Regenerative braking on icy roads

[UncleCreepy]

I have had more than one close call with this issue. It is literally criminal that there is no way to disable regenerative (read: uncontrollable) braking when conditions demand it. Hopefully it won't take a class action lawsuit for Tesla to move this to problem to the front burner.

When you let off the accelerator in slippery conditions and the immediate braking initiates a slide/hydroplane all you can do is pray.

Can you elaborate on that further? Like what happened, which car, do you have winter tires installed etc.

I'm asking because I always have my regen set to full and I've never had any problems in three winters with the Model 3, even if I suddenly take my foot of the accelerator. The electronics (at least in my car) reliably avoid the rear wheels locking up, much like ABS would if I used the friction brake instead.

I'm not trying to invalidate what you wrote, I'm just trying to understand how the personal experience can vary so greatly.

 

[tlt99]

Happened to me twice on brand new geminis and once with new snow tires on an icy surface. Where I live winter conditions can last 7+ months.

All I ask is for Tesla to add a simple on/off slider in the Driving tab to disable regen braking. What could be the argument against adding this?

 

[Corndart]

The most interesting part of this to me is how Tesla had people try to spread a bunch of battery fire FUD a few years back, and the response was a logical break down of how many battery fires there were compared to fires in ICE cars, along with some mitigation attempts by NERFing the battery packs on high mileage Model S's and also NERFing the battery packs on Model S's that had done a boat load of Supercharging.

If Chevy had said "yeah, a lot less Bolts burn up than Gasoline powered cars" they would be throwing their gasoline powered models under the bus... so they can't do that. The other option would be what they are doing as an interim measure. I am currently only supposed to use around 60% of my Bolts battery pack, never charging more than 90% and not letting it go under 30%. If they changed that to 20% and 90% (keeping it to less lose of range than covered by the warranty) and hard coded it via a mandatory software update on cars after they reach a certain mileage, or a certain number of kWh charged via DC fast charging they would be handling the situation the same way Tesla did. The problem is, they can't do it via over the air updates against the car owners will like Tesla can, and many people ignore recall notices and / or would actively choose to not have their battery pack NERFed. As MY owners we don't have a choice, the NERFing is automatic and built in... it isn't even triggered by a software update, it just automatically happens after you hit the Supercharging threshold.

Keith

Care to share pointers to more details regarding this behavior? Are you asserting this is also happening to MY batteries?

 

[Fourdoor]

Care to share pointers to more details regarding this behavior? Are you asserting this is also happening to MY batteries?

Here is a link to an electrek story on the subject:

Tesla explains why it limits Supercharging speed after high numbers of DC charges

The Tesla community had another small technical/communication controversy this week that was not unlike the controversy around Tesla’s undisclosed performance...

electrek.co

Keith

 

[Johnny Vector]

Here is a link to an electrek story on the subject:

Tesla explains why it limits Supercharging speed after high numbers of DC charges

The Tesla community had another small technical/communication controversy this week that was not unlike the controversy around Tesla’s undisclosed performance...

electrek.co

Keith

So, first of all, that article says nothing about Model Y, since the Model Y didn't exist when it was written.

Second, even if we assume current MY batteries are identical to the ones in a Model S six years ago, it still says nothing about reducing the battery capacity. The effect in question is to limit the maximum charge rate, which is a very different thing. That's the problem with using terms like "nerfing", which has no actual meaning. It's an ideal FUD term, because people can just interpret it in the worst possible way. So when I come across it now I just assume it means "playing the Buffy theme song".

Lithium-ion batteries age, get used to it. When the BMS says "She canna take 250 kilowatts at this age, cap'n," you'd best pay attention.

 

[jcanoe]

FWIW I have been experiencing reduced regenerative braking in the A.M. as the overnight temperature of the battery has dropped. My 2020 LRMY has the option to set Low regenerative braking. I tried letting off on the accelerator pedal at low speed (with reduced regenerative braking due to temperature) and Standard regenerative braking; then again with Low regenerative braking enabled. The deceleration was reduced, regenerative braking was further lowered, when I set regenerative braking to Low even when regenerative braking was already limited due to temperature.

In general I leave regenerative braking set to Standard. If I had to drive in the snow (I can usually choose not to drive in snow conditions) I would probably set regenerative braking to low.

 

[mikemarmar]

I found this interesting product and ordered a set: S3XY Buttons
Thinking of using two buttons to set up "regen paddles" on the left and right side of the steering wheel. Could be nice to be able to enable 0% regen on the highway too.

 

[tm1v2]

I found this interesting product and ordered a set: S3XY Buttons
Thinking of using two buttons to set up "regen paddles" on the left and right side of the steering wheel. Could be nice to be able to enable 0% regen on the highway too.

If anyone has tried that regen adjustment functionality on a 2021+ Y or 3 (without the touchscreen low regen option) I'd love to hear confirmation that it still works on newer cars!

I imagine there are less convenient debug tools that can trigger the same functions, if adjusting regen works via any of them on newer cars, it probably will via that button system too.

 

[mikemarmar]

My Y is a March 2021 build. I'll let you know if it works.

Edit -- The manufacturer claims it can be done:

 

[Fourdoor]

So, first of all, that article says nothing about Model Y, since the Model Y didn't exist when it was written.

Second, even if we assume current MY batteries are identical to the ones in a Model S six years ago, it still says nothing about reducing the battery capacity. The effect in question is to limit the maximum charge rate, which is a very different thing. That's the problem with using terms like "nerfing", which has no actual meaning. It's an ideal FUD term, because people can just interpret it in the worst possible way. So when I come across it now I just assume it means "playing the Buffy theme song".

Lithium-ion batteries age, get used to it. When the BMS says "She canna take 250 kilowatts at this age, cap'n," you'd best pay attention.

