Regen limited due to cold today

[Zextraterrestrial]

The difference is ICE behavior does not change while driving a particular vehicle. The noob S driver gets in, feels the strong regen on the A pedal, gets used to it, then suddenly next time they get in expecting it it's gone. I think at least a more strident warning is necessary, I have little faith in the abilities of some of my fellow drivers...

That is not true though. Try and 'floor' some gas cars that are cold and they may choke and stall. Or an automatic that tries to shift gears when you floor it and it doesn't just 'go'
this is just as bad as lifting your foot off the accelerator and expecting a car to stop. What if you are in a manual and the it pops out of gear when you are expecting a downshift to second to slow you (some used to do that! not necessarily under 'normal' conditions) it is practically the same thing .

 

[AnOutsider]

While it's fresh in your mind, can you please pass this information and a rough date-time for when you observed it along to one of your Tesla contacts in e-mail? Hopefully they can correlate this to telemetry data and/or pull logs from your vehicle to see what happened.

I'm curious whether it's a software/firmware issue, a sensor issue, or some other kind of malfunction.

This could be very valuable information in making all of our vehicles behave properly long-term.

Thanks!

brianman,

I just sent an email into ownership (not sure where else to put it), and also mentioned the wiper and charge port issues. Hopefully it reaches the right eyes.

That is not true though. Try and 'floor' some gas cars that are cold and they may choke and stall. Or an automatic that tries to shift gears when you floor it and it doesn't just 'go'
this is just as bad as lifting your foot off the accelerator and expecting a car to stop. What if you are in a manual and the it pops out of gear when you are expecting a downshift to second to slow you (some used to do that! not necessarily under 'normal' conditions) it is practically the same thing .

Whether it happens in other cars or other situations doesn't really change the fact that here, in the Model S, it is unwelcome behavior (for me anyway). It's not about how Tesla or the S is inferior, the same as, or superior to other vehicles... I'm more interested in Tesla making the car as good as they can, and for me, consistent behavior on the pedals would be a plus. (and yes, if I were engine-braking in a manual and it popped outta gear essentially leaving me in neutral, I'd find that to be unwelcome as well).

 

[Zextraterrestrial]

I do prefer the regen to work first thing in the morning because I have go up ~ 15 feet out of our road then down 100 foot hill & back up ~85 feet

And no, the S shouldn't be compared to other cars. my bad.
The little regen line is nice but It would be better if it could dump the heat or energy to the cabin or frame when it is limited and give the same decel - agree

 

[strider]

Whether it happens in other cars or other situations doesn't really change the fact that here, in the Model S, it is unwelcome behavior (for me anyway). It's not about how Tesla or the S is inferior, the same as, or superior to other vehicles... I'm more interested in Tesla making the car as good as they can, and for me, consistent behavior on the pedals would be a plus. (and yes, if I were engine-braking in a manual and it popped outta gear essentially leaving me in neutral, I'd find that to be unwelcome as well).

But it is relevant. The "complaint" is that this is different to how an ICE works and therefore will cause accidents. It's true that braking in an ICE isn't affect by cold but tons of other things are. As Zex pointed out, with older cars they barely run when cold. What if someone was pulling out into traffic and the car stalls? There's no light on the dash to tell you that you have reduced power when cold in an ICE - you just learn that as part of learning to drive. Reduced regen in an EV will just be something you learn as a driver.

My point is not to belittle the complaint. Yes, it will be great if we can solve this problem. My point is that it has taken a ton of advancements in ICE technology (fuel injection, faster computers, etc) over decades to improve cold-driving behavior. EV's will need some time to do the same.

I do think better notification is a good idea but I do not wish to add complexity by having the car add in friction brakes or anything.

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The little regen line is nice but It would be better if it could dump the heat or energy to the cabin or frame when it is limited and give the same decel - agree

Uhh... do you know how large and powerful a 60kW heater is? You'd be a crispy critter http://www.sears.com/qmark-electric-heater-high-temp-480v-60kw-by/p-SP101A26020S6351652104?prdNo=19#desc

 

[Doug_G]

The first time my Roadster turned off Regen due to cold (and I mean completely OFF), I didn't notice the light on the console. There's a yellow REGEN with X through it light. I didn't notice it because whenever it's cold you get that stupid "ICY" symbol lit up yellow (hate those things - like I don't already know it's cold???), so with a quick glance I didn't notice anything out of the ordinary.

