regen braking and icy roads

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Learning to drive in snow/ice country on a manual transmission, we were taught to *not* use downshifting (aka engine braking, a very crude way to slow down that feels and acts kind of like high regen) in snowy conditions, and instead to stay in a higher gear and 'pump' (rapidy apply/release) the brakes to prevent/limit wheel slippage. So to me, the modern equivalent of that is to *not* use regen (the kind where you set it to Level 3 and slow down by taking your foot off the accelerator) in snowy conditions, and instead use the brake pedal, hard, and let ABS 'pump' the brakes for you. And yes, I know that the brake pedal uses regen too, but there's something going on that quickly switches the system to friction braking (thus allowing ABS) when the sensors detect the wheels locking up.
 
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subnivean said:
Learning to drive in snow/ice country on a manual transmission, we were taught to *not* use downshifting (aka engine braking, a very crude way to slow down that feels and acts kind of like high regen) in snowy conditions, and instead to stay in a higher gear and 'pump' (rapidy apply/release) the brakes to prevent/limit wheel slippage. So to me, the modern equivalent of that is to *not* use regen (the kind where you set it to Level 3 and slow down by taking your foot off the accelerator) in snowy conditions, and instead use the brake pedal, hard, and let ABS 'pump' the brakes for you. And yes, I know that the brake pedal uses regen too, but there's something going on that quickly switches the system to friction braking (thus allowing ABS) when the sensors detect the wheels locking up.
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On my old ice cars I used to use the emergency brake when going downs a steep hill. Some with foot peddle type or better still the lever type on the console. It slowed the car down greatly and it allowed me to steer the car. Of course it all depends how fast you drive in certain conditions. I would like to see how the use of the parking brake toggle would work on the Kona
 
Had a very unpleasant surprise that may be related to regen braking few days ago in "salty slush over uneven ice"-type conditions. After braking with the foot pedal I started (or tried to) to turn right to an intersection using light regen (level 1) braking. Not using the hand paddle and in this phase not pressing the brake pedal any more. Front wheels started slipping and my instinctive reaction (as learned when driving ICE cars with manual transmission) was to not touch the pedals and turn the steering wheel a bit towards the center to regain grip (actually with ICE I most probably would have been pressing the cluth pedal, ready to start accelerating again soon). Well, grip didn't come back and in the next second the car went straight into a ditch:

KonaInTheDitch_Front_Small.webp

Fortunately the snow in the ditch was so soft that the car didn't suffer any damage. And it stopped about 1 meter before a lighting pole. The car, however had to be towed out of the ditch.

Later on the same day on the way back almost the same happened again. Same type of weather and intersection and despite taking the turn extra-cautiously due to the earlier incident, for a while the car just didn't turn. Fortunately this time grip got back just in time to avoid another embarrasment. After this I set the regen level to 0 and it will definitely stay there until there's no more ice/slush on the road or I learn to react correctly. Maybe pressing the accelerator slightly might have helped to avoid/reduce slipping. Or pressing the brake pedal would have activated ABS. Actually without this second incident I would not be writing this post and think that the first incident was caused just by my lack of driving skills. But twice...

Speed in these incidents were something like 30 to 40 km/h (20 to 25 mph), which I thought to be safe. Tyres were Nokian R3 studless, driven about 8000 km (5000 miles). I have over 20 years (or winters, lasting almost half a year here in Finland) experience driving also in this kind of conditions so I thought I can handle them, but with this car while using regen this wasn't apparently the case... A little bit of understeer is quite common in these conditions and nothing to worry about normally.

My impression was that once you lose grip (in this case lateral at first), it's very hard to get it back, at least if there's slush over ice (probably causing "slushplaning", at least if/when wheels stop spinning). Could this be related to the implementation of the regen? Maybe it tries to keep a constant decelerating force applied to front wheels and due to faster reaction times compared to ICE (less rotating mass vs. ICE etc.), it may just lock the wheels in an instant?

I tried to recreate this later on a safer environment (quiet country road) but grip was too strong. Wasn't able to initiate slipping the wheels safely (so that locking would not lead into another ditch) even with the strongest regen level. Will definitely try this again if/when conditions allow a safe test.

More pictures here:
https://drive.google.com/drive/folders/10pWHegg1aINtuJ4GKheJAKOr9FFRIdn4

Also took a picture of the front (left) brake disk. Quite rusty, but most probably not related to anything here. Have been wondering how to force friction braking to keep brake disks polished. Tried hobbit's tip (switch to neutral while driving) and it works, will definitely take it into regular use. Thanks.
 
