YYZ airport parking - vampire drain in freezing cold

[dusdev]

Left for a trip on Friday, Jan 11th ((Model 3 LR AWD). Coming in to YYZ from about an hour away (100 km). The morning of Jan 11th charged to ~95%, around 480 km range. It was cold. Ended up arriving and parking at the airport with 352 km range remaining (78% range efficiency).

Arrived back on Sat, Jan 19th. Range display showed 250 km. So effectively lost 102 km range with the car sitting there ~8 days (12 km/day loss). This seemed quite high to me. Coincidentally the car decided to download the 2018.50.5 firmware update over LTE while it was parked there. I got the update notification on Wednesday. I ended up launching the update on Saturday morning before my flight departed (after checking the range was sufficient to get home).

Anyway, I had enough charge to get home (return 100 km trip used 155 km range, or 64% efficiency). So I had more than enough for this round trip+parking but ultimately was somewhat disappointed by the 12 km/day range loss.

I knew there were some J-1772 chargers at YYZ as a backup. They are surprisingly low power at 6.6 kW. Didn't end up using them as I saw them as a waste of time.

TLDR: Round-trip to YYZ from 100 km away. Charged to 480 km. Returned back with 95 km. Parked for 8 days. Total range used: 385 km; actual distance traveled: 200 km. Lost 185 km for parking and cold effects.

 

[Struja]

I think the airport solution is an easy one... they need to install a lot of 120v outlets across the airport parking. I think level 2 chargers are overkill for most people, who usually travel in excess of 2 or 3 days.

Ideally, you could have pulled in with about 300km in range, plugged into an 120v outlet and wait until two days before you were scheduled to come home (if your range dropped to 200), you'd have 48 hours to get back up to your 90%. More than enough time.

 

[Derek Kessler]

Yep, that's sitting in the cold for you. The car will use the battery power to keep the battery warmed to what it thinks is a reasonable temperature. When it's cold and I'm parking at the airport for several days, I always plug in, even if it's just a 120V outlet on the wall.

 

[bijan]

Did you get the snowflake icon? If it's cold, part of the battery capacity can be inaccessible until battery warms up. So you might have lost 50km of range and lost 50km to the snowflake.

For example I charged to 447km on Friday night and ended up with 435km and snowflake icon the next day. But if I check the actual battery percentage from the Tesla web API it was the same (90%, but that extra 12km inaccessible).

 

[bijan]

Yep, that's sitting in the cold for you. The car will use the battery power to keep the battery warmed to what it thinks is a reasonable temperature. When it's cold and I'm parking at the airport for several days, I always plug in, even if it's just a 120V outlet on the wall.

I have not found this to be the case. It was -19C overnight and I had the same range and percentage this morning as when I parked last night (0% battery capacity loss and 0km range loss, 35% capacity and 154km range before and after). I lost 0% battery capacity overnight Friday, but range was 12km lower due to snowflake icon. And 1% battery capacity loss overnight Saturday.

But every morning when turning on car to drive got a message about the battery heating and power would improve as I drive. If it was using power to heat the battery when parked outdoors I would expect greater range losses overnight and/or not to have to further warm the battery when driving.

 

[Derek Kessler]

I have not found this to be the case. It was -19C overnight and I had the same range and percentage this morning as when I parked last night (0% battery capacity loss and 0km range loss, 35% capacity and 154km range before and after). I lost 0% battery capacity overnight Friday, but range was 12km lower due to snowflake icon. And 1% battery capacity loss overnight Saturday.

But every morning when turning on car to drive got a message about the battery heating and power would improve as I drive. If it was using power to heat the battery when parked outdoors I would expect greater range losses overnight and/or not to have to further warm the battery when driving.

That's just several hours, much of which your battery pack was still warm enough from prior night's driving. We're talking days of sitting. I've observed the same with my car, parked at the airport for several days during a bitter cold February with all the chargers occupied. Parked with ~120 miles on the battery, came back to find my car at under 20 miles (not nearly enough to make it home). Had to squeeze into a striped spot next to a Bolt and swipe its plug for several hours to get enough charge off the 120V/20A chargers CVG has in the garage. Security was very confused about why I was sleeping in the ticketing area at 3AM.

 

[bijan]

That's just several hours, much of which your battery pack was still warm enough from prior night's driving. We're talking days of sitting. I've observed the same with my car, parked at the airport for several days during a bitter cold February with all the chargers occupied. Parked with ~120 miles on the battery, came back to find my car at under 20 miles (not nearly enough to make it home). Had to squeeze into a striped spot next to a Bolt and swipe its plug for several hours to get enough charge off the 120V/20A chargers CVG has in the garage. Security was very confused about why I was sleeping in the ticketing area at 3AM.

It was 12 hours. Battery pack was not warm at all. Had severely reduced propulsion (dots on the right side all the way to under the numbers on the rated km/miles so more than half limited) and snowflake icon, doubt battery could have gotten colder.

Car will lose 10km or more a day just due to phantom drain even in summer. And snowflake icon due to cold will take away 50km of range (unavailable until car warms up).

 

[bijan]

If it was heating the battery you'd lose massive amounts of range. At 1kW you'd lose 100 miles a day. At 500 Watts you'd lose 50 miles a day. Any less heat than that and I doubt it could keep the battery warm. OP reported 10km (6 miles) a day loss over 8 days and when he got back it was probably -15C (5F). That's not much worse than summer phantom drain and some of that may have been due to the snowflake icon issue I described.

