Regen braking can be dangerous on icy roads

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brorob

Well-known member
Joined
Oct 31, 2015
Messages
104
I'm posting this under the problems area of the forum because I think this safety concern should be addressed by BMW. Curious if others have experienced this.

Basically I had the rear end of my i3 "kick out" a few times yesterday while driving home on icy roads. This happened when slowing down for a stop sign when already driving slow. Freaked me out when this first happened but I was driving slow enough for the conditions to avoid the ditch and any vehicles. Had this happened on a multi-lane road, the rear end probably would have hit any car next to me. Fortunately this only happened a few times and I didn't hit any ditches, cars, or mailboxes.

I'm surprised that the BMW engineers didn't take this into consideration when engineering the aggressive regenerative braking system. I think it would be helpful (and safer) if there was a "snowflake button" that could be selected to either completely turn off the regenerative braking so only the brake pedal activates the brakes, or to significantly reduce the regen when taking your foot off the pedal. I would feel much safer driving the car in these conditions if this feature existed. The Volt has the option to change the regen level so I'm sure BMW could do the same.

This commute was a rare occurrence, probably the worst drive home since I've lived north of town for over 15 years. Roads were literally covered with ice and main highway (which I would have avoided) was closed. Every northbound road was backed up with cars either stopped or going 10-15 MPH. The commute that usually takes less than 30 minutes took about 2 hours. Unfortunately I can't afford a winter wheel set so I'm cautiously driving this winter on the all season tires. I did have less problems than some other vehicles driving up a few slight inclines in the icy conditions.

Anyone else experience this?

Off topic, I was able to conserve the battery by using the heated seats and keeping the cabin heater off, but I did have to turn on the defrost a few times to remove condensation from windows. I was happy that my range didn't change much after about an hour of stop and go traffic at night while using the heated seats and playing music fairly loud.
 
YOu, as the driver, have ultimate control of the amount of regen used by the position of the accelerator pedal. It is not hard to coast or adjust the amount of regenerative braking to help avoid those situations.
 
I'm surprised to hear this. As once a motorcycle rider I learned (the hard way) to lean on the rear wheel brake first in slippery conditions, so as to anchor the back end and avoid fish-tailing, and I presume the i3 does the same as the regen works only on the rear wheels. Perhaps it is time to pony up for those winter tires.
 
Hi guys,
it has't been a problem for me when driving on normal wintery roads, even in mountainous areas (Switzerland, Austria), but I've noticed two things:

1) we were caught in 10 centimeters of new snow on 2000+ meters in the Swiss Alps on summer tires in june this year. This was not funny. Uphill was still sort of possible with help of the DSC system, but downhill was downright dangerous. It seems the stability-control 'needs' winter tires in snowy conditions.

2) for me, it's impossible to drive very slow (say 10 km/h, 6 mi/h) downhill on slippery roads. Sit rep: heavy snow, ca. 15 cm new snow on the road from our rented holiday-cottage in Austria. This time on the appropriate winter tires. Steep grade (say 10%), good tarmac road surface under the snow, road barely as wide as our car, very, very tight hairpins. The car wanted to rocket downhill at the slightest feathery touch of the accelerator, or wanted to stop due to regen when lifting a bit. This made a controlled, slow, confident descent impossible. The second time we had to negotiate the road, I had to put the car in 'N' and use the brakes to gain some sort of control.

Caveat: a 'snow' setting would be welcomed by me. Or the system has to be tweaked to perform better under the circumstances like #2

Regards, Steven
 
People need to learn to feather the pedal a bit more carefully. It really isn't hard to go between accelerating, steady speed, coasting, and mild to full regen by the position of your foot - it's all about smoothness in your actions and a little finesse. This gets harder if you are switching between 'normal' cars (say an ICE) and the i3, but once you learn it, you'll have lots more control. Summer tires in the mountains with snow or ice can earn you a significant fine in much of Europe, and almost certain 100% liability should you be in an accident. Worst case, chains may be called for as well. BMWUSA choses not to import the OEM set to the states, but should be readily available in Europe. I guess I've been lucky, in my driving, I've only needed chains once to get me where I needed to go, but they probably would have been a safer choice a few other times as well.
 
jadnashuanh said:
YOu, as the driver, have ultimate control of the amount of regen used by the position of the accelerator pedal. It is not hard to coast or adjust the amount of regenerative braking to help avoid those situations.
If one is trying to coast to a stop but one's deceleration is insufficient, the additional regen when either lifting the accelerator pedal more or actually braking could cause a loss of rear wheel traction.

