly stronger engine braking.
So when I bought my current car I had a period of adjustment, I think I now leave a bigger gap and use the service brakes a lot more. I get tailgated more as a result!
If you are finding the same when following electric cars, you'll probably automatically adjust over time unless you are a habitual tailgater.
Shaoxter said:
DDg said:
I borrowed an i3 for a day and thought exactly the same GMG. Whereas I’m used to seeing traffic ahead, taking my foot off the accelerator to slow to match their speed by the time I reach them, with the i3 it was difficult. It was either take my foot off, experience rapid retardation with the brake lights activating, then correct with accelerator, or get the timing right, driving up to them then letting off with the same brake lights. Either way it was too much brake light for me. Yet it felt unnatural to feather the throttle to slow without brake lights - a fine balancing act.
Maybe I’d get used to it but it bugged me.
Unlike in an ICE car, you don't take your foot off the accelerator completely when trying to come to a gentle stop, you modulate the position of the accelerator pedal to get the desired amount of regen braking. Brake lights do come on.Maybe I’d get used to it but it bugged me.
Once you get used to it, having to use the brake pedal to stop in an ICE car will feel archaic!
TX.
One pedal driving, seems to be me, smoother and safer way to slow down a car.
I understand the deceleration curve is computer assisted? So a small update could fix it.
Not sure about ipace, but tesla regen braking is recently updated and is now very smooth.
Also the brake light is designed to emulate ICE behaviour so ideally you shouldn't notice a different.
I think
I understand the deceleration curve is computer assisted? So a small update could fix it.
Not sure about ipace, but tesla regen braking is recently updated and is now very smooth.
Also the brake light is designed to emulate ICE behaviour so ideally you shouldn't notice a different.
I think
Terminator X said:
Shaoxter said:
DDg said:
I borrowed an i3 for a day and thought exactly the same GMG. Whereas I’m used to seeing traffic ahead, taking my foot off the accelerator to slow to match their speed by the time I reach them, with the i3 it was difficult. It was either take my foot off, experience rapid retardation with the brake lights activating, then correct with accelerator, or get the timing right, driving up to them then letting off with the same brake lights. Either way it was too much brake light for me. Yet it felt unnatural to feather the throttle to slow without brake lights - a fine balancing act.
Maybe I’d get used to it but it bugged me.
Unlike in an ICE car, you don't take your foot off the accelerator completely when trying to come to a gentle stop, you modulate the position of the accelerator pedal to get the desired amount of regen braking. Brake lights do come on.Maybe I’d get used to it but it bugged me.
Once you get used to it, having to use the brake pedal to stop in an ICE car will feel archaic!
TX.
I've an EV and an ICE, I can confirm that it does feel archaic getting in my ICE after driving the EV. ICE is a technology which is becoming obsolete, and in comparison to the latest drivetrain types it is indeed old-fashioned.
Sorry, Grandad.
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