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My impression is that regen is technically a "constant torque" (or current) mode, as far as motor control goes. But, by relying on regen to slow you are clearly only exploiting front wheel traction and I'm unaware if traction control modulates that if front wheel speed differs from rear wheel speed. Using the brake pedal is going to be equally problematic because of its goal of preferring regen over friction.
You would think that when using the brake pedal, the moment front wheel lockup is detected regen would be abandoned in favor of conventional four-wheel disk braking with ABS.
 
We all need to get used to the idea of one pedal driving and remember that in order to "coast" we need to apply a light touch to the accelerator, rather than let it come all the way up. That being said, the tires that come with the car are awful in slippery conditions. I'm going to keep them this winter but plan on replacing them with the best all-season tires I can find before next winter.
 
We all "need" to do nothing of the kind, when we have configurable options.
The priority should be understanding how the systems work, and adapting
them appropriately as conditions warrant.

_H*
 
hobbit said:
...adapting them appropriately as conditions warrant._H*
Click to expand...

I always drive with maximum regen because I want maximum range and efficiency and minimal use of the left paddle. But I generally agree that if you take the time to consider conditions it makes sense to adjust regen to the conditions. However, we often don't take that extra time and its very easy to find ourselves in the same position NUPO was in; the car drifting and unstearable because of regen + slippery road. Either a slight depression of the accelerator to eliminate regen braking or a hard press of the foot brake to engage abs would have allowed for steering and kept the car on the road.
 
What the car needs is a winter mode that allows normal use of the four-wheel disk brakes. The default mode of front wheel-only braking seems problematic.
 
Hard to say how regen currently works when the front wheels start to slip, but maybe some kind of limiter could work? Like limiting the minimum rotation speed of front wheels to 95% of rear wheels. Limiting the deceleration of the front wheels to whatever the current regen level is supposed to do could also make it easier for ICE-trained brains.
 
Noting that the red line on the Hyundai graphic above is an example of a heavy braking event that partly exceeds regen capacity. In low traction conditions you would be just above the horizontal axis, entirely within the "regenerative brake" region up to a near standstill, which means braking is acting only on the front wheels. Note also the last line in the text indicates ABS/ESP is functional.
The only way out I can see would be to practice with braking in a hazard-free parking lot. Regen level should be at 0 or 1 such that it doesn't break traction simply when you lift off. But any regen level set will not subsequently affect foot braking balance as best as I can determine.
 
Nupo said:
Had a very unpleasant surprise that may be related to regen braking few days ago in "salty slush over uneven ice"-type conditions. After braking with the foot pedal I started (or tried to) to turn right to an intersection using light regen (level 1) braking. Not using the hand paddle and in this phase not pressing the brake pedal any more. Front wheels started slipping and my instinctive reaction (as learned when driving ICE cars with manual transmission) was to not touch the pedals and turn the steering wheel a bit towards the center to regain grip (actually with ICE I most probably would have been pressing the cluth pedal, ready to start accelerating again soon). Well, grip didn't come back and in the next second the car went straight into a ditch:

View attachment 7032

Fortunately the snow in the ditch was so soft that the car didn't suffer any damage. And it stopped about 1 meter before a lighting pole. The car, however had to be towed out of the ditch.

Later on the same day on the way back almost the same happened again. Same type of weather and intersection and despite taking the turn extra-cautiously due to the earlier incident, for a while the car just didn't turn. Fortunately this time grip got back just in time to avoid another embarrasment. After this I set the regen level to 0 and it will definitely stay there until there's no more ice/slush on the road or I learn to react correctly. Maybe pressing the accelerator slightly might have helped to avoid/reduce slipping. Or pressing the brake pedal would have activated ABS. Actually without this second incident I would not be writing this post and think that the first incident was caused just by my lack of driving skills. But twice...

Speed in these incidents were something like 30 to 40 km/h (20 to 25 mph), which I thought to be safe. Tyres were Nokian R3 studless, driven about 8000 km (5000 miles). I have over 20 years (or winters, lasting almost half a year here in Finland) experience driving also in this kind of conditions so I thought I can handle them, but with this car while using regen this wasn't apparently the case... A little bit of understeer is quite common in these conditions and nothing to worry about normally.

