EV cars and the I-95 weather mess

No EV experience so I'm curious how they would be different in the midst of the stoppage on I-95 earlier in the week.  In a combustion car, you turn it on, run the heater for a while and then shut off and repeat the cycle until the gas runs out.  Is anything different behavior in an electric car?  Would the batteries provide heat longer?  Shorter?  Certainly "fuel" level dependent but let's assume as many cars stopped for gas as recharging so the same distribution of fullness.  Random thought driving home from work tonight.

glueguy (Forum Supporter) said:

Is anything different behavior in an electric car?   Would the batteries provide heat longer?  Shorter? 

No not really.  It depends on the size of the battery and the draw of the heater.  So a battery with 25 KWh (2/3 the capacity of a Nissan Leaf) of usable power in the cold could run a 1KW heater continuously for about 24 hours.  If you used a blanket and a 50w heated seat, you'd be looking at more like 500 hours.

The answer is unfortunately "it depends" on a lot of factors

• battery size
• state of charge
• equipped with heat pump or no
• ambient temp
• length of time stuck

I believe EVs use anywhere from 1-4 kw to keep the cabin at an even room temperature. So if you're stuck somewhere for 10 hours, figure you'd need anywhere from 10-40 kwh of battery to stay at 68 degrees inside. 

I think a Tesla with a reasonably full battery would have been fine on I-95, and I suspect some stuck were Teslas, so maybe we'll hear about it. A LEAF driver would have been in a tough spot. And you wouldn't have to worry about carbon monoxide poisoning.

I personally stash a heated blanket that plugs into the 12V outlet in my car in case of situations like this. 

Depends on the type of heating used for the EV, too. Some are more efficient than others. Most efficient is heated seats because it's better to heat the meat than the air.

Ironically, newer gas vehicles will be worse at this sort of thing as they're more efficient than older ones, so less of their energy is wasted as heat. Although it's not waste in this case :) Still pretty bad, though, so lots of that gasoline energy is available as heat once the engine warms up.

All you're really doing is just trying to keep up with heat loss and you've got people acting as heaters at the same time. I wonder how much heat is really required for that? Cars aren't very well insulated overall but it's a small space.

In both cases, once you're out of energy you're going to get cold and you don't have access to the ability to add more energy.

In reply to Erich :

Better to carry a candle in a jar and a space blanket. That's what was in my cold weather box in my Subaru back when I used to camp in the mountains mid-winter.

In reply to glueguy (Forum Supporter) :

Old Buick LeSabre answer:  Run the car and crank the heat so high, that you can't stand it.  Then, turn off the car until it is freezing cold in the car again.  Then, resart and repeat.  

Toyota Prius answer:  Set the climate control to a temp.  In interest of saving fuel, that temp might be 60 rather than the 72 degrees you'd really like.  The hybrid system then turns on the engine automatically as needed to maintain that 60 degrees constantly.  My Prius is a great car to "wait in" for this reason.  You get exacting comfort with really no effort and really little fuel consumption.  

Full EV answer (I think):  Either do the Buick version of high heat and then no heat by turning on and off the HVAC system.  Or, do the climate control version and set to 60 degrees and let the car itself decide when it turns on or turns off the HVAC.     

Off topic - I watched that on the news and there's one guy that filled up before he got on and there's the guy on E who said we'll fill up at the next exit.   

The bread truck guy got a million dollars of good will advertising.  

John Welsh said:

In reply to glueguy (Forum Supporter) :

Old Buick LeSabre answer:  Run the car and crank the heat so high, that you can't stand it.  Then, turn off the car until it is freezing cold in the car again.  Then, resart and repeat.  

Toyota Prius answer:  Set the climate control to a temp.  In interest of saving fuel, that temp might be 60 rather than the 72 degrees you'd really like.  The hybrid system then turns on the engine automatically as needed to maintain that 60 degrees constantly.  My Prius is a great car to "wait in" for this reason.  You get exacting comfort with really no effort and really little fuel consumption.  

Full EV answer (I think):  Either do the Buick version of high heat and then no heat by turning on and off the HVAC system.  Or, do the climate control version and set to 60 degrees and let the car itself decide when it turns on or turns off the HVAC.     

Full EV answer is do the climate control version. I doubt there's an EV on the market that doesn't have auto HVAC. It's not like it's difficult when you have full control over the HVAC anyhow :)

Note that heat loss is proportional to the heat differential. So the LeSabre cranked up to 90F inside will lose heat faster than the Prius sitting at 60. Better to fire up the Buick more often for a shorter period.

Erich said:

I personally stash a heated blanket that plugs into the 12V outlet in my car in case of situations like this. 

I have a car that the 12V outlets don't work unless the engine is running.

In reply to Pete. (l33t FS) :

This is in an EV, so "running the engine" doesn't cause any appreciable fuel loss unless you're running the heater. It's a big blanket so it would cover the kids in case of emergency. I should probably get some emergency snacks and water in there too. 

In a full EV, doesn't the battery have to maintain a certain temp? Or is that only during charging and hard use?

