Regen braking can be dangerous on icy roads

[I33t]

Either adjust your driving style, or go trade your i3 on a 2016 i-Miev. They are not discontinued!

 

[Stevei3]

The car failed the milk bottle test just today on the Mass Pike when the adaptive cruise control abruptly decelerated the i3 from freeway speed without warning or control input from the driver; felt a little bit queasy afterwards.

Hi,

tip: the aggressive regen when the cruise control (both adaptive and 'normal') is switched off is fixed in the november software update. The car goes into coast/mild regen modus now.

Regards, Steven

 

[jpa2825]

Thanks for the topic. When I get my new i3, I plan to take it to a wide open parking area after the 1st snow and test out some of these techniques. Hopefully I can get the feel of the regen impact in snow & ice and make that part of my muscle memory.

 

[ASUN]

Thanks for the topic. When I get my new i3, I plan to take it to a wide open parking area after the 1st snow and test out some of these techniques. Hopefully I can get the feel of the regen impact in snow & ice and make that part of my muscle memory.

Now that's smart!

 

[jadnashuanh]

One thing that surprised me when I was in a snow-covered parking lot was that even with the winter tires, when I mashed the accelerator pedal, it barely moved...the wheels did not spin, but it limited the power available radically to keep the rear tires from spinning. Now, sometimes that's useful, and you can turn that off. The lot wasn't big enough to try much with speed and regeneration, but on the streets during bad weather, I never had an issue with stopping...starting on a hill, it did try to sidestep unless I was careful. In those situations, it can help to go to one of the Eco modes...those dampen the throttle response, making it easier to feather the pedal. It's not that the i3's pedal is too sensitive...it has a fairly large motor for its size. Same reaction you'd get with a high-torque ICE...too much of a good thing is not so great when the roads are marginal.

 

[alohart]

The Mitsubishi i-MiEV, now discontinued, allows the driver to select both the engine regenerative strength (off, moderate, or potent) as well as electric engine power (moderate or potent).

Our 2012 i-MiEV had only 2 regen levels: moderate and stronger. It was not possible to turn off regen completely so that one could coast. Our i3 has an infinite number of regen levels controlled by the accelerator pedal which I think is better.

Unlike the i3, the i-MiEV produced stronger regen when pressing the brake pedal. To avoid using the friction brakes, one had to learn to just touch the brake pedal for maximum regen. But with the i-MiEV, one had to use the friction brakes to stop unlike with the i3 which can stop using only regen.

I find the i3's separation of regen from friction braking to be a better design. The accelerator pedal controls regen entirely with no additional regen produced by pressing the brake pedal. If regen deceleration is insufficient, the brake pedal must be pressed, but the full regen power caused by lifting off the accelerator pedal completely just adds to the friction braking force, so this shouldn't cause any additional jerkiness.

Interestingly, the default comfort mode in the i3 (potent regeneration, potent engine power) is the only combination of drivetrain settings not available to the i-MiEV driver.

That's true. With maximum regen ('B' mode), the accelerator pedal response was attenuated just like in the i3 Eco Pro and Eco Pro+ modes. But maximum regen and power are both considerably less compared with the i3.

On the road, I always depower the i-MiEV engine in order to smooth acceleration forces; the neck snapping power of the i3 engine, followed immediately by the neck snapping, opposing regenerative braking force, is fully capable of upsetting my vestibular system very quickly.

I never drive our i3 in Comfort mode because I, too, find the accelerator pedal response sensitive enough to make smooth driving too difficult. Unless you need to full power of the climate control system, driving in Eco Pro mode at all times would be smoother. I don't normally use the friction brakes instead modulating regen deceleration using the accelerator pedal. This results in very smooth driving with no neck snapping acceleration/deceleration.

I would certainly utilize a moderate engine power setting when driving the i3 if this were driver selectable both to improve the comfort of myself and passengers as well as to achieve increased economy.

That's exactly what Eco Pro and Eco Pro+ do!

