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Model S Car Crash Help for After Action Review

Hi friends, I'm a Model S Tesla P100DL owner and advocate. But I need your help. Let me explain what happened, and then I'm hoping that someone might have recommendations.

Live in Los Angeles, Tesla was 6 months old. Drove up to Mammoth Mountain for a few days of skiing. On the second day, it started to snow. I left the mountain early as I was concerned about driving in the snow with 19" Michelin factory tires (not snow tires). Temperature was cold (and car was out in the cold for 4-5 hours), maybe 20 degrees. Car had about 55 mile range as I was planning to charge it at the Tesla SuperCharger later that day.

Received a warning message on the screen that mentioned energy use is faster if batteries are cold. Began driving back to Mammoth Village. I generally use the regenerative breaking at max level to 'slow me down' and then brake only as required. I would say I got about 2 miles away from the mountain, when I rounded a curve at the crest of decent size hill, maybe 25-30mph ---not crazy driving since it was snowing, with 1/2 inch accumulation.

At this point, I felt regenerative braking stop, steering wheel became unresponsive--tried turning left but no response. Brakes were also unresponsive and the car slid sideways down the hill where it then crashed into a post around the right rear passenger door, and then forward into---of all my luck, a Mammoth Mountain Police Ford Expedition (he had pulled over a 2-wheel drive vehicle to wait for chains). Best way to describe the feeling is that it was as if the car completely shutoff on me and I was subject only to the laws of gravity and momentum. There must have been black ice underneath the 1/2" of snow, but it wasn't so much snow that snow plowers were out at that point...that came a few hours later.

I'm an old Army guy and we used to do what is called "After Action Review" to discuss and learn what should have been done, and what was done right. Now, two obvious points: winter rated tires and snow cables. In retrospect the winter tires make sense...but the car is a P100D on the factory 19" tires (tread was new). Is there something I should have done besides tires, cables or wait it out?

Appreciate folks' perspective, especially Model S drivers in climates where it gets cold and 'some' snow, but not so much snow that they are driving around in snow tires or cables.

The pictures are about 2 hours after the accident...took a while to get help. I realize it looks like a lot more snow accumulation at this point, but it was much less when I was driving.

Bottom line, you can see inside the cab, I walked away with just minor whiplash hitting the airbag, but otherwise only a minor scratch on my hand. Tesla definitely saved me...

Thanks all!
 

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croman

Well-Known Member
Nov 21, 2016
5,073
7,860
Chicago, IL
Ouch. Sorry. Glad you're ok.

Snow tires are the key. No need for chains if you've got good snow tires.

Stock tires are labeled all season but I find their snow performance, even with insignificant snowfalls, as deficient.

Your issue is further compounded by a cold soaked battery which likely limited your Regen braking and the fact you were going downhill.
 

croman

Well-Known Member
Nov 21, 2016
5,073
7,860
Chicago, IL
If the stock tires are that bad in snow I might change to a better all season. I hear there are a few good options.

No all season performs well in snow. That's why they have snow tires. The rubber in all season gets useless in cold and snow does not move through the treads, which means you lose traction. AWD won't help you if your tires don't work.
 

f3honda4me

Member
Feb 22, 2018
221
182
Colgate, WI
No all season performs well in snow. That's why they have snow tires. The rubber in all season gets useless in cold and snow does not move through the treads, which means you lose traction. AWD won't help you if your tires don't work.
There are plenty of all season I’ve used in AWD cars that did decent in snow. Of course snow tires are better, but good all seasons can suffice just fine.
 
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croman

Well-Known Member
Nov 21, 2016
5,073
7,860
Chicago, IL
If you had Michelin PSS tires on your car you basically had 4 hockey pucks.

Honestly, it is pretty irresponsible to drive summer tires in snow/cold. Not only are you putting yourself and your property at risk, but also others, evidenced by you hitting the police car.

Its easy to second guess. People make mistakes. That's why its called an accident. He didn't set out to crash into a cop car and he wants to know how to improve. I wish everyone took that approach to their mistakes instead of blaming others or shirking responsibility.
 

