Technique for stopping/continuing on uphill slope?

[KeithFrechette]

In the section "Driving Vehicle" in the LEAF owner's manual, there exists the following caution.

CAUTION
When stopping the vehicle on an uphill slope, do not hold the vehicle by depressing the accelerator pedal. The foot brake should be used for this purpose.

Is using the foot brake enough to prevent rollback? For instance, when stopped on a slope at a traffic light or stop sign, what's the recommended way to ensure that the vehicle doesn't roll backward during takeoff? I would ordinarily use the accelerator (and clutch, in a manual transmission vehicle) to "balance" the vehicle's motion, but it sounds like this isn't recommended/needed for the LEAF.

Thanks.

-- Keith

 

[davewill]

Is using the foot brake enough to prevent rollback? For instance, when stopped on a slope at a traffic light or stop sign, what's the recommended way to ensure that the vehicle doesn't roll backward during takeoff? I would ordinarily use the accelerator (and clutch, in a manual transmission vehicle) to "balance" the vehicle's motion, but it sounds like this isn't recommended/needed for the LEAF.

I have yet to notice any tendency to roll backwards when moving from the brake to the accelerator on a hill. I'm beginning to think that the car has been engineered not to. I do know that if you're starting uphill from a parked situation that you can leave the parking brake engaged and simply press the accelerator. The parking brake will automatically disengage and off you go.

 

[derekjsmith]

e-brake auto release as a anti rollback

 

[KeithFrechette]

That seems sensible, and that's what I was originally expecting, but I must admit that the information in the manual seemed self-conflicting.

DRIVING THE VEHICLE
NOTE: The electric parking brake will automatically be released, when you depress the accelerator while the vehicle is in the D (Drive) position, ECO position or R (Reverse) position with the seat belt fastened.

WARNING
Be sure the electric parking brake is released before driving. Failure to do so could cause brake failure and lead to an accident.

NOTE: Do not start driving while the parking brake is applied. Doing so may cause the parking brake to overheat or reduce its effectiveness, which could result in an accident.

However, on closer inspection now, there seem to be more references that support accelerating with the electric parking brake engaged (and letting it automatically disengage) than there are references to the contrary.

-- Keith

 

[kovalb]

The owner's manual still has a lot of boilerplate left over from ICE vehicles. The LEAF can be held on a hill using the accelerator pedal only, or by engaging the electric parking brake and permitting it to auto release on take-off. It's all good.

 

[DaveEV]

Is using the foot brake enough to prevent rollback? For instance, when stopped on a slope at a traffic light or stop sign, what's the recommended way to ensure that the vehicle doesn't roll backward during takeoff? I would ordinarily use the accelerator (and clutch, in a manual transmission vehicle) to "balance" the vehicle's motion, but it sounds like this isn't recommended/needed for the LEAF.

Ouch. That's not the recommended way to hold your position in a regular car, either. Your poor clutch/transmission! Brakes are for holding the car in place. You should only use the accelerator when you want to start moving.

 

[KeithFrechette]

It was when *I* was learning to drive (in the mid-80's), and I was never advised of a more-preferred way since then. Use of the foot break is not enough to prevent rollback on a steep hill. What's the technique of choice these days?

 

[TomT]

I was taught the heel/toe method of brake/accelerator which works on any car with any type of transmission under any circumstances.

 

[KeithFrechette]

Interesting. I suppose that would work if you do it enough to keep the coodination accurate. Once screw-up, though, and you're up-close-and-personal with the driver behind you.

 

[davewill]

Got curious and played around on some of the hills in my neighborhood. On all but one, I couldn't even GET the LEAF to roll backwards. I would take my foot off the brake and just sit there. On the steepest one, I could get it to roll backwards, but it happened so slowly that the time it took to shift to the accelerator resulted in a very minimal rollback (an inch?). I also tried the parking brake auto-release, and it worked well. If I was stopped on a super steep grade, I would use the parking brake. You could also shift your left foot to the brake pedal if you were so inclined, but I don't really see the need.

P.S. I also use the heel-toe method when driving manual transmission cars.

 

[TomT]

Deleted.

 

[DaveEV]

It was when *I* was learning to drive (in the mid-80's), and I was never advised of a more-preferred way since then. Use of the foot break is not enough to prevent rollback on a steep hill. What's the technique of choice these days?

I've NEVER heard it recommended to feather the clutch/accelerator to hold the car on a hill when stopped. It's simply not reliable and puts a lot of stress on the transmission / clutch since it has to sit there slipping and generating a large amount of heat. Do this on a manual transmission car and you'll quickly wear out the clutch. Frankly if you were told to do this - your driving instructor had no idea what he was talking about.

If your brake pedal can NOT hold the car on a hill, you've got problems with your car. Period. The brakes on any half-way decently maintained car will easily hold a car on the steepest paved hill around until the tires start slipping. With no stress. The force required to hold a car stopped on a hill pale in comparison to what's required of them to perform an emergency stop from freeway speeds.

