Trapped in snow hypothetical

insular1

While watching cars struggle to make it up the hill outside my house yesterday a question popped into my mind.
Supposing you got stuck in a snow drift in the middle of no where with a nearly full battery how long could you expect the car could run the heating for before battery died?

Anyone know roughly how long an ICE could maintain heat on a nearly full tank?

goz83

Too vague a question. Be it petrol, diesel, or ev, the variables are many. Cabin size, engine/battery size. Temperature selected. Outside temps. Car insulation.

insular1

Hmm ok let's say a 24kw leaf as (probably?) the most common ev in Ireland. In current temps what draw is there on the battery to maintain 20c if everything else is off?

goz83

Ok well I guess the heat to maintain 20c would draw ~2kWh so with a full battery (22 usable) that’s 11 hours.

Idling a diesel for that long couldn’t be good for it.

ted1

Has anyone being stranded at home do to loss of power causing an inability to charge

Calahonda52

ted1 wrote: »

Has anyone being stranded at home do to loss of power causing an inability to charge

No, the reverse, using the battery to keep the internet and gas heating going

OldMrBrennan83

This post has been deleted.

insular1

11 hours, plenty of time for a rescue! That's better than I thought. Thanks!

GreeBo

In the absence of high winds/wind chill you would be better off outside the car.
Car acts like a fridge and will suck the heat out of you and make you colder. (Obv once the battery is dead!)

KCross

goz83 wrote: »

Ok well I guess the heat to maintain 20c would draw ~2kWh so with a full battery (22 usable) that’s 11 hours.

I dont think it would need a sustained 2kW to maintain the heat based on the output I see in LeafSpy.

It uses that initially to get up to the temp but it would be using ALOT less than 2kW after that so I'd say it would last several days but I dont know exactly how long.

GreeBo

KCross wrote: »

I dont think it would need a sustained 2kW to maintain the heat based on the output I see in LeafSpy.

It uses that initially to get up to the temp but it would be using ALOT less than 2kW after that so I'd say it would last several days but I dont know exactly how long.

A lot easier to heat to 20c when its not -11c outside!

Orebro

You'd hardly bump it to 20 degrees in such a situation? Surely 17/18 would be plenty and extend the battery time even more.

unkel

KCross wrote: »

I dont think it would need a sustained 2kW to maintain the heat based on the output I see in LeafSpy.

It uses that initially to get up to the temp but it would be using ALOT less than 2kW after that so I'd say it would last several days but I dont know exactly how long.

+1

I'd say an average of a few hundred watts would be plenty to survive and be reasonably comfortable (in your winter cloths), so then you are talking 4-5 days. Melt the snow and drink it and anyone can do without food for a few days no bother.

Not so sure how long a petrol / diesel would last with a running engine. Anyone any idea?

GreeBo

unkel wrote: »

+1

I'd say an average of a few hundred watts would be plenty to survive and be reasonably comfortable (in your winter cloths), so then you are talking 4-5 days. Melt the snow and drink it and anyone can do without food for a few days no bother.

Not so sure how long a petrol / diesel would last with a running engine. Anyone any idea?

I thikn you are massively underestimating the energy required to keep something warm in the current temperatures.

There is no effective insulation in a car, so the heat is not going to last, it will be sucked out of the car *and you* very quickly.

https://www.heatershop.co.uk/roomcalculator?confirm=&roomwidth=2&roomlength=2&insulation=N&zone=B&north=Y&calculate=Calculate#MainContent

460W to heat a 2x2 room to 21C

KCross

GreeBo wrote: »

I thikn you are massively underestimating the energy required to keep something warm in the current temperatures.

There is no effective insulation in a car, so the heat is not going to last, it will be sucked out of the car *and you* very quickly.

https://www.heatershop.co.uk/roomcalculator?confirm=&roomwidth=2&roomlength=2&insulation=N&zone=B&north=Y&calculate=Calculate#MainContent

460W to heat a 2x2 room to 21C

460W is a lot less than 2kW though. thats the point.

GreeBo

KCross wrote: »

460W is a lot less than 2kW though. thats the point.

Its a lot easier to heat a room than a metal car sitting in -11C is my point.

You seals will shrink allowing cold air inside
You will need to crack a window so you dont poison yourself, again allowing cold air in.

pablo128

Carry a shovel with you along with suitable clothes hat and gloves. A bit of shovelling will warm you up quickly and you might even be able to free your car and continue your journey.

unkel

unkel wrote: »

............

