New Snow and Regenerative Braking

[Saghost]

With a little research I see that the Model S has an open differential, but is able to simulate limited slip differential behavior by applying the brakes in varying amounts to either wheel during acceleration. So it wouldn't be changing the amount of regen to individual wheels, but most likely applies the brakes independently to each wheel during regen to keep the rear end from sliding out. Stability control during regen braking. Maybe it also reduces the overall regen braking too, at the same time? Do you know if that's what it does?

I'm pretty sure that stability control is active at all times, so that might apply an individual brake to try to control a developing skid. I'm pretty sure that the car will reduce regeneration on that axle when it detects a slipping wheel.

I'm not aware of the car using the brakes/traction control to increase deceleration when it has to reduce regeneration due to a wheel slipping, but I don't know for a fact that it doesn't. I wouldn't expect it to.

One of the things I used to hate on my Volt was the odd feeling when it went over a big puthole during strong regeneration and the computer cut all regen for a second or so (while posting a "Low Traction" caution message) - the car seemed to lurch ahead.

I've read about that with the Prius too, but not on the Tesla cars, and my X doesn't do it - I'd assumed it's Tesla's more sophisticated traction control combined with using both motors to regenerate, but I don't know.

 

[AllenWong]

Thanks for the tip to turn off regen. P85DL here without winter tires but AWD. DO NOT drive this in the snow if you don't have winter tires even if you have AWD. My Tesla was slipping at 9 mph on unplowed roads. It not only felt like it was slipping, the indicator for slipping kept blinking and I was losing control of steering. And when I let go of the gas, the car was sliding and tires stuttering (probably regen + anti-lock brakes kicking in). The most I could do while it was snowing heavily in NYC was 15-20 mph. I thought that AWD would have at least allowed me to drive in the snow somewhat without winter tires. But this was not the case at all. Lesson learned.

 

[Saghost]

Thanks for the tip to turn off regen. P85DL here without winter tires but AWD. DO NOT drive this in the snow if you don't have winter tires even if you have AWD. My Tesla was slipping at 9 mph on unplowed roads. It not only felt like it was slipping, the indicator for slipping kept blinking and I was losing control of steering. And when I let go of the gas, the car was sliding and tires stuttering (probably regen + anti-lock brakes kicking in). The most I could do while it was snowing heavily in NYC was 15-20 mph. I thought that AWD would have at least allowed me to drive in the snow somewhat without winter tires. But this was not the case at all. Lesson learned.

You probably have summer performance tires. All seasons do better, if not that much.

 

[Robwoodruff]

They should have told you to buy snow tires if your car came with summer, racing tires. My S 85D came with the all year tires and they do great in the snow. The all wheel drive and traction control on this Tesla is much better than every car and truck I have owned over the years. This is my second winter and I have experimented a lot with the anti-lock brakes and regen to see what worked best. I have found that leaving regen on standard and feathering off the accelerator works very well to slow the car the fastest on ice. In fact, using the anti-lock brakes was much worse than regen. As soon as I put my foot on the brake, the regen stops working and the rapid pulsing of the brakes starts and I have the sensation of sliding; the car doesn't stop until I get to the bottom of the hill. I never get the sliding feeling as long as the four wheel regenerating is slowing down the car. Even going down a hill on ice, I was able to keep the wheels from locking up with the accelerator pedal and stop the car, could not do it with the brake pedal.

 

[AllenWong]

You probably have summer performance tires. All seasons do better, if not that much.

I'm pretty sure that's what I have, too. I don't normally drive my Tesla in the snow, because I'm usually in Florida in the winter. So I didn't bother getting winter tires, because I didn't think I'd ever need them. Also because I thought AWD would let me drive the car at least a little bit, but just not fast. I didn't know that it would cap me at around 15 mph. So I'm just giving other people a warning if they thought the same thing as I did.

 

[Barry]

AllenWong - With summer tires, your traction is compromised below 40F, even without snow. You're asking for trouble if you are going to spend any time in the North in the winter.

 

[AWDtsla]

I'm pretty sure that's what I have, too. I don't normally drive my Tesla in the snow, because I'm usually in Florida in the winter. So I didn't bother getting winter tires, because I didn't think I'd ever need them. Also because I thought AWD would let me drive the car at least a little bit, but just not fast. I didn't know that it would cap me at around 15 mph. So I'm just giving other people a warning if they thought the same thing as I did.

Summer tires have effectively 0 traction on any snow or ice. You can get stuck in a completely flat parking lot. I know, I've done it.