Years ago, I drove a school bus in Vail, Colorado. The bus had snow tires but no studs. Once, when the bus was empty, I was coasting in gear on a very icy downhill freeway offramp. Engine braking caused the rear wheels to lose traction. The only way I was able to regain control was to shift to neutral to eliminate the braking force from the rear wheels and then pump the brakes lightly to decelerate (no ABS back then).

So if I were driving an i3 on icy roads and lost rear wheel traction while decelerating, I'd do as Stevei3 did: shift to neutral to eliminate all regen braking and then use the brakes to decelerate (ABS should help).
 
I've been driving BMW EV's since 2009 and have gone through six winters with them. The MINI-E in 2009-2011, the ActiveE 1012 to 2014 and the i3 from 2014 to now and have probably driven more than 20,000 miles in the snow and ice so I've had a bit of experience with this.

My take has been that the regenerative braking has actually made the cars perform better in icy conditions. By controlling the level of region, and mixing it in with a little friction braking, you can really keep the car in better control than with friction brakes alone. jadnashuanh said it correct about the driver being able to control the amount of region applied. If your going fast enough were you need to pull off the accelerator completely and abruptly, than you may be going too fast for ice covered roads in the first place. Now, emergencies to come up, and you need to stop quickly, but in my experience the traction control and ABS on the i3 seems to work pretty well with the regenerative brakes in preventing too much slippage.

The i3 does perform better in these situations than its predecessors and it seems BMW is getting it better and better as they have more experience with EVs and regenerative braking. One thing to note is that I do have dedicated winter tires. My i3 has the 20" sport wheels with the Summer-only tires so I really had no choice. I always recommend winter tires for any car that is exposed to snow, ice and a couple months a year of temperatures under 40 degrees. Winter tires make a huge difference. Even the best "All Season" (no season, really) can't compare with how much better winter tires perform in cold weather driving.
 
Hi guys, Jim, Tom,

sorry to be on the defensive side here. I may not be an expert like Tom in winter E-driving, but I do have some experience in these circumstances (for a flatlander), also because I used to be an avid offroader, accustomed to deep mud (with ice underneath) and snowy conditions (picture Finland in winter).

I try to state two points, on the first we agree:

a bit of a moot point (duh!): winter tires are a must. Jim, you are correct that in Germany and Austria, winter tires with good thread are compulsory. Mind the thread: anything with less than 4mm is considered a summer tire in Austria! The fines for inappropriate rubber are *really* hefty (I think up to 50.000 euros), liability woes aside. When we were caught out in the snow (point 1), it was a freak snowdrift in june that surprised even the Swiss... It made for an interesting experience: the Ecopia summer tires, unlike Tom's 19 inchers in our case, perform terribly on snowy slopes. No brainer point made....

Over to the second point:

I agree with you that under normal winter driving conditions, the cars set-up is very good. It is easy to feather the E-throttle and control regen to drive very very 'softly', thereby never loosing traction. Also, DSC works perfectly here. But the case I made is that there has been a situation where I wanted to go so slow that normal driving parameters no longer seemed to count. The problem for me was not caused by loss of traction per se, but by the inability to maintain a slow, steady pace to the next hairpin. Upon lifting but a hair of the throttle, the back wheels wanted to lock-up. The descent was fairly long, so I had ample time to try to find the sweet spot of the throttle, but I wasn't able to find it. In our 4x4, we would have used the diesels engine braking in low-range first or second gear to keep the speed in the neighbourhood of a brisk walking pace. Granted, this was a situation where our 4x4 would have been better suited, but has anyone tried this with their i3? Recap: 3 km (2 mi) downhill, new snow, ~10% incline, hairpins barely wide enough even for i3's turning circle, winter tires.

BTW: switching to neutral on one occasion was a violation against my offroad lesson #1: never ever drive but one foot not in gear. I've seen interesting and potentially devastating accidents happen, for instance when one of our groups pickup popped out of gear on a 200 meter descent of ~25% in the Belgian forests...

