electric cars and frosty roads

[Andrew]

And changing down in an EV car is a bit tricky when most (all ?) only have one gear.

[NY]

The issue is that an electric car running at a speed that would entail top gear in a petrol/diesel car should not slow down any more quickly when you lift off the accelerator that a petrol car would - until you press the brake pedal when a suitable combination of frictional and regenerative braking should be used. A car which "braked" any more fiercely than this would require a very different style of driving because you'd have to keep your foot partially on the accelerator as you approached a junction so it slowed down more gently than if the regen brakes kicked in as soon as you lift off the power. And as the OP said, it is positively dangerous if the wheels get braked if you lift off because of a skid.

I'm trying to remember the last time any of my FWD cars experienced a rear-wheel skid. FWD skids are more common (though still very rare!) if you enter a bend, steer to follow it and the wheel (at and angle) continue to skid straight. I've had that happen very occasionally at very slow speed on an icy road, and the remedy is to come off the power and wait for the wheels to start biting again so the car once again follows the course you've steered.

No car should change down or apply anything more than light engine/motor braking if you simply lift off the power; it should require positive action like pressing the brake pedal before changing down or regenerative braking happen.

[Andy Burns]

The only ones I've seen which have gears are the classic car conversions of e.g. E-type, Beetle where they wanted to do the minimal changes (see Bobby Llewellyn)

[Tim+]

Change that to ?no car should unintentionally...? and I might agree. In normal non-slippery conditions ?one-pedal? driving in an EV in town can be a useful facility with highish levels of regenerative braking available on the overrun. Saves a lot of foot dancing between pedals. So, there are times when it?s a useful feature.

As far as I?m aware, it?s always a driver selectable option.

Tim

[Dave Liquorice]

There is naff all engine braking in my car until you get down to 4th,

5 and 6 are over drives.

I think a lot is down to anticipation of what your expect to happen as you lift of the accelerator. Like the strange sensation of acceleration the first few times you take your foot off when you've engaged cruise control. You expect to slow down but you remain at the cruise speed which is perceived as accelerating. You soon get used to it though, just as you get used to the varying amounts of engine braking in each different gear.

[Dave Liquorice]

IIRC "winter" tyre compounds are high silica and supposed to remain softer at low temps, below 7 C is often quoted. They are also supposed to wear quicker in the summer but I can't say I've noticed. First set of winters I had I'd take off in the summer until the end of their third maybe fourth winter when they were starting to not perform quite as well but still had a good few thousand miles left. Kept them on for the summer no noticeable difference in wear rate...

[polygonum_on_google]

I think you are overstating there with "No car".

My car has adaptive cruise control. It can go into a coasting mode. It can apply braking. Very obvious if you set it to something like 50 on an up and down road. So simply lifting your foot off the power can brake quite hard if you are going faster than the ACC is set and downhill. Almost unnoticeable if fairly level and ACC speed is what you are doing.

[Dave Plowman (News]

I'm sure when you're struggling for range, regeneration is preferable to braking. But then the same applies to any vehicle. If you brake when not actually needed you'll use more fuel.

However regenerative braking is still more inefficient than 'coasting' to a stop.

[The Natural Philosopher]

But you have no clutch so left foot braking is surely the norm?

[Tim Lamb]

Following what I assume to be automatics down relatively shallow slopes, it is common to see the brake lights coming on a intervals.

I vaguely assumed 4th on my 5 ratio manual box was providing more engine braking than that available on an automatic.

[Andy Burns]

Do you left-foot break in an automatic? I don't.

[charles]

I don't, but then I've drive manual box cars for 50+ years befoer getting an auto.

[Dave Plowman (News]

Why would that be any different to a manual?

If the car is gaining speed downhill with zero throttle, many autos will drop a gear or two on a touch of the brakes.

[Dave Plowman (News]

I learned to left foot brake on my first auto getting on for 50 years ago. It had rather peculiar brakes - a mechanical servo. At very low speeds no servo action which then came in when the car moved. But also had direct mechanical connection to the rear brakes from the foot pedal - same as the handbrake. But the handbrake was in an awkward place for manouvering. So much easier to use the left foot on the pedal which did much the same as the handbrake.

Never had a problem swapping back to a manual. Although could be different if I started left foot braking at my present age.

[The Natural Philosopher]

oh yes. Always. How else can you inch forwards? Do a hill start? Do a rapid take off? force the thing to kickdown mid corner slowing down?

I treat it like a clutch when taking off and a brake when slowing down.

Its just another thing to learn.

[NY]

It should certainly be driver-selectable if it is present. I wouldn't want it to happen unless I was expecting it to happen. It's not how petrol/diesel cars behave and I would not *expect* an electric car to behave any differently because I would want to drive it the same: right foot for accelerator and brake, left foot for clutch in a manual (petrol/diesel), otherwise not used. Lifting off the power to brake is a very different behaviour and one which requires a very different driving style.

[Tim Lamb]

In message [e-mail]>, "Dave Plowman (News)" [e-mail]> writes

I didn't know auto boxes would drop a gear. I did my *nose on the windscreen learning* in America as the hire place did not have anything with a manual shift. 1985 and not driven one since.

[Tim+]

You misunderstand. All EVs use regeneration when using the brake pedal until you require more braking than regen can provide on its own, at which point the brake pads are called into action. You can?t normally turn this off. Consequently you do get regenerative gains in normal driving.

The only controllable regeneration is that which occurs on the over-run. Some EV owners incorrectly seem convinced they need to keep this setting on max for maximum economy. In hilly country where you?re coming on and off the throttle frequently high regen settings can make driving easier as you?re less likely to need to shuffle you foot twixt throttle and brake.

Indeed. Anticipation and smooth driving are key.

Tim

[Tim+]

Not when I also drive a conventional manual occasionally. My brain can?t cope with transition. Additionally, I also have the option of braking by hand using a paddle control to maximise regen.

Tim

[Tim+]

Take my foot off the brake.

Auto handbrake

Stomp the accelerator.

Kickdown? How quaint. ;-)

Yeah, I?ll admit that left foot braking is probably a useful skill in some autos but It?s lovely not needing all that mechanical nonsense anymore. Still, each to his own.

Tim