How Long Would Battery Last? [hypothetical - sitting in gridlock]

[AKinDC]

I was reading about horrible Highway gridlock in Virginia during a big snow storm…drivers were stuck for hours and hours not moving, people were running out of gas and abandoning cars.
Let’s say you got into the gridlock with 250 miles of range…how long do you think the car would last without dying?
Assume you’re not moving, turn off the heat, and just use the seat heater for warmth.

 

[TexasTezla]

Many many hours...I'll leave the mathematical calculation to others...

Tips for staying warm in your Tesla this winter without killing battery range

As we near the winter months and temperature begins to drop across various parts of the world, Tesla owners living within cold climates will inevitably resort to their vehicle’s onboard climate control settings and seat heaters to stay warm. But understanding how much power each component...

www.teslarati.com

 

[GtiMart]

Having a heatpump will change the situation a bit. In my Model 3 without a heat pump I typically see a couple kW of consumption while sitting at a red light, once the cabin has heat up after a bit of driving. Using 2-3Kw consumption with a usable 70kWh battery, it would take 23-35h to go from full to empty.
A typical gas car seems to have around 12 gallons of fuel, and idle consumption ranges from 0.15-0.40 gallons/h for cars to 0.5-0.8 gallons/h for trucks (Fact #861 February 23, 2015 Idle Fuel Consumption for Selected Gasoline and Diesel Vehicles). They would empty their full tanks in 30-80h and 15-24h respectively.

Just averages but you get the idea. People don't always have their tank full, nor their batteries. I would venture to say gas cars will risk it more and drive with quarter tanks often to save a trip to the gas station whereas EVs will more often have a ~70% battery... just a guess.

You can save some energy by using seat heaters instead of ac/heating, they can stop their engines for a few minutes at a time and still have some heat.

 

[KenC]

Well, besides carrying a first-aid kit, you should always carry an emergency kit which has a space blanket, food and water. Use the space blanket and seat heater, and you might go for a couple days.

 

[jrweiss98020]

Worst case scenario: Heater uses 6kW, which is the highest draw of anything other than the traction motors. If you have a near-full battery, you could run the heater full blast for 12 hours. However, you would never do that, because it would cook you.

Take that to a 25% duty cycle (which I think is conservative for Camp Mode in 30 deg outside temp), and you'd get 48 hours on a near-full battery, or 12 hours on a half charge.

 

[ThomasD]

When they forecast bad weather coming even if it is a small chance I make sure my vehicles are full. In winter I have a snow shovel blankets, Water even if frozen it will melt when put near the heater. Throw in a couple of snacks to.

 

[jkirkwood001]

The advantage of an EV is that you can use heating only proportionately to extend the battery. In other words, you could heat the cabin only to a tolerable, well above freezing 10°C (50°F) which doesn't use the max heater and uses little energy. In a gas car, the motor is either idling "full", or off. So you don't have the granularity to create only partial heat with an ICE.

I have no idea how long 50 GWh of battery would last set to 10°C if it was, say -20°C outside.

As the wait got longer, you could reduce heat even further to 5°C (41°F) to extend the battery. You can't do this with an ICE.

 

[GtiMart]

Theoretically you can extend the ICE car's heating ability as well. When you stop the engine, you still have warm air for a couple minutes, from the coolant that's close to the exchanger. Once that gets cool you can start the engine for a very short period of time to circulate the coolant and bingo, a new batch of hot coolant for another couple minutes. It requires starting/stopping the engine manually every couple minutes, something no one does. I've done that when waiting on kids in my car sometimes, based on environmental concerns.
EDIT: Before someone asks: no, I do not know exactly how much fuel that saves. But I do remember an article that stated that when idling at a red light more than 10 seconds, it was better to shut the engine off. Never did that at lights but I remember.

 

[pnwadventures]

Would really like to hear from anyone who was actually stuck in that situation in a Model 3.

 

[jsmay311]

Many many hours...I'll leave the mathematical calculation to others...

Tips for staying warm in your Tesla this winter without killing battery range

As we near the winter months and temperature begins to drop across various parts of the world, Tesla owners living within cold climates will inevitably resort to their vehicle’s onboard climate control settings and seat heaters to stay warm. But understanding how much power each component...

www.teslarati.com

I know the OP mentioned turning off the cabin heat, but be careful with that source if looking at the figures in that article for heating the cabin. Those figures were from tests done on a Model S in 50F temps. So the heated seat and steering wheel consumption figures are probably reasonably accurate since those power consumptions will be mostly independent of ambient temps, but the cabin heat figures (particularly the one about heating the cabin to 74F) are pretty much useless for applying to a hypothetical situation where you’re stuck in freezing temperatures.

 

[MG535]

Worst case scenario: Heater uses 6kW, which is the highest draw of anything other than the traction motors. If you have a near-full battery, you could run the heater full blast for 12 hours. However, you would never do that, because it would cook you.

Take that to a 25% duty cycle (which I think is conservative for Camp Mode in 30 deg outside temp), and you'd get 48 hours on a near-full battery, or 12 hours on a half charge.