Regards, Steven
 
jadnashuanh said:
YOu, as the driver, have ultimate control of the amount of regen used by the position of the accelerator pedal. It is not hard to coast or adjust the amount of regenerative braking to help avoid those situations.
While I agree with your comment (and others about not abruptly taking your foot off the accelerator), there are situations when this will be hard to avoid. When I had this happen I was coming to a stop sign at the bottom of a small icy hill. This was also my first time ever driving this car in snowy/icy conditions so my brain's natural response in this situation was to take my foot off the accelerator. I was caught off guard because of how fast this happened and I'm sure this will happen to others that either haven't driven the car in the snow/ice, need to come to a stop quickly, or don't have time to react quickly enough to find the sweet spot of the accelerator. I was able to prevent this for the rest of the icy drive being conscious of regen driving techniques, luckily no icy downhills.

My point with this thread is to point out that having the ability to turn off the regen braking would make some driving situations safer. And yes, driving without winter tires in the winter isn't ideal but not everyone can budget $1800 for an extra set of wheels for a leased vehicle.
 
brorob said:
jadnashuanh said:
YOu, as the driver, have ultimate control of the amount of regen used by the position of the accelerator pedal. It is not hard to coast or adjust the amount of regenerative braking to help avoid those situations.
While I agree with your comment (and others about not abruptly taking your foot off the accelerator), there are situations when this will be hard to avoid. When I had this happen I was coming to a stop sign at the bottom of a small icy hill. This was also my first time ever driving this car in snowy/icy conditions so my brain's natural response in this situation was to take my foot off the accelerator. I was caught off guard because of how fast this happened and I'm sure this will happen to others that either haven't driven the car in the snow/ice, need to come to a stop quickly, or don't have time to react quickly enough to find the sweet spot of the accelerator. I was able to prevent this for the rest of the icy drive being conscious of regen driving techniques, luckily no icy downhills.

My point with this thread is to point out that having the ability to turn off the regen braking would make some driving situations safer. And yes, driving without winter tires in the winter isn't ideal but not everyone can budget $1800 for an extra set of wheels for a leased vehicle.

Personally I'd like the ability to turn off regen also, and I've discussed this with various BMW engineers, program managers, etc. The main answer I've gotten as to why they won't offer that (and no EV maker so far that I know of has offered that option) is that they are concerned the driver will forget they turned it off and end up in an accident because they were expecting it to slow them down. After driving a car with aggressive region for a while you really expect it to be there and could possibly forget you turned it off. I understand their concern, but I still would like to have the option for certain circumstances. For me it would be in long, highway speed trips when I'd prefer freewheel coasting, but also for others like Steven who have specific circumstances when they'd prefer it turned off too. I'm not optimistic that we'll get that option though, unfortunately.
 
TomMoloughney said:
Personally I'd like the ability to turn off regen also, and I've discussed this with various BMW engineers, program managers, etc. The main answer I've gotten as to why they won't offer that (and no EV maker so far that I know of has offered that option) is that they are concerned the driver will forget they turned it off and end up in an accident because they were expecting it to slow them down. After driving a car with aggressive region for a while you really expect it to be there and could possibly forget you turned it off. I understand their concern, but I still would like to have the option for certain circumstances. For me it would be in long, highway speed trips when I'd prefer freewheel coasting, but also for others like Steven who have specific circumstances when they'd prefer it turned off too. I'm not optimistic that we'll get that option though, unfortunately.

I can see their point where this could be a double edged sword. If it was always on by default and needed to be turned off manually at the beginning of or during a drive, may help the situation they're trying to avoid.

I test drove a Volt and didn't notice the regen breaking at all. The unknowledgable dealer told me the car indeed had it, I knew it did, but had no idea what I was talking about when I explained that I wanted the one pedal driving experience. I later learned from a coworker and Volt driver that the car needs to be driven in "low gear" to achieve one pedal driving. So if the Chevy engineers figured out a solution for this, I would expect the Germans can too.
 
FWIW, when I get into my ICE after mainly driving my i3, the first few stops can be a little scary when the car does not slow down!

The reaction of the regen is not that different from driving a manual transmission car. You can get into the same situation from engine braking. I think you have more options and probably more control in the i3 as to how to respond. Now, the number of drivers that are currently using a manual transmission is dwindling to very small numbers, and the skills associated with it are dropping, too.

I lived in Germany for awhile, and it is my observation that they take driving as a task that should have 100% of your concentration, and they tend to be better drivers in both their overall skill level and their knowledge (and adherence!) to the rules of the road. The average American driver is often distracted, rarely follows or even knows most of the rules of the road, and couldn't handle some of the higher speeds commonly seen in Germany. Certainly, there are exceptions. Understanding the car and its capabilities is crucial. Given how few ever even read their user's manual, it is not all that surprising.
 
