Official Cold Weather Driving Thread (Tips, Tricks, Tears)

[jwardell]

Going on a long drive in subzero temperatures can certainly be surprising if you don't prepare for it.

-Air density is much higher and causes more drag, especially as you drive faster. Ask any pilot.

-Batteries can not be charged at ALL below freezing, and regen is reduced linearly below room temperature. So you will lose regen with a cold battery, or you will waste energy heating it. Precondition the battery before you leave when still plugged in (if Rivian implements this) to help.

-Likewise the battery must be near balmy to achieve high power DC fast charging. You are in for a rude awakening pulling into a fast charger on a very cold day and realizing your 20 minute charge turned into an hour. Tesla eventually added preconditioning when navigating to a supercharger to help this, and I hope Rivian does the same (otherwise, heat things up by driving like hell)

-It takes a *LOT* more energy to heat the cabin from 20 to 70 degrees than cooling from 90 to 70. Especially if it has a resistive cabin heater and not a heat pump.

But... my Model 3 is still the best winter vehicle driven BY FAR... Because most of the time, one tap of my phone 5 minutes before I leave and everything he preheated and ready to go. Also because traction control in EVs is orders of magnitude more reactive than ICE and driving in the snow is effortless and like you're on rails.
Preheat, and just account for 25% less range or drive a bit slower.

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[crashmtb]

-Batteries can not be charged at ALL below freezing, and regen is reduced linearly below room temperature. So you will lose regen with a cold battery, or you will waste energy heating it. Precondition the battery before you leave when still plugged in (if Rivian implements this) to help.

news to me, I’ve charged a Tesla at -35c ambient.

 

[jwardell]

news to me, I’ve charged a Tesla at -35c ambient.

Pack temp, not air temp

 

[crashmtb]

Pack temp, not air temp

If your battery has cold soaked you’ve got bigger problems, I reckon.

 

[jwardell]

If your battery has cold soaked you’ve got bigger problems, I reckon.

It's cold soaked every morning... the pack is a massive thermal mass and cold windy winter nights will easily bring it well below freezing, and even if you jump in for a drive hours later it will still be extremely cold if you don't precondition.

I should have mentioned, those of you lucky enough to have garages, even if unheated, will have a much better time with an EV in the winter

 

[sub]

My Tesla model 3 has a battery pre-heating feature and I have not found much value in it.

It does make a huge difference for the first few miles. If you are going on a short trip around town, it can make your consumption look like it is a warm summer day even when it is sub-zero outside.

But for driving around town, there is no benefit to that. You end up using more electricity(overall) just to get home with a battery that is at 75% instead of 70.

The only time range matters, on a road trip, the impact of preheating is pretty small. The boost you get from pre-heating the battery only lasts about an hour, after that your consumption is the same as it would have been without pre-heating. I would guess that pre-heating the battery before you hit the road saves less than 5 minutes at the charger.

 

[flabyboy]

It isn't 40%. That was the average between sport and conserve mode. Clearly if you are going for range you'd be in conserve mode.

Also later on in the post someone posted the test process, thats starting from cold, ie no preconditioning while plugged in. Also keeping the cabin at 72 degrees. It was also the city driving test, I'm sure there are differnces with that too.

It isn't a real world number, this thread is a bit too chicken little for me.

Probably not going to drive my truck in FWD a lot in bad weather conditions. I’m sure I will use it on the highway during warmer weather, but part of the reason I’m getting a truck is because of the bad roads in these parts

 

[DucRider]

As scary as the 40% number is, it's better to go in with eyes open rather than have it bite you later.

I personally think the 40% represents close to a worst case scenario. Preconditioning and more judicious use of the cabin heat (use the seat heaters!) will go a long way toward mitigating that number for most folks.

314 is not a magic number that you will always get when you drive your R1T. Sometimes it will be better, sometimes it will be worse. Under extreme conditions, it will be a lot worse.

ICE vehicles turn 70% plus of the energy contained in gasoline into waste heat. Diverting some of that heat to the cabin comes with essentially no penalties. Not so on EVs where only a little waste heat is generated (at one point Rivian planned to capture some of that - don't know if it made it to production). The heat to keep you comfortable comes at the direct expense of range. You're using energy from the battery to keep warm. This is ALWAYS something I relay to people first learning about EVs. It takes EVs off the table as an option for some, but better before purchase than finding out afterwards.