12 hours on a half charge wouldn’t be much comfort to the people stuck for 24 hours like yesterday in VA.

Plus anyone on a trip approaching their next SC was probably at 20% or so.

 

[jkirkwood001]

Theoretically you can extend the ICE car's heating ability as well. When you stop the engine, you still have warm air for a couple minutes, from the coolant that's close to the exchanger. Once that gets cool you can start the engine for a very short period of time to circulate the coolant and bingo, a new batch of hot coolant for another couple minutes. It requires starting/stopping the engine manually every couple minutes, something no one does. I've done that when waiting on kids in my car sometimes, based on environmental concerns.
EDIT: Before someone asks: no, I do not know exactly how much fuel that saves. But I do remember an article that stated that when idling at a red light more than 10 seconds, it was better to shut the engine off. Never did that at lights but I remember.

When the ICE is sitting 'off', where is the residual heat from the engine going? Not into the cabin! It's warming the air on top of the hood. Very wasteful.

Now maybe it still gets more heat into the cabin per % of fuel / battery, but but.. argh! ICE is so inefficient!! /rantoff.

 

[whiskeylover]

Now maybe it still gets more heat into the cabin per % of fuel / battery, but but.. argh! ICE is so inefficient!! /rantoff.

ICE is decently efficient at converting fuel to heat. Not very efficient at converting fuel to kinetic energy though.

 

[jrweiss98020]

12 hours on a half charge wouldn’t be much comfort to the people stuck for 24 hours like yesterday in VA.

Plus anyone on a trip approaching their next SC was probably at 20% or so.

My mistake - that would be 24 hours on a half charge.

 

[smartypnz]

Would like to hear from that white Tesla that was on the Wash Post website (sitting on the side with a tow truck backing up to it) - no, the caption wasn't focusing on that. Also there was a story yesterday in the Post specifically focusing on EV vs ICE in that situation and mentioned a family that in the middle of the night approached a Tractor trailer for water and food - battery had depleted.
When I lived in that area (not known for frequent winter disasters), I still carried a blanket, bottle of water, small shovel, and bag of coal or rock salt.

Although not necessary here in Central Coast California, I had visions of those days last week on a trip to Santa Clarita, where if I had not checked my route before leaving would have been stranded on the Grapevine in that situation (completely no weather warning). Luckily, I quickly diverted thru Santa Barbara/Ventura)

 

[spord]

Bjørn Nyland has some great videos on this topic on YouTube.

 

[rpiotro]

I did a little experiment to see what the current draw was like. Read my post here and do the math to get a rough estimate. May be able to keep the cabin at 60°F for 20 hours at least with a near full charge.

Precondition car plugged in vs not plugged in

Or the Value you place on One Peddle Driving... I love one peddle driving...

teslamotorsclub.com

 

[whiskeylover]

Dirty Tesla posted a video on this very same topic today.

 

[pl8dlikafiddle]

EV owners need to inform themselves on the pertinent parameters so that they are better prepared to deal with situations like this.

1. Know what a kilowatt (kW) is and the difference between "it" and a kilowatt-hour (kWh).
2. Know how to calculate how many kWh your car THINKS it has - the car gives you the parameters to calculate this on the energy screen. [(average consumption X miles remaining) / (state of charge - percentage)] X (0.95). For example, my 2020 LR AWD currently thinks it has roughly 69,4XX kWh when "full".
3. Know what car you have and get familiar with heater consumption - whether you have a resistive heater or heat pump.
4. Be prepared to turn your heat down and use seat heaters.

Many here are brushing it off - this may not be as big of a deal for local commuting where you're more than likely will have sufficient charge to last you a while (50% +), but this is a real risk for EV drivers on long road trips. Take into account the use of the car during interstate travel during road trips - the majority will be between 10-50% state of charge. 7-10hrs when you're 35-50% state of charge is workable, but if you're sitting at 20% when you get stuck, and it's escalates to the Virginia I-95 situation or the Atlanta "Snowmaggedon" where folks were stuck for 12-24hours, it's a bad deal that results in a dead EV.
I've got a trip from Atlanta, GA up to Lexington, VA at the end of January. Make no mistake I'll be bringing thick blankets and relying on my seat heaters if something similar occurs - and while I normally charge 5-10% past recommended during winter, I may extend that up to 20% just in case.

 

[GtiMart]

You are spot on. We tend to ride between chargers at low SOCs to optimize for speed when doing longer trips. In the winter, it might be better to charge a bit more than you need as a safety buffer. People on local commuting would have closer to 70% available.

I also think people should understand what kW and kWh are. I see a lot of people talk in terms of miles/hour of charging for example, and that doesn't make sense as it depends on the car's consumption. You should be looking at power provided by the charger, power added to the battery etc. Then you can start to understand power consumed by accessories. It's all fairly simple once you accept it and learn it. The Tesla UI could be better at showing this. They chose to "keep it simple" but in cases like this it's not necessarily beneficial.