Anyway, completely unaware I drove to the parking lot exit, took my foot of the pedal, and HOLY CRAP the car is rolling! It was so frictionless, and so different a feel, that it almost seemed like it was taking off on me. Naturally I immediately hit the brakes, and a split second later I realized what happened and looked at the console to confirm.

So for a novice user, it would probably be a good idea to have a more "vocal" warning if the regen is lowered by more than half. But that's a feature I'd really want to turn off once I was used to the car.

 

[JRP3]

Those of you describing a malfunctioning ICE for comparison rather make my point, and braking issues are more likely to lead to an accident than weak acceleration or stalling. Even in older vehicles a properly functioning choke meant those were rare occurrences anyway. In all my years of driving older vehicles in a cold climate I rarely experienced anything like what is being discussed, and it was more of an inconvenience than anything else. Doug-G describes the potential issue quite well, and in my own car I've experienced the same thing when I had controller problems that killed the regen unexpectedly.

 

[mknox]

Those of you describing a malfunctioning ICE for comparison rather make my point, and braking issues are more likely to lead to an accident than weak acceleration or stalling.

While I'm not sure this is going to be a big issue for me, I can see the point being made. If you get used to "one pedal driving" and sometimes the braking element isn't there, I could see one rear-ending another vehicle in traffic or similar. I had an experience years ago with wet brakes. When I pressed the left pedal and nothing happened, it was a heart-stopping moment until the friction dried the brakes out and the car stopped. You expect things like that on snow or ice, but when it happens "out of context" it can be a real scary moment.

I wonder if this is why most EVs and Hybrids rely on the brake pedal activating re-gen? You're already on that pedal, and if re-gen is limited, you just keep pressing.

Maybe a future software update could let you select how you want the re-gen to work (i.e. from the accelerator or from the brake pedal).

I've already started to wonder if I want to lower the re-gen setting in winter so I don't lose traction if I back off the accelerator too quickly on slippery roads.

 

[dsm363]

I would think a large warning message that pops up for a few seconds (that can be closed by the driver and even disabled completely as was said above) would probably be enough saying
'Warning: Regenerative breaking decreased until battery temperature increases. There will be less braking provided when you lift off the accelerator'

 

[jerry33]

I didn't notice it because whenever it's cold you get that stupid "ICY" symbol lit up yellow (hate those things - like I don't already know it's cold???),

I would have liked to have had one of them when I lived in Vancouver. It would help to know if the shiny stuff on the streets is rain (so BAU) or black ice. There is no much difference in temperature between the two states.

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Other OEM's somewhat avoid this by having less regen on the A pedal and putting it on the brakes.

No, it just shifts the no-regen to the brake pedal. Of the two, it's way less scary to have the no regen on the accelerator and have the brakes work then to go from rengen braking to no regen braking. (This usually happens going down a steep hill).

 

[Doug_G]

I would have liked to have had one of them when I lived in Vancouver. It would help to know if the shiny stuff on the streets is rain (so BAU) or black ice. There is no much difference in temperature between the two states.

I always think it's curious when people in mild climates like Vancouver and Halifax refer to "black ice", because I've never seen black ice under those conditions. Must be some other differences in the climate.

The black ice we get here happens when its -20C or colder and windy enough to blow around dry snow. The previously completely dry road - no snowfall is required for this - gradually and incrementally accumulates a ridiculously thin layer of ice. Passing vehicles actually help polish it up nicely. Once it's formed the only clue that it's there is that the road looks a little blacker than normal. If you're not watching out for it you suddenly discover that you have no traction whatsoever. The stuff is incredibly slick.

Found this - Black ice - Wikipedia, the free encyclopedia

Back to your regularly scheduled topic...

 

[strider]

Those of you describing a malfunctioning ICE for comparison rather make my point, and braking issues are more likely to lead to an accident than weak acceleration or stalling. Even in older vehicles a properly functioning choke meant those were rare occurrences anyway. In all my years of driving older vehicles in a cold climate I rarely experienced anything like what is being discussed, and it was more of an inconvenience than anything else. Doug-G describes the potential issue quite well, and in my own car I've experienced the same thing when I had controller problems that killed the regen unexpectedly.