Not so sure how long a petrol / diesel would last with a running engine. Anyone any idea?

Well loads of stuff will return 50mpg when cruising at 60 ish mph.
55l / 12 gallon fuel tank would then let you cruise for 10 hours.
Considering you'd be at 2000rpm ish and be encountering aerodynamic issues and lugging the car about obviously I'd think it logical enough to presume that at idle (800rpm) the thing could go for 3 or 4 times as long
So 30/40 hours.

liamog

GreeBo wrote: »

Its a lot easier to heat a room than a metal car sitting in -11C is my point.

You seals will shrink allowing cold air inside
You will need to crack a window so you dont poison yourself, again allowing cold air in.

Car's aren't sealed enough to have a risk of poisoning if you leave the heating on.

GreeBo

liamog wrote: »

Car's aren't sealed enough to have a risk of poisoning if you leave the heating on.

Its either sealed enough that the build up of CO2 (not carbon monoxide) will cause you problems OR its not sealed enough and so you will freeze.

You cant have it both ways

pablo128

GreeBo wrote: »

Its either sealed enough that the build up of CO2 (not carbon monoxide) will cause you problems OR its not sealed enough and so you will freeze.

You cant have it both ways

There are usually 1 way vents in the quarter panels.

GreeBo

pablo128 wrote: »

There are usually 1 way vents in the quarter panels.

So either you are getting fresh air or you are not.

Fresh air will be sub zero.
Stale air will have increasing levels of CO2.

pablo128

GreeBo wrote: »

So either you are getting fresh air or you are not.

Fresh air will be sub zero.
Stale air will have increasing levels of CO2.

Recirculating air in a car will contain approx 5% fresh air. Believe it or not, car makers spend millions developing vehicles to be used in all types of conditions. They will have realised a thing or 2 about heating in cars over the last 100+ years.

GreeBo

GreeBo wrote: »

So either you are getting fresh air or you are not.

Fresh air will be sub zero.
Stale air will have increasing levels of CO2.

With the heating on the air is coming in through a pollen filter or not through a pollen filter.

As said if on recirc you are still getting some fresh air as part of the mix.

The fresh air you mention is heated before it gets into the cabin That's what the ole heater thing does

GreeBo

Augeo wrote: »

With the heating on the air is coming in through a pollen filter or not through a pollen filter.

As said if on recirc you are still getting some fresh air as part of the mix.

The fresh air you mention is heated before it gets into the cabin That's what the ole heater thing does

Agreed, but this air is well below freezing, so heating it to aint cheap.

Add in the heatloss through the complete lack of any insulation and I think people talking about a few hundred W are way off the mark.

Thankfully I will never need to find out.

goz83

GreeBo wrote: »

Agreed, but this air is well below freezing, so heating it to aint cheap.

Add in the heatloss through the complete lack of any insulation and I think people talking about a few hundred W are way off the mark.

Thankfully I will never need to find out.

The OP said to use current temps. Its not well below freezing in dublin. I was in the car earlier and outside temp was 4 above.

GreeBo

GreeBo wrote: »

Agreed, but this air is well below freezing, so heating it to aint cheap.

Add in the heatloss through the complete lack of any insulation and I think people talking about a few hundred W are way off the mark.

Thankfully I will never need to find out.

I'm not bladdering on about a few hundred W .........just pointing out that you were totally incorrect with the "You will need to crack a window so you dont poison yourself, again allowing cold air in." speel

GreeBo

Augeo wrote: »

I'm not bladdering on about a few hundred W .........just pointing out that you were totally incorrect with the "You will need to crack a window so you dont poison yourself, again allowing cold air in." speel

I didnt say that you were. Unless you consider yourself to be "people"?

goz83 wrote: »

The OP said to use current temps. Its not well below freezing in dublin. I was in the car earlier and outside temp was 4 above.

Weather over the last few days has dropped below -5 at night.

GreeBo

Also, most of the air isnt coming in through a vent, unless you believe your car is airtight other than the air vents...?

Freezing air will be coming in everywhere.

pablo128

GreeBo wrote: »

Freezing air will be coming in everywhere.

No it won't ffs. If it was, there would be thick ice on the inside of every car parked overnight by now.

GreeBo

GreeBo wrote: »

Also, most of the air isnt coming in through a vent, unless you believe your car is airtight other than the air vents...?

Freezing air will be coming in everywhere.

So with the fan on most of the air will be coming in from "other than the air vents"?

Did you ever drive with no fan on and the car fogs up?
Why would it do that?