I'd hate for the battery to run down faster as it tries to save it self from freezing.

In reply to Gearheadotaku (Forum Supporter) :

yep, it doesn't take much energy typically to maintain the battery temp though. 

I feel like the real answer is to pool resources-  Get 4-5 other motorists together and just utilize body heat thermodynamics and stick together in one vehicle, exhaust those resources, then move on to the next...  I think that's got to be the most efficient way to ride something like this out for the longest possible duration, no?  

I know covid and the whole stranger danger thing are big variables on this here, but I was surprised to not see or hear any of this happening.  It makes so much more sense to me to do it that way... 

Relevant video I ran across, short answer is that keeping it indoor-toasty would've cut it close, but setting it to just a safely cool temperature would've been no problem at all:

I have played with W/Mile consumption on cold road trips to Detroit.  The seat heaters are vastly more efficient than running the HVAC.  Keeping the HVAC at a reasonable temp had far less impact on energy.

My wife saw the i95 nightmare unfold so we jetted off on 295 through VA to the 301 Potomac river bridge. We still stopped for several hours with downed trees in a hybrid Highlander...so not totally relevant to this thread. I had 1/2 tank of fuel when we ground to a stop. I was watching the gauge like a hawk doing calculations of fuel burn per hour. In hybrid mode, I was surprised by some judicious power cutting, how little fuel we used in the carnage. We had about...1/2 tank when we started moving again. 

And yes...the seat heaters are fantastic. 

The breathless reporting on this is making me doubt any reporting I read. Multiple ICE cars had to be towed away, out of gas with no means to provide heat for the occupants. An EV is at least equally capable of heating the passenger compartment while stuck in traffic or any other emergency. I suspect most every EV would outperform most ICE cars in a measure of "sitting there not moving with the heat on for as long as possible" competition.

I won't link the article, but I saw one this morning about a Tesla with a broken heater, and how it was cold without the heater. Yup, in an EV, things break, too. I've had ICE cars with broken heaters, and you all have as well. Why report on that? I have seen multiple articles with titles like "Tesla owners worry about the upcoming winter" as if this was winter #1 for electric cars.

Anyway my Bolt is doing fine in the winter. Here's the thing about winter: It's cold sometimes. Plan for that.

At least in an EV, you don't have to worry about CO poisoning while it's heating the cabin

Serious question, would an EV be a lot better than an ICE if you were stuck outside of Flagstaff in 105-degree heat? IIRC, some EVs have solar panel roofs and cooling fans to keep dogs safe. Seems like you could use the A/C and fans during the day and heat at night for a few days if you had some solar recharging.  

red_stapler said:

glueguy (Forum Supporter) said:

Is anything different behavior in an electric car?   Would the batteries provide heat longer?  Shorter? 

No not really.  It depends on the size of the battery and the draw of the heater.  So a battery with 25 KWh (2/3 the capacity of a Nissan Leaf) of usable power in the cold could run a 1KW heater continuously for about 24 hours.  If you used a blanket and a 50w heated seat, you'd be looking at more like 500 hours.

This.  Its pretty simple.

One thing to note is in an ICE car I suspect the lowest possible heat output you can get is in excess of 1KW.  When sitting still in VA with the heat on pretty much any setting will eventually cook you out of the car.

When you are somewhere cold enough that the minimum heat output no longer suffices, I bet the ICE will outperform, given equally full "tanks".

Here's a graph from energy.gov

Gasoline has about 33 kwhr/gal.  So at a 0.18gal burn rate, thats 5.94kwhr being used.  ~1/3 of that escapes via the cooling system.  Even if you only need 500w of heat, your radiator will dump out the other 1.5kw.

This is why I agree with John's ICE approach of run the heater on full blast, let it cool, run it again.  Edit.  Keith is right that stopping it at a lower max temp will probably save some energy.  Although an additional cool down of the powertrain will be siginificant as well.  How much heat is lost there?  Didn't some nerd around here do some calculations on that?

Still, if you have a full tank, it appears an ICE will run a long time even wasting heat.

The best would probably be a hybrid that had smart enough thermal management to run the engine for just enough to heat the coolant, then shut off until the coolant temp gets too low.  

Then again, when it is cold enough, the heater core can effectively provide 100% of engine cooling, so maybe not?

ICE engines are better at making heat than they are making power, so idling in a snow storm is playing to their strengths :) I'm tempted to leave the Tesla outside with the HVAC running next time we have a cold night and see what the energy use looks like. Janel might have a problem with that.

I've slept overnight in my old Subaru while skiing in CO. Naturally, I was using proper gear like a down sleeping bag rated to -5F. One morning, I drove down the mountain to Crested Butte to find out that I was in the coldest place in the US. I don't recall there being ice on the inside of the windows - people are remarkably effective space heaters. There might have been some uncomfortable folks but this was likely not too dangerous.

I did that Keith, but it wasn't that cold. In the 30s I ran the HVAC most of the night along with my CPAP and seat heaters. I think it used something like 2 miles of range.

https://insideevs.com/features/559482/anti-ev-opinion-not-true/