And in your example it was a malfunctioning EV. I had a similar experience as Doug although mine was due to my first range mode charge. This thing with limited regen is it's something that happens ONE TIME and then you know what it is and it's never a problem again. I mean, who is doing 50 mph out of their neighborhood or following another car so closely such that a lack of regen would cause an accident? If so you're driving WAY too close to the edge and decreased regen is not the reason you crashed. As I said before Tesla should make the warning more prominent, be sure to highlight it during the delivery and in the manual and move on.

 

[Brian H]

I always think it's curious when people in mild climates like Vancouver and Halifax refer to "black ice", because I've never seen black ice under those conditions. Must be some other differences in the climate.
...

Scenario is recent rain, then a quick drop below freezing, often well below. The wet roads get that thin ice layer instead of drying off. Often occurs in patches, so traction goes from good to zero to good again unpredictably. Nerve-wracking.

 

[eledille]

Doug_G:

In Norway we often get both variants. We can get black ice even when the temperature is a few degrees above freezing due to water being able to cool to below freezing without turning solid if there are few impurities to start the crystallization process. This can happen during a temperature inversion - warmer rain is falling through a cold layer of air near the ground. It can also sometimes happen if the ground is colder than freezing and it's raining, but I believe the former variant is the more common. We call it "undercooled rain". It looks like rain, but it freezes immediately upon hitting the ground.

In my experience, this type of black ice is more slippery than the cold weather variety, but cold weather black ice has scared me at least as badly. As you said, it has to be really cold for it to form, so you're used to reasonably good traction. You can be driving along in nice weather suspecting no harm and all of a sudden you find yourself whipping the wheel this way and that catching skids and counterskids. Scary stuff.

 

[mnx]

I mean, who is doing 50 mph out of their neighborhood or following another car so closely such that a lack of regen would cause an accident? If so you're driving WAY too close to the edge and decreased regen is not the reason you crashed. As I said before Tesla should make the warning more prominent, be sure to highlight it during the delivery and in the manual and move on.

Totally agree. The regen just isn't that strong on the Model S to begin with.

 

[lgagliardi]

Left work last night and came to a stop sign expecting regen and did not have it. Was not told about it at delivery and did not read it (my fault) but you need to make it dummy proof. How the car stops should be communicated loudly - not just in the manual, that is way more important than if your radio did this or that. I was caught off guard. Now that I know, I will be ready for it but it sure would be nice if the issue just did not exist.

I just cannot get over how nice this car really is. I am just blown away by it and absolutely just enjoy driving it! For a first time car from scratch, they hit a homerun. I have been purchasing stock since early on, now that I have the car, I am not selling the stock.

Sorry for getting off thread.

 

[Robert.Boston]

The little regen line is nice but it would be better if it could dump the heat or energy to the cabin or frame when it is limited and give the same decel - agree

Key point. As I understand the issue, the motor is perfectly capable of regenerating the power, but Tesla doesn't want to route the power into the battery because it would overload the cells' charging at their current temperature. Why not route that power into the resistive heater for the cabin, or into the heating elements for the battery?

 

[JRP3]

As mentioned previously, what do you think a 60kW heater would look like?

 

[Zextraterrestrial]

As mentioned previously, what do you think a 60kW heater would look like?

something like a coil. Hot tubs have 2.5 - 7 kW coils. It wouldn't be that big but there is nowhere good for it to go. Couldn't you dump heat to the frame of the car though?

 

[arg]

It wouldn't be that big but there is nowhere good for it to go. Couldn't you dump heat to the frame of the car though?

It's a lot of energy: whatever you dump it to is going to get mighty hot. You don't want the frame of the car getting that hot - neither for the structural integrity of the frame, nor from the point of view of heating up all the things attached to it.

The logical place to put such a dump resistance is in the front wheel wells: both because there's airflow there (outflow from the much lower temperature radiators for the existing cooling systems), and because that's exactly where the heat gets dumped already if you don't use regen (ie. in the brake discs). In principle, the dump resistance needs only to be comparable size to the brake discs, but also needs to be able to withstand the same very high temperatures - not infeasible since they are typically made of the same material (steel). More of an objection really is the cost and complexity of additional wiring/power electronics to route the power there.

 

[Robert.Boston]

The energy is in the system (your car) and needs to be dissipated somehow during braking. Currently, with limited regen, you heat up your brake discs, which are almost always up to the job. This suggests that the total amount of power we're talking about isn't vast.

In any case, a variant of my proposal is to make sure that existing systems to heat the cabin and the battery are fully used, providing more regen capability.