Regen braking can be dangerous on icy roads

brorob said:

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.

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Wow. When I lift off the throttle on my B250e on ice, ABS kicks in immediately. I never considered that on the i3 that the wheels would actually lock up instead of engaging ABS.

I don't live in an icy climate, however, there is this one driveway to a local restaurant that I generally enter at an off angle. Now, when I enter the driveway quickly and there is water on it and I let off on the accelerator, I can feel the regen braking kick in, but if the rear wheels begin to slip, the regen braking immediately disengages (almost feels as though the car is accelerating because of the sudden stop of the regen braking) until the wheel is able to regain traction.

I would imagine the behavior should be the same on snow/ice. In my experience, the regen braking should shut off if wheel slip is detected...

2015 REX with all the latest software updates.

jadnashuanh said:

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.

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Not true. Since the moment you let off the accelerator to move you feet to the brake pedal, re-gen braking is already activated.

ASUN said:

jadnashuanh said:

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.

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Not true. Since the moment you let off the accelerator to move you feet to the brake pedal, re-gen braking is already activated.

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True, but by using friction brakes, you're dissipating energy that could have been recaptured via regen, so using friction brakes regenerates less energy as jadnashuanh stated.

new here, i3 for a month, first day snow and almost hit a street light.........

SIMPLY dangerous behavior (my sc430 does not do this, my 850 CSI does not do this, my outlander PHEV does not do this even my renault VAN does not do this and I never had a car doing this.... the last 20 years or so.

You drive at safe speed and distance and have to slow down faster then anticipated (car in front, animal, person, etc ....JUST happens):
- You have to lift the pedal fast to get to the brakes BUT before you can touch the brakes ReGen kicks in STRONG (you let of fast so it kicks in STRONG !) and LOCKS the rear: you become an unguide missile !

You take a roundabout at a very very very slow speed (remembering you just been launched by the car and almost hit a pole) and lift off the foot a FRACTION too fast: regen locks the rear and you loose the rear...... scary (easy to correct if you know how). The same roundabout I can do with my eyes closed in the SC430 (snow button) and way faster and nothing happens.

Don't even THINK about lfting the pedal in a corner ... even slightly, it will break out.
Downhill.... I live in a flat country....but i can imagine it being a very scary experience.

So i started using the LEFT foot to brake to avoid the ReGen..... after testing the above again on a empty parking place (wanted to find out how to control the car). Even did search the menu/manual.... "there must be a setting for this that i misssed".....nope.
I would not let my girlfriend drive it in snowy conditions, she would hit something the first corner !

COMPLETELY DANGEROUS behavior.... period. Should be exposed.... hope we get video's on youtube or top-gear "kills" it in the snow.

Who designs a car that locks the rear in Icy conditions: get a SNOW button/setting..... LIKE ANY normal car has, fix it (it is a BUG).
Would not surpise me if BMW get's claims......very easy to prove.

Regen locks rear wheels and there is no way to avoid it, snow tries or not dangerous on any icy/snowy road.


p.s. love the car but this is a huge design error. Next snowy day: no i3 for me anymore (not because I lack driving skills but don't want to wreck it).

Which tires do you have on your i3? It makes a HUGE difference. The all-seasons aren't horrible, but the 20" summer tires are. IMHO, if you drive where it is snowy, icy, or even just cold, winter tires are called for. An all-season, is a compromise all seasons, and a summer tire should never be used when it gets cold, especially if the road's covered with anything. There's a reason why enlightened places mandate winter tires...the USA's laissez-faire attitude leaves us in the dark sometimes. I've been through 3 winters with mine (winter tires all around), and not experienced a problem. At least on mine, there's a slight delay then ramp-up of the regen, giving you enough time to get on the brakes if needed before regen hits hard.

winter... (not important to prove the point)
Snow it will work (tryres will have grip on the dry snow), but as soon as the snow becomes icy it's dangerous.

Who uses the handbrake before bracking in winter..... nobody....YES the BMW i3 does.

And not just me.... lots of post on this and other forums about this behavior, most people can not drive this car safely in winter.
Quotes like: "would not let my wife drive it", "accident waiting to happen", "scary", "dangerous", "garaged it in winter" etc......

Most that do drive it in snow/icy conditions:
Use left foot braking !!!!
Put in NEUTRAL !!!!
Downhill....Neutral and braking.... long hill and your brakes will start to fade.....


It is not a car that everbody can just drive safely in these conditions.

Agree that starting out with the proper equipment helps a lot.

When I got my i3 last year in late November, I drove it around for a week on the oem all-seasons while waiting for my order for a set of winter tires (and rims) to arrive. It was a pain. When I swapped over to winter tires, it was, as Jim pointed out, a huge difference.

Of course, even with proper equipment, I still drove defensively - increased my following distance to 6 seconds, slowed down to 20% of posted limit, etc. Maybe because I because I adjusted my speed, I'm able to use regen-braking without issues.

