Don't Trust Navigation Mileage in the Rain or Snow.

[Garlan Garner]

To whom it may concern,

I was driving back from Mississippi yesterday and I filled up my car with electrons in Effingham Il to the point where Navigation said that I would have an additional 20% of range when I arrived at my destination in the Chicagoland area.

150 miles from Chicago my additional mileage started dwindling and fast - once it started raining. Then it pretty much got all used up when it started snowing.

Well....15 miles away from my destination I only had 1% left. I was only 9 miles from the Country Club Hills SC when a RED ALERT popped up saying that I will have to charge before I got to that Supercharger. It was a nightmare, however I lived to tell about it.

So....for those who this may concern - During the winter / rainy / snowy days.….replenish your electrons far higher than what Navigation indicates.

Who knows....this may help someone not get stranded.....

 

[thelastdeadmouse]

I noticed during my Thanksgiving travels that the Energy screen's projected range was significantly more pessimistic than the navigation screen, it might be a safer metric to work off of.

 

[FloridaJohn]

Yep, I agree. Under 40 degrees F and rain really ups the required energy per mile. I had a leg of my trip this weekend planned for a long leg, but after an hour in the car it was clear that destination was not going to happen without an additional stop.

 

[usofrob]

I've seen slushy snow into the wind make my usage about double the rated range. Although usually in the winter I estimate using about 1.5x the rated energy over longer trips. During heavy snow, it seems reasonable to estimate 2x the rated energy.
If you use the energy graph, Tesla does a pretty good job of estimating your energy usage over the length of the trip for the current conditions after just a few miles. But, it nearly always estimates that you'll get to your next destination with more energy than actual. Once you start driving it updates pretty quickly to show you a more reasonable accurate measure.
Usually I drive a little slower in the beginning, then once I know I'm going to make it, I pick up speed.

 

[RDoc]

Seriously, watch the combination of cold weather, falling rain/slush, and a headwind. It can easily up your usage by 80%.

 

[Big Earl]

I make sure to check the wind and weather along my travel route on www.windy.com

I then plug that information into A Better Routeplanner to get a more accurate consumption estimate.

I was in the Outer Banks last week and we took a drive up to Nags Head for Thanksgiving brunch. The drive up was into a 25 MPH head wind. Estimated % remaining on arrival was 60% but ended up being 45%. The trip back to Avon didn't use much energy at all, thanks to the 25 MPH tail wind. ABRP was right on the money.

 

[WNYMike]

Had a similar problem when I was driving to relatives on Thanksgiving and it was about 10F outside. The trip there was about 70 miles but it ended up using about 120 miles of battery. A trip that should have been no problem on a full charge we decided to stop and use a supercharger before heading back, and I'm glad we did.
I don't remember where I heard this, but someone in another forum reported roughly a 1% drop in efficiency for every degree F under 40F, or something like that. This would roughly line up with what I experienced, though.

 

[Incredulocious]

I was driving back from Mississippi yesterday and I filled up my car with electrons....

Since we don't actually consume the electrons or get new electrons by recharging a battery, perhaps this cutesy phrase should be "I rearranged my car's electrons" or "I pushed all my electrons back" or ....?

 

[chillaban]

FWIW, I find it’s always a good idea to keep an eye on the energy estimation at arrival, and if it starts dwindling early on, start making adjustments then (either to driving style or to plan additional stops if present, reduce heating, etc). Adjustments made early on have a lot more of an impact than when you have that “oh crap” moment where the car tells you that you’re probably boned.

 

[TexasEV]

I don’t understand how anyone could disagree with the OP’s post. Rain and snow significantly reduce range whether you’re driving an EV or ICE. It’s just that no one cares about it in an ICE car.

 

[usofrob]

My Subaru also had an estimated range based on remaining fuel for the same reason. Gas stations remain more prevalent, I just needed to do a manual search on my phone to find them instead of being automatically directed to the charging station. And nearly all gas powered cars start with more range than my P3D+. (My Lotus Elise actually has very similar real world range of about 280 miles. But that's the worst I know of.)