Eclectic

Member
Nov 8, 2014
792
1,404
Montana
Another vote for the wrong tires. Last month I was in Montana and had a Tacoma 4x4. It came with the OEM all season tires and I had a very similar experience to yours, but it was on the freeway. Between Bozeman and Livngton, at the pass, there was maybe an inch of snow on the road and more falling, with temps below freezing. I was in 4WD high with a pretty heavy load in the bed. As I went through a very gentle corner at about 45 mph the truck just lost control and I started to slide into the armco. I was able to recover before hitting anything that time but I lost control a few more times.

I've NEVER had that happen in similar conditions on my own truck, which has real mud and snow tires. I don't think you needed chains, just real M&S tires.
 
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Red_DS

Member
Mar 22, 2017
182
388
SoCal
Sorry to hear about the crash. I wanted you to know that I “liked” your post not because I like the crash, but because I like your attitude to learn from the accident.

As someone who works in safety, It’s refreshing to see when people take an open mind approach to understanding what went wrong and how it could be prevented.
 

GatorGuy

Member
Feb 25, 2018
529
544
Jacksonville
Its easy to second guess. People make mistakes. That's why its called an accident. He didn't set out to crash into a cop car and he wants to know how to improve. I wish everyone took that approach to their mistakes instead of blaming others or shirking responsibility.
I'm not trying to be mean to him but just give him the straight truth. As a military guy I'm sure he can take it. BTW, he hasn't confirmed that he was driving on summer tires so my comment may not apply.

But if someone was driving at night without lights, we wouldn't call that an accident. Nor if they were texting and driving or drunk.
 

McRat

Well-Known Member
Jan 20, 2016
5,771
6,077
LA
Don't surrender. Keep driving. aka - when in doubt, gas it. Give it some gas and saw the wheel center to left to center to left to unpack the tread and get the car to START to rotate. Once you get a little rotation, look for a safe place to crash, or an escape path. Locked up tires makes you passenger, keep the wheels turning.

Yeah, obviously more traction would have fixed it, but sometimes that's not an option. The same thing can happen wearing slicks on warm pavement.

Sign up for a defensive driving course that includes skidpan training. It won't fix THIS car but might fix your next car.
 
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Regenerative braking should be set to the low position in slippery conditions. The friction brakes need to be applied to get ABS braking.
With just regenerative braking if one wheel slips you have no braking because of the way a differential works.

Thank you... excellent insight. Did not think of turning regen to low. With certainty the brakes were 'cold' because I was not using them much, if at all during the two mile drive. I was thinking how brakes 'warm up' based on the friction...mine were likely cold/frozen.
 
Don't surrender. Keep driving. aka - when in doubt, gas it. Give it some gas and saw the wheel center to left to center to left to unpack the tread and get the car to START to rotate. Once you get a little rotation, look for a safe place to crash, or an escape path. Locked up tires makes you passenger, keep the wheels turning.

Yeah, obviously more traction would have fixed it, but sometimes that's not an option. The same thing can happen wearing slicks on warm pavement.

Sign up for a defensive driving course that includes skidpan training. It won't fix THIS car but might fix your next car.

Thanks great callout. Admittedly, driving the car for the previous 6 months with only a few days of rain, it's fair to say I didn't have much experience in the car on snow/ice. I think I was overconfident having lived in Chicago and NY years back. Good call on the skidpan training, thanks.
 
Sorry to hear about the crash. I wanted you to know that I “liked” your post not because I like the crash, but because I like your attitude to learn from the accident.

As someone who works in safety, It’s refreshing to see when people take an open mind approach to understanding what went wrong and how it could be prevented.

Thanks for your comments, definitely don't want to put myself, loved ones or strangers ever in that situation which was why I asked for help from everyone. My first reaction after the accident was concern for hitting the police vehicle and the officer inside. I was worried he was between his vehicle and the one in front (would have been smushed). Thankfully he was okay and not injured, and although he had every right to be upset at me, was a professional... called CHP to do the writeup at the scene. Although I didn't get a ticket, learned an important, if painful lesson.
 
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I'm not trying to be mean to him but just give him the straight truth. As a military guy I'm sure he can take it. BTW, he hasn't confirmed that he was driving on summer tires so my comment may not apply.

But if someone was driving at night without lights, we wouldn't call that an accident. Nor if they were texting and driving or drunk.

They weren't summer tires, but your point is valid... For sure I fell into the "this car is super technically advanced so it can handle anything" type of attitude. Let 'guard' down so to speak, and had a bad outcome that could have been really bad to others. Humbled to be sure... and of course glad I didn't hurt anyone.
 
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