I agree with your points about manual gearboxes vs automatics, manuals are all I drive apart from the i3. Many countries are almost totally auto gearbox, but you may not realise that some others are the other way around. UK has a high percentage of manuals, and when you hire a vehicle there, it is always manual unless you pay a premium for an auto!

However, none of my manuals have ever had the deceleration to (or near) stop as the i3. The only cars I have driven with strong decel have been race cars with high compression engines.
 
I33t said:
However, none of my manuals have ever had the deceleration to (or near) stop as the i3. The only cars I have driven with strong decel have been race cars with high compression engines.
Depends on the gear you are in, but yes, in top gear, there isn't a huge engine compression braking effect. Still, the effect is similar compared to an automatic that typically goes into coast mode when you let off with very little engine braking. Now, there are exceptions, but not universal. SOme automatics are just smarter than others!

And, as has been said, you, as the driver, have ultimate control over how much regen there is from coasting to maximum on the i3. It is something you have to practice for best effect, but that's true with lots of driving skills - takes a little time.

Something that is likely obvious to all, though, is that when the roads are nasty...one should be taking more caution, and that often means slower speeds and longer following distances. Any effect would be lessened at those more controllable speeds.
 
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).

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.

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 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.
 
sheinr4143 said:
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).

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.

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 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.

Funny you say the i-Miev is discontinued. It's not, 2016 models are on their website: http://www.mitsubishicars.com/imiev
Import into some countries may have stopped (like here in Australia) but that is different than discontinuing a production model. The sales price in Australia was astronomical which killed sales, and eventually they sold the remaining stock and demos off cheap. Can I say 'stupid' ? :)

The i3 does have good acceleration, but it's not neck snapping and the decel might be more than the i-Miev, but it isn't as strong as the acceleration and it isn't neck snapping either.
 
People, there is NO good reason to have the i3 be jerky either in acceleration or regeneration induced slowing! YOU have full control. Only if you try to drive it like a typical ICE will you have issues. Feather the pedal...it works wonders. Learn something new, it IS a new car. It wouldn't be the same or as efficient if it operated like an ICE. You can easily go from full acceleration, to cruising, to coasting to mild-strong regenerative braking simply by how you use the accelerator pedal.

When I took driver's ed, LONG time ago, the instructor placed a glass (empty) milk bottle on the floorboard of the car. If you knocked it over, you lost 5-points for the day. Do that enough, you failed. You could accelerate, brake and turn reasonably, but you had to be SMOOTH while doing it. Those lessons carried through. It's sort of like flying a plane...you do NOT want to make rapid, jerky movements unless you're in a fighter jet, trying to stay alive. You, your passengers, and your car will thank you with longer tire, shocks, and brake life. You don't have to be slow, but smooth is the key. The i3 WILL let you be smooth without a lot of effort if you let it.
 
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. Kind of like when a commercial aircraft begins to descend if you have ever experienced that sensation.

I also fail the milk bottle test in the i3 whenever forced by sudden traffic changes in the lane ahead to lift off the accelerator pedal in order to cover the brake pedal. Abrupt changes in driver input are often required by real world conditions.

I have never experienced symptoms of motion sickness when driving the i-MiEV, a much, much simpler machine which is not even equipped with cruise control and which exerts a weaker regenerative braking force than the i3 on throttle lift-off; for whatever reason, these differences allow me to drive and ride in the i-MiEV without feeling like I have just been jostled around.
 
Maybe the i3 is not the best car for you! One common reason for abrupt requirements when driving is not leaving enough space in front of you. A good practice is a 2-second gap. Yes, I know if you do this, you'll get people cutting in front of you and filling it, but that is the prudent minimum. Having that gap would allow you to be smoother, rather than having to abruptly adjust. Once you learn to feather the throttle properly, you will not have this issue AND you'll maximize your range and passenger (and yours, too) comfort. Yes, I know this is different, but it IS a different car.

The iMev has all of about 39 pounds/Hp to carry around, the i3 15.5. Guess which one will be MUCH more responsive. Sort of like driving a moped verses a sport bike. Yes, they are both transportation, but they drive very differently. The size of the motor also will determine how much regen it can produce...bigger motor turns into a bigger generator, and also determines how much energy it can recoup making it more efficient. It doesn't have to, depending on how you drive it. While smaller in dimensions, the iMev weighs nearly the same as the larger, more powerful i3. They are not apples to apples in comparison. Expecting them to be is not realistic.
 
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