Other factors reduce range in cold weather, but heat is the biggie.

 

[yizzung]

Clearly if you are going for range you'd be in conserve mode.

If I wanted to drive a 2WD EV through snowy mountain passes I would own a Nissan Leaf.

 

[SeaGeo]

Being able to precondition and heat that battery up while plugged in will be a big help when people can (assuming Rivian has that enabled somewhere being just cabin heating).

 

[yizzung]

ICE vehicles turn 70% plus of the energy contained in gasoline into waste heat. Diverting some of that heat to the cabin comes with essentially no penalties. Not so on EVs where only a little waste heat is generated (at one point Rivian planned to capture some of that - don't know if it made it to production).

Doing a little digging:
https://www.slashgear.com/rivian-r1t-cold-weather-testing-commences-in-frigid-minnesota-01661699/

Don't know if this made it into production vehicles but the quote seems like it's pretty integral to the design?

Unlike other modern EVs with electrical heaters that add weight, cost, and consume a lot of energy, the Rivian R1T has a unique thermal management system that utilizes the inverter and motor to generate heat when the vehicle is parked or stationary. Meanwhile, the system recovers waste heat to warm the batteries while the truck is running.​

 

[Rhidan]

Just wear your ski gear in the car and turn off the cabin heat. No need to dress-up when you get to the bottom of the hill. Two birds; one stone.

Pre-conditioning should help out greatly. You really just don’t want to park outside in the cold at night without being plugged-in. That EPA number is after they cold-soak the vehicle for 24 hours

 

[yizzung]

Just wear your ski gear in the car and turn off the cabin heat. No need to dress-up when you get to the bottom of the hill. Two birds; one stone.

Pre-conditioning should help out greatly. You really just don’t want to park outside in the cold at night without being plugged-in. That EPA number is after they cold-soak the vehicle for 24 hours

Test procedures cold soak the vehicle for 12-36 hours at the 20 degrees F (-7 degrees C).
Cabin conditioning set to 72 degrees F on auto for all seating positions
Test is performed at a constant 20 (+/- 1) degrees F.

Yeah, I'm feeling a little better after a bit more education on the subject. (This is my first EV and I had never heard the term "cold soak" before today...)

The 40% hit is eye-poppingly terrifying but I will never head out into a snowstorm after a cold soak. Will have chargers at either end of my journey. So no cold soaks for me but I'm still very curious what kind of range penalty to expect with, uh, warm soaks?

I had read this post from Rivian (https://stories.rivian.com/cold-weather-testing) and just assumed, whelp, these people clearly get it. Shouldn't experience any problems! That article in hindsight doesn't really say much.

They talk about great performance on snow but don't say what driving mode they're using. (Wild guess: it ain't Conserve Mode.) And they don't say much about battery performance hits or how to combat them. I presume this advice will be forthcoming.

 

[crashmtb]

It's cold soaked every morning... the pack is a massive thermal mass and cold windy winter nights will easily bring it well below freezing, and even if you jump in for a drive hours later it will still be extremely cold if you don't precondition.

I should have mentioned, those of you lucky enough to have garages, even if unheated, will have a much better time with an EV in the winter

Does the tesler not have battery heating?

 

[Lobstahz]

To echo @sub 's comments, here are my stats on my 2018 Model 3 AWD. I have the least efficient Model 3 AWD before the heat pump, so it will have toaster-heat (more accurately resistive heating) just like the Rivian. I run blizzaks as my winter tires which are quite sticky as far as winter tires go, and run wider than stock sticky summer tires which is certainly a factor in these low efficiency numbers.

Below is all drives over 10mi by temperature. Random anecdote ... sadly reminded me I haven't been skiing since my oldest arrived 3 years ago.

My point is - I imagine the range hit projected is likely accurate to slightly aggressive (real life will be less of a hit) but better to prepare for the worst.

@yizzung you mentioned you have destination charging on both ends, so your likely worst case scenario will be a really quick charge mid-trip (he said assuming one is on the way) as you can roll in relatively low (as low as you feel comfortable) and be confident you'll be charged when you need you car next.

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