 

[jadnashuanh]

FWIW, I almost always use Comfort mode since my trip distances are typically short, but I have no problem being smooth with the car in that mode. It's a mindset and a little practice. WIth a high-torque motor like in the i3, if you're not smooth, whiplash is very possible! It only took me a couple of miles to master it, but I have driven all of my cars with that smoothness in mind for decades, so it was almost second nature. It's not hard, but until you get used to it, it's hard to unlearn past, bad techniques. Especially with a typical ICE and its automatic transmission, the torque converter tends to smooth out transitions. Drive a manual transmission car, or a powerful EV with a single speed transmission, and any little change can result in immediate reactions, leading to a jerky trip. FOr those not able or willing to learn this, a powerful EV is probably a lousy choice. Master it, and you'll wonder how you got along without that skill and knowledge all these years. You can teach an old dog new tricks, but it may need more incentives...for you and your passengers, it's a more pleasurable trip.

 

[Jeffj]

BTW, its possible to run EcoPro for the throttle response (muted), but still keep the climate control in "Comfort" mode. Its a setting in iDrive, under "Settings/EcoPro" I think.

 

[DocRush]

FWIW, I almost always use Comfort mode since my trip distances are typically short, but I have no problem being smooth with the car in that mode. It's a mindset and a little practice. WIth a high-torque motor like in the i3, if you're not smooth, whiplash is very possible! It only took me a couple of miles to master it, but I have driven all of my cars with that smoothness in mind for decades, so it was almost second nature. It's not hard, but until you get used to it, it's hard to unlearn past, bad techniques. Especially with a typical ICE and its automatic transmission, the torque converter tends to smooth out transitions. Drive a manual transmission car, or a powerful EV with a single speed transmission, and any little change can result in immediate reactions, leading to a jerky trip. FOr those not able or willing to learn this, a powerful EV is probably a lousy choice. Master it, and you'll wonder how you got along without that skill and knowledge all these years. You can teach an old dog new tricks, but it may need more incentives...for you and your passengers, it's a more pleasurable trip.

I do agree with Jim. When we were new on i3 "my wife and I made a deal" when she declared that comfort mode is the best. (PS: She is the main driver who traveled over 90% of our 10.000 km total mileage so far !)
In other words, at the beginning she was a bit discontended with i3 and driving with ECOpro mode was raising her visible dissatisfaction.

I remember myself saying sth like "a BMW will never choose/use the middle or right side of a highway". So I voluntarily encouraged her with this choice and we almost drove in COMFORT mode.

Maybe, the huge difference between fuel and electricity prices in Turkey might affect our decision making process since there is a correlation of nearly 6 to 1 concerning her commuting expenditures when compared our old Opel-ASTRA 1.3 diesel AT with the i3.

 

[cmj912]

That's exactly what Eco Pro and Eco Pro+ do!

I was practicing this to see. It definitely does ramp things down enough where you feel like you'd have some more control.

 

[auxnbus]

One way to mitigate aggressive rear-biased braking in slippery conditions is to left-foot brake.
The basic idea is to feather the throttle with your right foot to either coast or light regen, then apply friction brakes with your left foot.
It takes a bit of practice, but once mastered, you can actually be very strategic with weight transfer.

 

[nismowu]

This topic makes me wonder....
When completely lift the accelerator, I don't think the car using 100% regen brake only because I can hear braking from the front wheels.
Can anyone confirm if that's the case?

 

[I33t]

This topic makes me wonder....
When completely lift the accelerator, I don't think the car using 100% regen brake only because I can hear braking from the front wheels.
Can anyone confirm if that's the case?

When the battery is fully charged (or nearly fully charged), the regen is disabled but the brakes are applied instead. This gives a consistent response to the driver while protecting the battery. It would be detrimental to the battery to run regen when fully charged.

 

[alohart]

The brake discs on our i3 are a bit rusty from lack of use in our humid, salty climate. So when the brakes are applied, the grinding sound is very obvious.

I have never heard the brakes being applied during regen, but I rarely charge to 100%. I do hear the brakes being applied when driving in traffic with ACC on and when the deceleration rate with regen only would be insufficient to prevent a collision with a vehicle in front.

So I have no evidence that the brakes are applied during regen except when the SoC is near 100%.

 

[jadnashuanh]

FWIW, using the actual brakes is the last thing you want if you're trying to generate regeneration! Unlike some other vehicles, the i3's regeneration is controlled by you with how you feather the accelerator pedal. The more you actually use the brakes, the less regen you'll be generating.

 

[I33t]

The brake discs on our i3 are a bit rusty from lack of use in our humid, salty climate. So when the brakes are applied, the grinding sound is very obvious.