Probably the majority of cars out there on the road today are front-wheel drive. Most trucks that are not all-wheel drive, are not. The i3 is not. The good thing is that unlike an unloaded pickup, the F/R loading on an i3 and most BMW's is close to 50:50. I was in an icy parking lot tonight and played a bit with letting off the accelerator and maximizing regen...the car did not slide at all. I could get the antilock to trigger during acceleration. ABS stomping on the brakes was active. The car always went straight. It's not as stable as my all-wheel drive GT, but it's not terrible or dangerous, at least in my view. Obviously, some feel otherwise. Don't know what circumstances make that the case. But, I do not feel it is dangerous if you're driving sanely. It's imperative, especially in the winter when the roads may be compromised, to look ahead, know what's going on around you, and anticipate so that you minimize abrupt actions. This makes it safer for those around you, too.

I might add: most of the time it is really ok......

But we had snow and above zero temps (netherlands). We have no real winters. They do not clean the roads very well, so piles of snow on roads as well.
Result snow and ice all over the place (winter tires are not even mandatory by law in our country). Normally it last a few days.
--> I did drive 20m on the epoca's and back inside and changed to winter ...... crazy tires for snow (zero grip.....would be nice to get that improved as well ....).

So you drive, car has grip no problems (you are on snow). Speed 40km/h, go of the pedal fast and the rear wheels are suddenly on an icy part and front runs into to a pile of snow, 20cm or so. Then regen locks the rear wheels on the ice part, front dives into the pile.... you loose the back.
Because front was in 10-20cm snow (not that much, but enough) is just dives in the front a bit and creates a perfect turning point for the car to break out.
If it would have been all ice.....it will go straight.
If the rears would not lock.... it would go straight (sliding over the front wheels a bit, tracking/abs kicks in and no problem).

That day I had to drive using my LEFT foot for braking. Going straight zero problems, accelerating no problems, but every corner was tricky (snow and ice).

Point is the car cannot see/detect this situation and regen locks the wheels and front dives in. Simple setting: no regen/snow would prevent this.

This way it would just go straight and if in SNOW setting it will know as soon as you let go of the pedal you are going to brake and could even react faster then you can, using the normal traction control systems. Would be wise to limit this to 50-70 km/h and adjust pedal/engine response.

My lexus does that: limit engine torque, limit speed, limit pedal response, get more pedal distance and adjust traction control, really easy to drive in snow with 245 tires and almost 300hp, lots of torque and rear wheel drive and that's 2002 technology !
Just an example... a lot of cars do this correctly.

This is 2013 and they missed something.....

Putting the car in Neutral when you need to slow down will "turn off" the regenerative braking.

Tap the brake pedal, and turn to N. It's tricky, try practicing on dry surfaces first.

This will help with not having the rear wheels lock up on slippery surfaces.

The i3 is my first RWD. And the 2 cars I had before it were both AWD. Here's one of the videos I watched to prep myself for winter driving with a RWD.

https://youtu.be/TbWBqXVxEB0

And I think it's been mentioned somewhere in this forum, switch to EcoPro in winter conditions so that throttle response is gentler and you still get heating.

I also have the traction control setting bookmarked on one of the memory buttons so I can easily turn it on or off.

prettig said:

. . . Speed 40km/h, go of the pedal fast and the rear wheels are suddenly on an icy part and front runs into to a pile of snow, 20cm or so. Then regen locks the rear wheels on the ice part, front dives into the pile.... you loose the back.
. . .
This is 2013 and they missed something.....

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I live in the USA Southeast so I've not had an opportunity to do any snow or snow/ice driving. Just I'm surprised a German company where winters are more severe would release a car that is hazardous in snow and ice.

If you get a chance, could you replicate the problem and share a video showing the problem in a safe place like a parking lot?

It would help if it included the displays so we can see all of what goes on. If using a cell phone, there are Apps that can record G forces.

And "2013" ?

Thanks,
Bob Wilson

not that easy to do ...... we just have snow for a couple off days a year.

And "this is 2013": in 2013 the car was released (i have a sportcar from 2002 that drives better in the snow with summer tires).
They missed something that has been solved by most cars (incuding bmw's) decades ago.

What I also find "strange":
Standard tires (ecopia), really bad in snow (almost no grip). Lot's off countries do not have real winters.
They should develop better tires (all-season) or tell people you NEED an extra set of winter tires with this car.

I've been following this thread from the beginning and finally registered to the forum, because I can't take it anymore.

I live in Switzerland and at the end of each working day I have to climb a small mountain (approx. 1500 feet) to get to my home.
We have snow on this road for about 4 months out of the year, I've been driving cars for 40 years, and I can assure you that the I3 is one of the safest car on Ice and snow that was ever built.

For some people there may be something wrong with the setup of the car, outdated software, or they simply bought cheap crappy winter tires that don't work.

But I find it hillarious, that somebody who has "only a couple of days snow per year" , claims that the car is unsafe and that his sportscar with summer tires is a better drive in the snow.

