Cabin Heater in Blizzard

[Ofarlig]

Here's a snippet from a trip I made on the coldest day of the year. Car shows a temp of -32C, hvac set to 18C, 3 fan, both seat warmers on 2 bacon. In 10 minutes, we managed to travel 100m. Average power usage is 5.28kw and an estimated range of 95km... although it would take a whole week to do that at 0.6km/hour.

Question is, how hot was the car when you started this? Because it is WAY higher than my experience for a already warm car in -28 to -30C (HVAC at 21) in a model S, but it is in line with what I would see if the car wasn’t properly heated when starting the drive.

 

[Gasman23]

Tesla owners are seriously geeky

 

[brucet999]

So 1.5kW with fan speed one, 21C, with -19c or so outside. My guess is it was pretty chilly in the car. A little surprised it is that low, but keeping that fan speed low definitely restricts the output of the PTC. My numbers quoted (for 73/50 degrees, which were about the same 1.5kW) were basically full blast heat numbers, getting the cabin nice and toasty.

If you are trying to fend off death seems like you might be able to stretch the battery for a day or two.

I wonder how much difference the Evannex window heat shields made? If it cut heat loss in half, then it might have been 3kW without them.

Bjorn was heating probably twice the air volume in his Model X, open to the trunk for sleeping, as there would be in the cabin of a Model 3, so I would guess 1.5kW would be a good estimate for a stranded Model 3 without window coverings. How much battery energy capacity is there? At what SOC would the car shut down the heater to preserve battery?

 

[brucet999]

Elon Musk says 75kWh



At 20% there would be a message about conserving energy but not a complete shutdown even at 0% as seen in picture below.

"Heating and AC reduced"
I wonder how much? Still enough to be survivable if stranded in -20C weather?

 

[AlanSubie4Life]

How much battery energy capacity is there? At what SOC would the car shut down the heater to preserve battery?

A new car has 77.6kWh of capacity at 100%. No idea when it reduces heater output.

I wonder how much? Still enough to be survivable if stranded in -20C weather?

As others have said, gotta bring other survival equipment if those temperatures are possible. Having shelter that a car provides is pretty helpful though (for shelter from wind & elements and reducing heat loss). If you have warm clothing (and down sleeping bag, etc.) you could do ok for quite a while I suspect. Wouldn't be pleasant though. As they always say - stay in your car if you get stuck. Unless you REALLY know what you're doing.

 

[user212_nr]

On another forum, one of the posters, who lives in Maine, opined that a Model 3 could be "life threatening" because of limited range compared to an ICE vehicle. Further on, he asserted that, if trapped in a heavy snowstorm, an ICE driver could last days, idling the car to keep the cabin heating going, making sure to occasionally clear the tailpipe of snow, whereas a Model 3 would run out of battery after a few hours of cabin heating.

This is so dumb that it doesn't hardly deserve a response. You cannot reply on your car's engine in order to safeguard your life. There are some "ice road truckers" who would die if their trucks failed, but that is their line of work.

What people worry about most is an engine breakdown, and for that reason people are told to keep warm clothing in order to ride out the storm without the engine. Remember also that they might wreck the car, in which case they need to survive in the open air, exposed to the elements.

I can find ICE fuel efficiency and fuel tank size data easily, but I wonder how long such a car can idle on a gallon of gasoline?

How Much Gas Does Idling Use? - CAR FROM JAPAN

0.2 gallons per hour according to the above link (or less), so that makes 100+ hours.

I'll give the win to the ICE car, but this is not a serious situation. They can bury the Tesla in the snow and convert it to an igloo if they want.

There are a few people this has happened to, but its far out of the normal.

 

[brucet999]

This is so dumb that it doesn't hardly deserve a response. You cannot reply [sic] on your car's engine in order to safeguard your life.

So, your car just slid off a lonely, snowy road in to a ditch. It is -20F outside and 50 miles from the nearest town. Do you advocate trying to walk 50 miles, or just shut off the engine and wait?

 

[BabyYeggie]

Question is, how hot was the car when you started this? Because it is WAY higher than my experience for a already warm car in -28 to -30C (HVAC at 21) in a model S, but it is in line with what I would see if the car wasn’t properly heated when starting the drive.

The car was pre-heated to 21C. Then, we drove to and dropped off the kiddo at Montesorri. That involved a 15 minute break from driving. Then, we drove to work. Normally, it's a 35 minute drive but a combination of low temperatures and snow increased the commute time to 75 minutes. These 10 minutes was roughly half way in the trip where traffic did not move at all, so starting temperature doesn't matter much.

The secret to energy efficiency is actually moving...

 

[BabyYeggie]

So, at 5.28 kW average and creeping at .53 km/h, might we assume that heating load consumed maybe 5 kw of that? If so, then it would take 14 hours to use 70 kWh at delta T of 50ºC.
How big is Model 3 battery?
At what SOC does the car shut down cabin heater to conserve battery?

I have an SR+ so the useable is 49.8kwh with a 2.4kwh buffer, according to scanmytesla.

I'm going to assume cabin heater shuts down at 0% because I've drained the battery down to 2% and the heater was still working. It took 53 minutes to charge at 6kw with a Tesla charger at a random mall to put in 32km to make it to the supercharger.

 

[Ofarlig]

The car was pre-heated to 21C. Then, we drove to and dropped off the kiddo at Montesorri. That involved a 15 minute break from driving. Then, we drove to work. Normally, it's a 35 minute drive but a combination of low temperatures and snow increased the commute time to 75 minutes. These 10 minutes was roughly half way in the trip where traffic did not move at all, so starting temperature doesn't matter much.

The secret to energy efficiency is actually moving...

Well starting temperature matters a lot, if it is very cold outside the car takes quite some time to heat up completely and until it has more energy will be put into heating. The first hour of driving you will spend more energy than the second hour even if you preheated, add a break in the middle and you will just add extra "heat up time".

Your graphs show exactly this where the first few minutes have a higher energy usage than the later part. If you would have extended the graph for another 30 minutes im sure it would have dropped further.

Range for short trips will always look terrible in the winter for this reason, but the range gets important for the longer trips.