Good for you.

I didn't say anything controversial, someone asked for a source. I provided a link. Go yell at electrek for spreading FUD if you like.

Keith

 

[OxBrew]

I've been driving around in packed snow and ice for the last 2 days, and played with lifting off the throttle on hills, flat, everywhere. No issues at all. (Great snow tires installed.)

It's super easy to feather the regen as needed; if you're already used to one pedal driving, and have experience driving in the snow, this is a non issue. If you have neither, just go slow, you'll be fine.

Been driving a Subaru Outback in the same conditions for the last 16 years every winter. I always said the Outback with Blizzacks was like driving a tractor on velcro in the snow. So far, the Y beats it, by a lot.

 

[thesmokingman]

My Y is a March 2021 build. I'll let you know if it works.

Edit -- The manufacturer claims it can be done:
View attachment 741649

That's a pretty interesting product. They're essentially user programmable shortcut buttons.

Yea, definitely let us know how it works and make a thread or somehing.

 

[rjpjnk]

I found this interesting product and ordered a set: S3XY Buttons
Thinking of using two buttons to set up "regen paddles" on the left and right side of the steering wheel. Could be nice to be able to enable 0% regen on the highway too.

Wow! These look very interesting. I wonder what else they can control?
I'm not sure I'd feel comfortable having a device like this actively controlling stuff on my car via the CAN buss though. Could it possibly make some undesirable changes if malfunctions, like deploying the airbags for example?

 

[OxBrew]

Wow! These look very interesting. I wonder what else they can control?
I'm not sure I'd feel comfortable having a device like this actively controlling stuff on my car via the CAN buss though. Could it possibly make some undesirable changes if malfunctions, like deploying the airbags for example?

I highly doubt airbag deployment has any adjustment parameters available. I've not dug around at all in there, but other cars have effectively software-air gapped safety functions like that, can't be set even using dealer diagnostic stuff.

Not saying there's not a lot that can be set wrong and cause damage, I've seen software settings that could be flipped and grenade an engine, so sure, something could go wrong, but pretty unlikely.

The main thing keeping me out of there is Tesla's warning against it.

 

[mikemarmar]

The buttons just arrived and I tested them out. They do indeed work to disable/enable regen. It takes roughly 5 seconds for regen to ramp down to 0% and the same for it to ramp back up. It also remembers the setting across driving sessions and even across a Power Off. One little quirk: The button that sets regen to 0% actually acts as a toggle between 0 and 100% whereas the button to set regen to 100% is not a toggle. So, if you don't know what state you are in the most reliable way to turn regen off is to press the 100% button followed by the 0% button.

 

[mikemarmar]

I got the chance to take the car out in some of the worst possible conditions this morning on the way up to the ski hill. Wet snow had frozen onto cold road, outside temps were about 20F and there was a glaze of ice on the highway with a moderate dusting of snow on top. In anticipation of an upcoming icy section I eased off the pedal. The rear end immediately cut loose and started to fishtail. My ingrained response from almost 20 years of driving in the snow was to immediately lift off the pedal entirely, which I know is the wrong thing to do with regen braking but I did it before even realizing it. Thankfully traction control kicked in very quickly and righted the ship.

After that I turned off regen entirely and the rest of the drive was rock solid except for a little minor low speed fishtailing on the way up the canyon while under acceleration. Again traction control kept it in line.

 

[boulder.dude]

I did some in-town driving on icy roads this morning (first snow in 2 months here). Consistently, when I took my foot off pedal, regents kicked in causing the back end to slide, then about 1/2 sec later the car reduced regen to let the tire regain its grip. Disconcerting but not terrible. Bummer that it happened every time; can’t the car “remember” for the next 30min or until it is parked?

 

[lemkeant]

I got the chance to take the car out in some of the worst possible conditions this morning on the way up to the ski hill. Wet snow had frozen onto cold road, outside temps were about 20F and there was a glaze of ice on the highway with a moderate dusting of snow on top. In anticipation of an upcoming icy section I eased off the pedal. The rear end immediately cut loose and started to fishtail. My ingrained response from almost 20 years of driving in the snow was to immediately lift off the pedal entirely, which I know is the wrong thing to do with regen braking but I did it before even realizing it. Thankfully traction control kicked in very quickly and righted the ship.

After that I turned off regen entirely and the rest of the drive was rock solid except for a little minor low speed fishtailing on the way up the canyon while under acceleration. Again traction control kept it in line.

Thanks for the update, I was curious about this as I have a MYP on the way

 

[acatwith12]

Letting off the gas pedal enables full power regen. For my MY, this is ~82 kW of power in reverse at highway speeds with a warm battery. Hitting the brake pedal doesn't change this at all. Unfortunately for snow driving, this is 100% rear wheel braking. It didn't cause me any issues last winter though. ABS still keeps things under control.
View attachment 706650

this is cool, which app / how are you getting this data?

 

[pbcsd]

I got the chance to take the car out in some of the worst possible conditions this morning on the way up to the ski hill. Wet snow had frozen onto cold road, outside temps were about 20F and there was a glaze of ice on the highway with a moderate dusting of snow on top. In anticipation of an upcoming icy section I eased off the pedal. The rear end immediately cut loose and started to fishtail. My ingrained response from almost 20 years of driving in the snow was to immediately lift off the pedal entirely, which I know is the wrong thing to do with regen braking but I did it before even realizing it. Thankfully traction control kicked in very quickly and righted the ship.

After that I turned off regen entirely and the rest of the drive was rock solid except for a little minor low speed fishtailing on the way up the canyon while under acceleration. Again traction control kept it in line.

You turned regen off entirely... How? I thought Tesla removed the ability to turn off regen?