What happens when you shift into "neutral" while moving?

[CGameProgrammer]

If you're driving along and shift into neutral, does that allow you to coast without regenerative braking or is there no way to coast in this car?

 

[i3an]

Ease your foot off the throttle and find the sweet spot just shy of engaging the regenerative braking, not unlike slipping the clutch.

 

[alohart]

If you're driving along and shift into neutral, does that allow you to coast without regenerative braking or is there no way to coast in this car?

Yes, but regenerative breaking is still available when pressing the brake pedal. The better way to coast is as i3an described by adjusting the power pedal so that the power gauge is in the neutral position between regen or assist. This allows the driver to have assist or regen without shifting back to D.

 

[jadnashuanh]

SOme people make a huge deal about cars that have an paddle or a menu choice to adjust the level of regenerative braking and feel a car without that cannot be driven smoothly or to coast. Well, their totally wrong if you understand how regen is applied on the i3! You, as was said, can easily adjust from cruising to coasting to variable amounts of regen just by using your right foot. Once you get the hang of it, you won't have any need for one of those other crutches. I guess it could help during the first hour or so of buying the car, or maybe for a new driver, but really, it only took me a very short distance to get the hang of it.

You WILL run into smoothness issues if you drive it like a conventional ICE and automatic transmission...those tend to coast when you totally get off of the gas...the i3 goes into max regen. Just ease off of the go pedal, and you can do anything from coasting to braking lightly, to full regenerative braking. In fact, when I bought mine, the maximum regen was higher, and boy did people that did not understand have issues, sometimes to the point of wanting to get rid of the car. I chalk that up to never reading the owner's manual or having a good brief at the dealership. One of the s/w updates lowered the max regen and a later subsequent one tapered how it was applied rather than it being quite abrupt. That does help when on cruise control...it gives you a brief moment to get on the pedal to then do what you want without it jerking you around.

 

[CGameProgrammer]

Thanks guys. I'm glad it's possible to coast in neutral but it does sound like the one-pedal method is generally an easy way to do it. I didn't realize it would be that easy to see if you're coasting or using/generating power, or that the regen can be so easily modulated.

 

[i3an]

Jadnashuanh: yes, but since the software "upgrade" the max regen is now insufficient for some situations, and I for one would prefer a manual control or override. For example, there are some hills in San Francisco where even with the foot off the go pedal the car is accelerating downhill and the foot brake has to be ridden; and there are other not-quite-so-steep downhills where max regen will hold a steady speed but the foot brake has to be applied to come to a stop. So if my destination is on the other side of Twin Peaks, the shortest/quickest route is up and over, but going around the base, though longer, is less of a hit on my range.

 

[CGameProgrammer]

For what it's worth very little energy is regenerated when coming to a stop; it's when moving at a good speed that the most energy can be gained, with the rate decreasing exponentially as speed decreases. So you're not actually wasting anything by braking to a stop when your speed is already low.

 

[i3Alan]

For what it's worth very little energy is regenerated when coming to a stop; it's when moving at a good speed that the most energy can be gained, with the rate decreasing exponentially as speed decreases. So you're not actually wasting anything by braking to a stop when your speed is already low.

It actually takes energy from the battery to complete a stop in the i3. Once the speed is very low, the additional deceleration must come from applied energy as the regeneration below a certain speed will not generate enough energy to slow the car to a stop. My guess is that the threshold between regenerating (putting charge into the battery) and using the battery to complete the stop, when on a flat surface, no wind, light vehicle load, is probably around 3-6 MPH. Headwind, incline, or heavy load may reduce the threshold, while a tailwind or decline will increase the speed at which energy is consumed to complete a stop. Any more than a slight decline or fair tailwind, and the car will simply not stop without the brake pedal, to avoid any significant energy consumption while emulating the feel of regen all the way to zero MPH. That is, even when consuming battery charge to complete a stop, it is very slight.

 

[Joff]

So if there is no harm in coasting in neutral, what is the reason that the manual forbids towing "four wheels down"? Are they worried a person might leave it in drive, and overcharge the battery?

 

[alohart]

So if there is no harm in coasting in neutral, what is the reason that the manual forbids towing "four wheels down"? Are they worried a person might leave it in drive, and overcharge the battery?

While coasting in neutral, an i3 is in the drive readiness state. When a car is towed, it's in the off state. My guess is that the drive motor will generate power when spun in the off state as will any permanent magnet motor. In neutral in the drive readiness state, the motor controller likely counteracts that power generation. If true, the power generated by the motor while towing might damage the electronics.

That said, I don't understand why towing with the rear wheels off the ground isn't allowed. Maybe it's because with no steering wheel lock, the front wheels could turn left or right which could cause problems.

 

[jadnashuanh]

If you left the car in drive and towed it, it would be in max regen mode. If you can't put it on a flatbed, you could probably tow it with the rear wheels up and the steering wheel locked straight. Not sure how well it would self-center being pulled backwards, so strapping the wheel would seem to be a requirement. By far, the best way to move it is on a flat-bed.

Maybe the worst case scenario if being towed flat would be if the tow truck needed to back up...keep in mind that the car 'locks' it from rolling against the selected drive direction (so, if in drive, it won't roll back, and vice-versa). FWIW, it's a bit tricky to keep the car in neutral, it really wants to go into park when you shut it off.

The restrictions are much different from an all-wheel drive vehicle...you don't really want to tow one of those, either.