 

[ewoodrick]

So, how long did you ignore the "You need to reduce your speed to X to make it to your destination"?

 

[Garlan Garner]

Since we don't actually consume the electrons or get new electrons by recharging a battery, perhaps this cutesy phrase should be "I rearranged my car's electrons" or "I pushed all my electrons back" or ....?

Really?

 

[Garlan Garner]

So, how long did you ignore the "You need to reduce your speed to X to make it to your destination"?

Didn't ignore it. Found a CP charger.

 

[whatthe2]

FWIW, I find it’s always a good idea to keep an eye on the energy estimation at arrival, and if it starts dwindling early on, start making adjustments then (either to driving style or to plan additional stops if present, reduce heating, etc). Adjustments made early on have a lot more of an impact than when you have that “oh crap” moment where the car tells you that you’re probably boned.

Yep, my battery showed 270 fully charged this morning but energy showed 202. It was 22 degrees in Denver this morning so seems much more accurate.

 

[Garlan Garner]

Yep, my battery showed 270 fully charged this morning but energy showed 202. It was 22 degrees in Denver this morning so seems much more accurate.

Very interesting.

 

[whatthe2]

Very interesting.

Yeah, I drove to the airport later in the morning after it warmed up to 35 or so and didn’t check to see if the delta had changed. I’m sure it did a bit. Will have test this when I get back home. Thanks for sharing.

 

[Incredulocious]

Since we don't actually consume the electrons or get new electrons by recharging a battery, perhaps this cutesy phrase should be "I rearranged my car's electrons" or "I pushed all my electrons back" or ....?

Really?

I’m not sure what you mean by “Really?”. If you’re annoyed with my comment or being sarcastic then my apologies to you. My comment was just meant to be fun to think about another amusing way to talk about what’s going on with those electrons. Definitely not meant to be a nit-pick – hence the smiley.

If you mean “Really?” as in you’re asking if it’s true that electrons aren’t added or removed in charging/discharging, then yes. The answer is yes. They’re just moved about in the process of propagating electrical current or in recharging the battery. And, perhaps more interestingly, the electrons actually move very slowly (like 80 cm per *hour*!). It’s the current or electromagnetic wave that’s propagated at near the speed of light. (See the web for more info if you’re interested.) So recharging the batteries isn’t adding electrons, it’s just moving them around to make it possible for the battery to deliver electrical power again.

 

[ecarfan]

I was driving back from Mississippi yesterday and I filled up my car with electrons in Effingham Il to the point where Navigation said that I would have an additional 20% of range when I arrived at my destination in the Chicagoland area.

150 miles from Chicago my additional mileage started dwindling and fast - once it started raining. Then it pretty much got all used up when it started snowing.

Garlan, you’ve been active for a long time on TMC and I thought you would have been aware that Tesla navigation does not factor in weather (rain, snow, extreme temps, headwinds) to any significant degree when calculating range remaining immediately after a route is entered. It never has, and still doesn’t. This has been discussed many many times on TMC over the years. What you describe is no surprise. In inclement weather one should always ensure a larger range buffer than in fair weather. I’m glad you didn’t get stuck.

Rain and snow significantly reduce range whether you’re driving an EV or ICE. It’s just that no one cares about it in an ICE car.

Agreed. ICE drivers (and we all were, once) just find a gas station somewhat earlier than they would have otherwise. And gas stations generally are pretty easy to locate.

 

[ICE FREE]

I have had my Model s 75D for 2 1/2 years, and I’ve always noticed a mild decrease in range as the temperature drops, as expected.

We just took delivery of our second Tesla just a couple of days ago, my wife’s M3 LR RWD and I’ve noticed that her car seems to consume more energy than mine. She’s not an aggressive drive at all and I’ve notice that her car has been using about 25% more energy than mine, according to the energy graph. It’s a little concerning to me.