Braking from Neutral for Range Maximizing, 2011 Leaf

[alozzy]

Regen doesn't work in neutral because it requires the motor to be engaged, so that it can act like a generator. The single speed reduction gear "transmission" in the LEAF is what disengages the motor from the rest of the powertrain when you put the car into neutral.

So, when you put the car in neutral, there's no longer a mechanical connection between the motor and the rest of the drivetrain. In other words, there's no rotational force to turn the rotor of the motor and therefore no power regeneration.

https://www.youtube.com/watch?v=BhOEoXf ... P9LaU2wlbA

[LeftieBiker]

Sorry, but for possibly the first time, YouTube was wrong. The motor is always mechanically connected to the reduction gear "transmission." The "gear" switching is all electronic mode changing in the motor, with no mechanical "shifting."

[alozzy]

Ok, good to know. Either way, regen won't work in neutral

[LeftieBiker]

The OP does have a point, in that because the motor is always turning, it should be possible to engage Regen without having it driving the car. Maybe it has something to do with how the motor is energized to operate at all...

[goldbrick]

Hopefully this is not too far OT but my stupid question is do the brakes actually directly engage regen? On my 2017 it seems to me the brakes are just basic hydraulic brakes. I'm always in ECO mode so the regen is working anytime I have my foot off the gas while in D or B but I never thought the brake pedal would switch modes or cause the motor controller to change its operation to regen. Based on the number of green dots on the dash I can see the regen power changing with speed, etc but I never noticed it step up when I hit the brakes while decelerating. I'm sure the controllers sense when the brakes are applied and could activate some sort of regen operation. Is that the idea of this thread? To have the motor controller switch to some sort of regen operation when the brakes are applied while in N? I've always assumed the brake pedal was just connected to the brake master cylinder and the brake light switch. Is there more to it than that?

[klutzo]

Seems to work well as we have a 2015 Leaf. Coming from manual like @hackdroot I'm very used to shifting and downshifting.

My 'drive flow' is this when coming to a downhill slope.

N
then I try to gauge the distance to a light, another car, etc. as I need to slow down.
then downshift to
D with no pedal push at all
then as I get closer to the obstacle (light or car), downshift to
B with no pedal push at all
then the final last 'mile'
Brakes.

So my theory, is that with D and B I'm actually using the Regen. Only when the brakes are applied do I actually wear the brake pads and rotors.

Am I correct here gang?

Oh also, as this is an Electric Car versus an Int. Comb. Eng. Shunting to Neutral on an automatic (or manual for that matter) is not usually very wise. In an EV, is this an issue at all?

Thanks!

[LeftieBiker]

You are correct about neutral and Regen, as long as you don't press the brake pedal hard enough to engage the brakes. There is no actual "shifting" of gears - they are always meshed, so using the "shifter" as you are doing is harmless to the car. It's all just varying the electronic pathways in the motor/generator.

[goldbrick]

klutzo, I follow the exact same methodology. I've been really impressed with how far the car will coast in N and how smoothly it handles the transition between D and N. D to B is little more abrupt but well within acceptable limits IMO. In a past life, I wrote firmware to control a brushless DC motor so I have some experience in this area and I am really impressed with how the Leaf motor controller operates. The Leaf doesn't use a DC brushless motor but the concepts should still apply and I think Nissan did a good job with this part of the car.