Things you can do, but shouldn't

I like experimenting. For instance, just screwing around I found a bug in an Chevy HHR rental car drive-by-wire code that would allow me to have the pedal floored and the engine at idle. Some great coding skills GM has there. Grant it, not too many people would bounce it off the rev limiter and floor it at exactly the right moment after it hit, but the bug was there none the less, and very repeatable....even when driving. Imagine having your foot to the floor and the car not going anywhere.

In any case, I haven't found any real bugs in the LEAF per say. This is just some stuff I learned that people wouldn't normally do...but curiosity got the better of me.

It is possible to "neutral drop" the LEAF. No it doesn't smoke the tires, but it definitely takes off faster than just mashing the throttle. Works in reverse too.

If you put it in reverse while moving forward (I was doing 10-15mph at the time), it just beeps at you. I haven't tried park yet, nor do I want to. Putting it in reverse was an accident, I was trying for eco and zigged when I should have zagged.

If you apply the parking brake while moving, it does apply, and it also beeps at you continuously. I haven't confirmed, but I believe it applies it slower than it would when stopped.

You can power brake the car. I was a little surprised at this one as it would be trivial for the car to not apply power if you are on the brake. But you can pretty much apply full power while also on the brake. When I was doing testing, I didn't want to regen at all and with a little two foot driving and watching the power meter, you can keep the ball on the zero.

While at speed, the car EASILY stops even with full motor power applied. No runaway cars here.

That's all I got for now.

turbo2ltr said:

You can power brake the car. I was a little surprised at this one as it would be trivial for the car to not apply power if you are on the brake. But you can pretty much apply full power while also on the brake.

Click to expand...

I have been looking for a straight answer on this since October... thank you.

A related question is on the creep. Is power getting applied when stopped and the brake is held?
I think I would prefer less or no creep... so if you program something maybe that can be adjusted?

The way creep is handled is interesting. It's something I've set up on other vehicles but we didn't have as much telemetry available to us.

The leaf applies a certain amount of creep torque. What is interesting is once you are stopped for a few seconds, torque goes to zero. I assume they do this as a way to save energy. Since brake pressure is available as a reading, as soon as the brake pressure starts to get reduced, the motor torque is reapplied and you now have creep torque.

For the most part this torque application is impressively transparent. But once in a while you will feel it. You'll feel the car jump ever so slightly when you slightly let up on the brake.

The Prius does something similar with the creep torque at a stop. If you don't press the brake pedal hard enough when stopped you can see on the MFD that some juice is going to the motor-generators...

Interesting that you can 2-foot it - I would have thought at they would have implemented a throttle override with all the hoop-la over the "runaway Toyotas" last year.

I probably shouldn't even suggest it, but since the LEAF doesn't have multiple gears, it is possible that it will go just as fast in Reverse as it will in Drive. Just depends on whether the Nissan designers locked that behavior out somehow. I need to find a good, deserted road to try it out...

Karl

smkettner said:

A related question is on the creep. Is power getting applied when stopped and the brake is held?
I think I would prefer less or no creep... so if you program something maybe that can be adjusted?

Click to expand...

no...at least the power meter does not indicate so. one thing i do like about the power meter, the "needle" disappears. in creep mode there is a sliver showing but that brings me to what i dont like about the power meter.

the delay. when moving the meter seems to react relatively quick. but when taking off from a standing start, there is a pretty long delay before you see anything.

kolmstead said:

I probably shouldn't even suggest it, but since the LEAF doesn't have multiple gears, it is possible that it will go just as fast in Reverse as it will in Drive. Just depends on whether the Nissan designers locked that behavior out somehow. I need to find a good, deserted road to try it out...

Karl

Click to expand...

ahh, had a chance to test that with the ice we had the other day... oh well, its still cold out but the roads are pretty much cleared. i actually think it should since the change in "gear" is actually a change in polarity not a change in motor so sure, why not?

but the other thing is usually reverse does not have the option to disable traction control like forward does so that would go a long way towards limiting power

DaveinOlyWA said:

ahh, had a chance to test that with the ice we had the other day... oh well, its still cold out but the roads are pretty much cleared. i actually think it should since the change in "gear" is actually a change in polarity not a change in motor so sure, why not?

Click to expand...

Not even a change in polarity, they just change the timing of the three AC waveforms they feed the motor. Would the differential gears have any troubles going backwards?

turbo2ltr said:

You can power brake the car. I was a little surprised at this one as it would be trivial for the car to not apply power if you are on the brake. But you can pretty much apply full power while also on the brake.

Click to expand...

Cool! I can left-foot brake when I try the car at an autocross, then. One of the major gripes of owners who track their modern water-cooled model Porsches is that they cannot utilize left-foot braking as a cornering technique, as any brake application cuts the e-throttle control completely. This was never a problem with the older air-cooled Porsches that still used a mechanical throttle linkage. It used to be true that every car Porsche built was a race car that could be used on the street, but no more. Now they build Cayennes for soccer moms. :evil:

TT

As for hitting park at speed, I did try that. It just beeps at you as well. Just like in my Prius.

When I'm stopping a car, just before the velocity goes to zero, I release most or all of the brake pressure. It makes the stop a lot smoother. I've managed to do this easily with every car I've ever driven, including hundreds of different rental cars over the years. However, I've noticed it's very difficult to pull this technique off with the LEAF. The LEAF tends to want to continue pulling forward as you get close to stopping. I believe it may have to do with the high torque in "creep". Or it could possibly be that the transition from regen braking to friction braking is too abrupt. Would regen braking be working <5 MPH? I'm going to do a test today, throwing the LEAF in neutral at 10mph or so, and coming to a stop, to see if it reacts any different.