Sir you haven't got a clue what your are writing about -- and thinking about it a bit more, you are probably a troll!

Don't feed the troll -- go out there in the snow and enjoy your I3 - it's a pleasure to drive and it is very safe !

I'm also not understanding that an I3 is dangerous to use in winter. I'm living in Norway and I at my second winter with my I3. This car has become our families nr 1 car. Our Mercedes S204 C250 4matic is almost not in use anymore. The I3 is getting up and down every places summer and winter. The Regen function is working wonderful also at winter. My car is delivered with Blizzak winter tires.

IMHO, the average American driver is lousy compared to some places in the world that actually require people to both know the rules of the road and to exhibit skills before they can get a driver's license. The driver's tests in the USA are a joke. Throw in the attitude exhibited by way too many people that they don't have to follow the rules, and you set yourself up for dissatisfaction. Today's cars have all of these safety features in them because people do not take driving as their first priority when in the car what with the number of people you see shaving, putting on makeup, talking or texting on their phones, and just plain not paying attention. FWIW, a manual transmission vehicle in a lower gear when you let off on the gas can be quite a handful when the roads are icy, too. Millions of them out there, although fewer probably in the USA than elsewhere, but people have been driving them safely for over a century. If you're paying attention to following distances and lights and stop signs, you have plenty of space to slow down before there's a problem. Way too many people are tailgating, which gives you no time to react. How many people do you see that only wait to slow down for a red light until just before it becomes a panic stop? Good driving is a skill that takes practice, and understanding the vehicle and its capabilities. Put the right tires on it, and drive sensibly, and it's not an issue if you do. That the i3 may take a little more skill than some others, so what? Personally, after 3 winters, and going on the fourth, I've not had an issue, and NH has gotten a LOT of snow in that time - one year, over 100-inches.

For people that don't get snow often, it doesn't matter if it's an i3 or something else, those first few snowfalls of the season, and there are a lot more accidents because people are not paying attention and have to relearn (if they ever knew!) how to drive in snow. It's probably best on any car to avoid those days if you can, or wait until later, after the bulk of the traffic has left and the roads can be cleaned up a bit more. Suggestion, until you become comfortable, extend the following distance to at least twice what you would have in normal times until you relearn and sharpen your skills. Doesn't matter what car you have...if you drive it the same way in summer and winter, when winter arrives along with bad weather, you're setting yourself up for problems.

One of the software changes BMW made over the life of my 2014 vehicle was to delay and soften how the regen is applied. Long ago, they reduced the amount available (which I didn't have any problems with, even in winter). Remember, you can adjust the amount of regen with your foot, and if you have a safe following distance, you can slow down without issues.

@SwissDI3

You may find it hilarious but you do not know my driving skills .......(off roader for decades in several climates, race track experience). I know when I car does something it is not supposed to do.
Not sure who's the troll is here (childish remark anyhow, its's a forum: share and discuss do not point at people).

It is GOOD on snow, NO good in the SPECIFIC conditions I described........(very specific).
And if I were the only one, you might have a point. But lot's of people have in different parts off the world in different climates.

I did research BEFORE i did post this, just to make SURE i am not the only one (because I could not believe it happening !).

I posted/shared it, so I am done, just a matter of time a "new" owner posts his expierence and maybe BMW will start looking at it.

My apologies !
I believe there may be something wrong with your individual car.

We had lots of snow and icy roads in the past few days in CH and I purposely tried to reproduce the behaviour you mentioned.

In a 2017 REX with the latest software (and winter tires of course), it is impossible for me to lock my rear wheels during start of regen for more than a few Millisec.
The car immediately discovers that something is wrong and just disables regen automatically - I believe that's what the car should do as well in your opinion. No need to implement a snow/ice button - the car does it by default/design already.

The car never went out of control or required any special driving skills to stay safely on the road.
I would happily give my I3 to a beginner driver in these conditions - it is a very safe design in my opinion!

Once again, I apologize for my previous posting - you are absolutely right that this is a forum and everybody has a right to an opinion.

ok no problem, my car is 2013 REX but has the latest software and it went sideways for 10m on winter tyres.

I had to use left foot bracking, get the steering into the sliding direction and use to gas pedal to gain control again....... i was really surprised it did this and my "mother" would have driven into the streetlamp......
And yes very difficult to replicate, managed to do it once, problem is not snow it it snow and icy parts. As long as the tires feel grip it's really ok.
If all lose grip it is fast to correct.

But as soon as you steer in a bit and brake (regen) and the rear wheels are on ice and front in snow it will brake out.
It does detect it to late, abs does not work anymore (because it's going sideways, so not traction on the wheels).

It is really specific, but i can control most rear wheel driven cars that brakes out (if not to crazy speeds), this one i could barely.

Don't get me wrong.... i love this car ! But I agree with the people reporting it, it does something very strange.
But enough ...... it's my opinion, yours is different, no problem.