Now many cars are equipped with hill-assist features which simply engage either the parking brake or friction brakes automatically on hills, eliminating any roll back. Simply push the accelerator when you want to start moving (and engage the clutch if it's a manual transmission car.

You can do the same thing in the LEAF by engaging the parking brake manually. Push the accelerator and the parking brake will release for you.

 

[KeithFrechette]

Why such a harsh response? :| I was only conveying how I had been told to do it many years ago. And I didn't say the brakewouldn't hold. Rather, this was the technique given to ensure the car doesn't roll backward and hit the car behind me.

 

[planet4ever]

I'm sure the harsh response was because using the clutch to hold the car while stopped on a hill would be extremely hard on the clutch. However, I do remember, many years ago, learning that a simpler and (for some) more reliable alternative to heel-and-toe on a manual transmission car was to slip the clutch momentarily while moving your right foot from the brake to the accelerator. After all, unless you double-clutch all your shifts, and do it perfectly, there is almost always some slipping involved whenever you engage the clutch. They were designed to take a lot of that kind of beating.

But back to the LEAF, it isn't really obvious whether using the accelerator to hold an electric car would be hard on the car or require energy. Several months back I got into an argument about that very point on this board. I was claiming that force with no motion means no energy. I lost that argument, since others who know more about electric motors than I do said there would be heat loss in the motor windings.

Ray

 

[LEAFer]

I was claiming that force with no motion means no energy. I lost that argument, ...
Ray

Think of it in simpler terms How much energy does it take you (to fight gravity) while hanging (motionless) from a horizontal tree branch (with your feet off the ground) ?

( Of course, even standing up (motionless) ... you are using energy holding up your body. But the point really is, the car is countering the force of gravity on an uphill incline. )

 

[planet4ever]

I was claiming that force with no motion means no energy. I lost that argument, ...
Ray

Think of it in simpler terms How much energy does it take you (to fight gravity) while hanging (motionless) from a horizontal tree branch (with your feet off the ground) ?

( Of course, even standing up (motionless) ... you are using energy holding up your body. But the point really is, the car is countering the force of gravity on an uphill incline. )

We really shouldn't reopen this old argument, but you are wrong. Make it really simple: Hang a weight on a peg. How much energy does it take to keep it hanging there? Park a car on a hill and set the hand brake. How long will the car be able to sit there before it runs out of energy? I lost the argument not because of mechanics - a force with no displacement does not transfer mechanical energy - but because of thermodynamics.

Ray

 

[smkettner]

Don't ride the clutch, use the service brakes. You were taught wrong.

In the LEAF you should also use the service brakes or as an alternative use the parking brake that will auto release when the throttle is depressed and forward motion is desired.

 

[LEAFer]

I was claiming that force with no motion means no energy. I lost that argument, ...
Ray

Think of it in simpler terms How much energy does it take you (to fight gravity) while hanging (motionless) from a horizontal tree branch (with your feet off the ground) ?

( Of course, even standing up (motionless) ... you are using energy holding up your body. But the point really is, the car is countering the force of gravity on an uphill incline. )

We really shouldn't reopen this old argument, but you are wrong. Make it really simple: Hang a weight on a peg. How much energy does it take to keep it hanging there? Park a car on a hill and set the hand brake. How long will the car be able to sit there before it runs out of energy? I lost the argument not because of mechanics - a force with no displacement does not transfer mechanical energy - but because of thermodynamics.

Ray

ok ...

 

[ERG4ALL]

I prefer manual ICE cars. When purchasing one, I like the parking brake that is a lever between the front seats. That way, I can hold the car on a hill with my right hand and still have use of both my feet for clutch and accelerator (our PT Cruiser was this way and our Mini Cooper is as well). As far as an automatic transmission and the LEAF are concerned, I've gotten in the habit of using my left foot for the brake and the right for the accelerator. Not only does that make it easy to hold on a hill, but I believe that gives me just a split second faster braking when I get in a congested situation where I may expect the unexpected. I hold my left foot over the brake pedal until the problem area with an anticipated panic stop must be made is over. I've had no trouble moving from an automatic to a manual with altering what I use the left foot for. Usually with a manual its left foot clutch and right foot gas and brake.

 

[donald]

On my driveway, which is fairly steep, it rolls backwards quite easily and quickly when in D and with the foot off the brake or accelerator.

Got curious and played around on some of the hills in my neighborhood. On all but one, I couldn't even GET the LEAF to roll backwards.

Just out of my own curiosity (!), exactly what is the hill-start behaviour of pre-2013 Leafs?

In thread http://www.mynissanleaf.com/viewtopic.php?f=4&t=10687" onclick="window.open(this.href);return false; '2013 Leaf Specs', it says;

Additional enhancements
•Hill Start Assist which enables a driver to start the LEAF on a slope without worrying about rolling backward

So, was hill start an option before, and you get roll back on some models and not other and it's now standard equipment, or is this new option one where the parking brake doesn't need to be engaged and can all be done on the foot pedal instead (whereas before it would roll back on the foot pedal, if the parking brake wasn't used)?