ENIAC said:

When I'm stopping a car, just before the velocity goes to zero, I release most or all of the brake pressure. It makes the stop a lot smoother. I've managed to do this easily with every car I've ever driven, including hundreds of different rental cars over the years. However, I've noticed it's very difficult to pull this technique off with the LEAF. The LEAF tends to want to continue pulling forward as you get close to stopping. I believe it may have to do with the high torque in "creep". Or it could possibly be that the transition from regen braking to friction braking is too abrupt. Would regen braking be working <5 MPH? I'm going to do a test today, throwing the LEAF in neutral at 10mph or so, and coming to a stop, to see if it reacts any different.

Click to expand...

What you are feeling is pulling back regen as speed drops. I've noticed this too, only I've noticed sometimes you expect to slow sooner than you do, because regen is reduced as you approach zero you have to hit the brake harder to maintain the same deceleration. We've had this "problem" on our hybrid vehicles. You want to get as much regen as possible, but you can't regen to zero speed or the driver experience suffers.

I think you'll find in neutral the car will behave much like you are used to. You can also watch the power meter (the on on the NAV screen) when you are slowing down and you'll see regen go to zero just before the car reaches zero speed..

DaveinOlyWA said:

one thing i do like about the power meter, the "needle" disappears. in creep mode there is a sliver showing but that brings me to what i dont like about the power meter.

the delay. when moving the meter seems to react relatively quick. but when taking off from a standing start, there is a pretty long delay before you see anything.

Click to expand...

I think that is because from a standing start, you are not using much power. W = F * d, so P = F * v. At low velocity, the power output is low (even though the torque may be high).

Cheers, Wayne

In electric motors, power consumed directly relates to torque output. If you are putting out 100% tq at zero RPM, you are also consuming the full output power regardless of the fact that you are not doing any "work" due to the zero speed.

Dave is right, there's a delay.

turbo2ltr said:

In electric motors, power consumed directly relates to torque output. If you are putting out 100% tq at zero RPM, you are also consuming the full output power regardless of the fact that you are not doing any "work" due to the zero speed.

Click to expand...

OK. But I still expect the power consumption at low speeds to be less that at high speeds. And the LEAF limits the power at 0 mph to avoid tire slip, doesn't it?

Thanks, Wayne

turbo2ltr said:

In electric motors, power consumed directly relates to torque output. If you are putting out 100% tq at zero RPM, you are also consuming the full output power regardless of the fact that you are not doing any "work" due to the zero speed.

Click to expand...

You are using the full output power but you are not moving, the work you are doing turns into heat instantly in the motor windings and can do real damage if the system is not designed properly. That motor will puke its guts out trying to get you moving

As a good example, look at the labeled starting (Locked Rotor) current and running current for any air conditioner compressor. It is much higher when the motor is not turning or turning slowly.

wwhitney said:

turbo2ltr said:

In electric motors, power consumed directly relates to torque output. If you are putting out 100% tq at zero RPM, you are also consuming the full output power regardless of the fact that you are not doing any "work" due to the zero speed.

Click to expand...

OK. But I still expect the power consumption at low speeds to be less that at high speeds. And the LEAF limits the power at 0 mph to avoid tire slip, doesn't it?

Thanks, Wayne

Click to expand...

turbo2ltr said:

You can power brake the car. I was a little surprised at this one as it would be trivial for the car to not apply power if you are on the brake. But you can pretty much apply full power while also on the brake. When I was doing testing, I didn't want to regen at all and with a little two foot driving and watching the power meter, you can keep the ball on the zero.

Click to expand...

This may be an alternative for starting on hills. The manual (p. 5-15) says:

Hill start:
1. Apply the parking brake.
2. Securely fasten the driver’s seat belt.
3. Check that the select lever is in the D (Drive)
position or ECO position.
4. Gradually depress the accelerator pedal.
5. The parking brake automatically releases.

Click to expand...

But I'm a bit skeptical that hoping the parking brake automatically releases at the right time is the best approach here. It would seem to me the left foot on the brake gives you more control. I haven't tried starting on a really steep hill yet but the power braking would seem to me a better approach ...

That's pretty scary, that you might be able to dump 80 kW into the motor windings with the car power braked. I hope the motor cooling system is really robust! Before many folks try this, remember that Nissan is going to have full access to whatever the car has recorded about your driving habits. And, as a backup, Nissan can always search MyNissanLeaf and read the postings to see who has been naughty. Wonder what replacing the drive motor will cost...

Is the anti-freeze solution in the car's heater common with the motor/inverter coolant? If so, we've just solved the problem of slow heatup for folks in cold climates. A second or two of power braking will have that coolant plenty hot.

-Karl

kolmstead said:

Is the anti-freeze solution in the car's heater common with the motor/inverter coolant? If so, we've just solved the problem of slow heatup for folks in cold climates. A second or two of power braking will have that coolant plenty hot.

Click to expand...

All signs point to "No" - much to my puzzlement. Figure even if the motor is 90% efficient, that's still a kW or two of heat in many situations that you could be putting into the cabin.

Also you're probably not being that serious but what you have suggested is a terrible, terrible idea
=Smidge=