My impression was that once you lose grip (in this case lateral at first), it's very hard to get it back, at least if there's slush over ice (probably causing "slushplaning", at least if/when wheels stop spinning). Could this be related to the implementation of the regen? Maybe it tries to keep a constant decelerating force applied to front wheels and due to faster reaction times compared to ICE (less rotating mass vs. ICE etc.), it may just lock the wheels in an instant?

I tried to recreate this later on a safer environment (quiet country road) but grip was too strong. Wasn't able to initiate slipping the wheels safely (so that locking would not lead into another ditch) even with the strongest regen level. Will definitely try this again if/when conditions allow a safe test.

More pictures here:
https://drive.google.com/drive/folders/10pWHegg1aINtuJ4GKheJAKOr9FFRIdn4

Also took a picture of the front (left) brake disk. Quite rusty, but most probably not related to anything here. Have been wondering how to force friction braking to keep brake disks polished. Tried hobbit's tip (switch to neutral while driving) and it works, will definitely take it into regular use. Thanks.
Click to expand...

Glad to hear you avoided injury in both instances. I hope your Kona was also spared under body (battery tray) and or suspension damage.

In my view if you had maintained the friction braking you may have maintained some degree of control over your trajectory. Without stopping the slide the steering input is going to be futile with several thousand pounds of momentum pushing the car to move in a straight line.

As one poster surmised I think the regen must be switched out during ABS events. Otherwise if we look at regen as a form of braking then the ABS would be switching from regen to friction and with little time to allow the wheel to regain its spin regen would most likely impede the effect of ABS.

With 4 independant motors some interesting things could be done in a spin. Thinking like the Rivian tank turn.
 
There is actually a small warning in the Cdn. manual (page 5-118) in the winter driving section which is kind of contradictory "...During deceleration , use the paddle shifter (left side lever) to increase regenerative braking, but avoid adjusting it to level 3 (steering may be difficult). Sudden brake application on snowy or icy roads may cause the vehicle to skid."
I guess they assume you are driving in level 0 or 1? :confused:
May see some snow one of these days , I will have to try out the different levels and traction loss results when sharp turning (of course in a safe place)
 
Can confirm from driving in wet snow that regen 3 should be avoided, this last week we kept locking up into a skid as we slowed to turn onto side streets, quickly backed the paddles off to level 1 and things were much more manageable and traction control and abs could do their thing like an ice car
 
I suspect that in time we'll all discover that the Kona is better than average in winter conditions. HOWEVER...the term winter conditions, covers a LOT of variations. I've driven my Kona on snow-covered roads and it was a monster, with no slipping whatsoever. Great traction and braking. Conversely I have driven on thin coated slush-slime and it was pretty dicey—understeering into turns and occasionally just breaking loose and sliding. In retrospect these behaviors are all similar to what I would expect from any ICE car. I also own a Honda CRV and even with all-wheel drive it handles nearly the same in the conditions I described above—great in packed snow, but but squirrely on slush and slime. In fact the CRV has on multiple occasions lost traction while decelerating quickly (like the Kona)...just from engine deceleration but only in certain "greasy" conditions. I personally always keep my regen level at one setting (3). I'm so accustomed to the feel of the car that I'm more likely to sense if the car begins to slip. Changing the regen levels alters the way the car normally handles which makes it much harder for me to "feel" the road.
 
Was driving in black ice conditions this morning. My default setting is Regen Level 3. As I was slowing down over a patch of ice (let off the accelerator and let regen slow me down), the car started slipping and ABS automatically kicked in and stopped my skidding (without me ever having touched the brake pedal). From my perspective, seems to work as expected (and desired).
 
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Jamas said:
Was driving in black ice conditions this morning. My default setting is Regen Level 3. As I was slowing down over a patch of ice (let off the accelerator and let regen slow me down), the car started slipping and ABS automatically kicked in and stopped my skidding (without me ever having touched the brake pedal). From my perspective, seems to work as expected (and desired).
Click to expand...
Well, that is very interesting, and contrary to some other posts. This is what I was hoping for actually, and really great if indeed this is how it works. Thanks for the report.

We haven't had any snow or ice yet where we live, so still have not had a chance to test this. But will be testing this carefully when it happens.
 
R P said:
Well, that is very interesting, and contrary to some other posts. This is what I was hoping for actually, and really great if indeed this is how it works. Thanks for the report.

We haven't had any snow or ice yet where we live, so still have not had a chance to test this. But will be testing this carefully when it happens.
Click to expand...
Just the snowflake above the odo reading on the dash display on my end.:D
But I think we might get acquainted with snow conditions later this week.
 
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