I have never heard the brakes being applied during regen, but I rarely charge to 100%. I do hear the brakes being applied when driving in traffic with ACC on and when the deceleration rate with regen only would be insufficient to prevent a collision with a vehicle in front.

So I have no evidence that the brakes are applied during regen except when the SoC is near 100%.

Sounds fair. We live up a hill, and 99% of the time I never touch the brakes, accelerator modulation is enough. We do charge to 100% though, so I am quite aware that the regen is turned off when fully charged. Shiny brake discs are evidence, as is the feel of the brake pedal when the car is in deceleration mode going down hill and I touch the brakes...

 

[oilerlord]

Wondering if there has been any update to the car in terms of being able to modify levels of regen - either through a menu setting or coding. I live in a winter city with snow and ice several months out of the year. Though I don't think I'd have a problem modulating the regen through normal driving, I know my wife would hate the strong regen. Further, I've been reading that regen can turn completely off if you hit a bump - which I do think could cause an unexpected if not dangerous situation on an icy road

Has this been changed in 2016 or 2017 i3 model years?

 

[jadnashuanh]

At least where I live, there has been no update to add user selectable, menu-driven regen levels. But, IMHO, it's not needed since you can control the amount infinitely between min/max with your right foot! It does take a little practice, but even if you drive a vehicle without it, once you learn it, you're unlikely to forget it when switching between cars.

I will admit that to a first-time user, it can come as a surprise if they try to drive it like a typical automatic transmission vehicle, since most modern ones do not have much of any engine braking, and intentionally go into coast mode when you let off of the accelerator pedal. Once you learn the one-pedal driving on the i3, IMHO, there's no big need for adjusting the levels remotely. I do admit that I liked it better on my 2014 which had a higher level than currently applied, but it is easier for most people to drive smoothly now.

 

[oilerlord]

Thanks for your reply.

I drive a 2014 B-Class Electric that does have regen when you lift your foot off the throttle, but it's gentle. It's very easy for me to "find" the coast position, and one-pedal drive (more or less). In other words, I get it.

By contrast, the i3's regen comes on quite strong and though I probably wouldn't have a problem with it, I know my wife will, and I'd worry she might get into a dangerous situation on an icy road. I was just wondering if there was a way of setting different levels of regen - either through menus, or by coding it through the OBD2 port using Rheingold, or another coding solution. I'm guessing you can't modify it, but the fact that the car can release the regen over bumps; it would make sense that there could be a way to program it so it's always off. Personally, I'd prefer the car to coast since I assume that the brake pedal is set to regen anyway.

 

[brorob]

At least where I live, there has been no update to add user selectable, menu-driven regen levels. But, IMHO, it's not needed since you can control the amount infinitely between min/max with your right foot! It does take a little practice, but even if you drive a vehicle without it, once you learn it, you're unlikely to forget it when switching between cars.

I will admit that to a first-time user, it can come as a surprise if they try to drive it like a typical automatic transmission vehicle, since most modern ones do not have much of any engine braking, and intentionally go into coast mode when you let off of the accelerator pedal. Once you learn the one-pedal driving on the i3, IMHO, there's no big need for adjusting the levels remotely. I do admit that I liked it better on my 2014 which had a higher level than currently applied, but it is easier for most people to drive smoothly now.

While in most situations I agree with this argument, I still believe an option to turn off or down the regen level would make the car safer and easier to drive in the winter. When you have driven an ICE vehicle for most of your life your natural reaction in a split second decision may be to take your foot completely off the accelerator pedal, which I've done a few times.

What really surprises me is that the regen will continue to "lock up" the wheels if this situation occurs. Automatically disengaging the regen when this happens would be much safer. I've tested this by taking my foot completely off the accelerator pedal when my road was icy and the rear wheels stay locked until the car stops or my foot presses the accelerator. I've tested this a few times to make sure it wasn't a one time thing.

Don't get me wrong, I normally love the aggression level of the regen but I wish I could turn it off on some of the really bad driving days. I am driving with the all season tires and this could be part of the issue, but BMW shouldn't assume that everyone can afford a winter tire setup, especially with the odd sized tires they chose.

The best advice I've read to help with this in a quick stop situation is to mash the brake pedal and let the ABS and stability control do their job. There is also the switch to neutral trick, but reaction time is needed for that.