 

[dusdev]

There was a snowflake but I'm unsure how that affected the reported range. Because about an hour into my drive home, the snowflake went away but I didn't notice the range change significantly.

 

[dusdev]

I think the airport solution is an easy one... they need to install a lot of 120v outlets across the airport parking. I think level 2 chargers are overkill for most people, who usually travel in excess of 2 or 3 days.

Ideally, you could have pulled in with about 300km in range, plugged into an 120v outlet and wait until two days before you were scheduled to come home (if your range dropped to 200), you'd have 48 hours to get back up to your 90%. More than enough time.

I think having 120V outlets at a minimum is a great idea. I think it would alleviate some of the vampire drain anxiety. I know that the YYZ Park & Fly offers an EV valet service where they will complementary charge your car (apparently with Tesla HPWC) before you return. My friend used their service in December and came back to a 90% charged vehicle.

 

[TexasEV]

I don’t understand your use of the term “efficiency” to describe how much energy the car uses to travel in freezing weather compared to the EPA rated range. That has nothing to do with how efficient the car is. It’s just physics. Would you ever compare your mileage in an ICE in the winter to the advertised mpg and calculate a percent “efficiency “?

The J1772s output is not surprising at all. The 6.6 kW is 30A output on a 208V circuit. That’s what the vast majority of J1772s do, probably more than 95% of them, at least in the US. In Canada you have Sun Country Highway which is the exception of using high amp J1772s but high amp J1772s are rare otherwise.

 

[bijan]

There was a snowflake but I'm unsure how that affected the reported range. Because about an hour into my drive home, the snowflake went away but I didn't notice the range change significantly.

It seems to work as follows as far as I can tell. If you check the percentage battery vs rated miles you can find out how much capacity the snowflake caused to be unavailable. With the snowflake present is the only time when rated km does not equal battery percentage times a fixed multiplier. Rated km will be lower than that. As you drive the battery heats up and the unavailable capacity becomes available slowly, once all capacity is available or at least most of it, the snowflake goes away. But at the same time capacity is being used to drive. So rated km goes down but by less than the amount of kWh used. It's noticeable if a large enough amount of capacity is unavailable.

 

[dusdev]

I don’t understand your use of the term “efficiency” to describe how much energy the car uses to travel in freezing weather compared to the EPA rated range. That has nothing to do with how efficient the car is. It’s just physics. Would you ever compare your mileage in an ICE in the winter to the advertised mpg and calculate a percent “efficiency “?

Efficiency in this context is meant to be the percentage of actual distance traveled compared to the stated range....

From the dictionary:
TECHNICAL
the ratio of the useful work performed by a machine or in a process to the total energy expended or heat taken in.

Useful work: actual distance traveled

If you have better terminology I'm happy to use it though.

 

[ben1628]

That's just several hours, much of which your battery pack was still warm enough from prior night's driving. We're talking days of sitting. I've observed the same with my car, parked at the airport for several days during a bitter cold February with all the chargers occupied. Parked with ~120 miles on the battery, came back to find my car at under 20 miles (not nearly enough to make it home). Had to squeeze into a striped spot next to a Bolt and swipe its plug for several hours to get enough charge off the 120V/20A chargers CVG has in the garage. Security was very confused about why I was sleeping in the ticketing area at 3AM.

How does that compared to destination charger in one of options around YYZ? I think they will keep your car charged before you return.

 

[bijan]

I don’t understand your use of the term “efficiency” to describe how much energy the car uses to travel in freezing weather compared to the EPA rated range. That has nothing to do with how efficient the car is. It’s just physics. Would you ever compare your mileage in an ICE in the winter to the advertised mpg and calculate a percent “efficiency “?

This is a common calculation in cold weather since it is required to figure out if you will make it anywhere with the available battery capacity. Let's say I have 450km range and the next supercharge is at 170km away and the one after that 270km away. If I'm getting "50% efficiency" I'm going to have to stop at the closer one.

Also most of the extra energy in winter is "wasted" in heating the cabin and/or lack of regen, which is related to efficiency. That is how much energy is used to move the car a certain distance (vs how much is lost to heat and brakes). It's less efficient as less energy is recovered in regen and more energy is wasted in heating things.

You're right that we're not talking about how efficient the motor is though.

My ICE car gets 600km range on a tank in summer and 550km range in winter so I don't ever have to worry about it.

My model3 gets 200km vs 400km. This weekend with short trips and battery heating running it was even less than 200km.

 

[dusdev]

BTW - speaking of vampire drain, I've been wondering about how much of this is due to leaky power switches in the battery system. Low impedance switches are usually pretty leaky (they don't stop all the current when 'OFF'). The upside to this loss is much higher power transfer efficiency when they are actually drawing current. In other words, there is less loss in the switch during acceleration and forward motion. So in return for the awesome Tesla drive experience we may be paying for it with vampire drain. At least to some extent...

 

[bijan]

BTW - speaking of vampire drain, I've been wondering about how much of this is due to leaky power switches in the battery system. Low impedance switches are usually pretty leaky (they don't stop all the current when 'OFF'). The upside to this loss is much higher power transfer efficiency when they are actually drawing current. In other words, there is less loss in the switch during acceleration and forward motion. So in return for the awesome Tesla drive experience we may be paying for it with vampire drain. At least to some extent...

I think back of the envelope calculations indicate that the drain is 35W-70W when car is truly sleeping. So if that is on the order of the losses due to such a leaky switch then that could be it.

Drain when car is not sleeping but idle is closer to 250W if I remember correctly. Which might make sense for the whole computer system being ON. But 35W-70W is a little high for standby for background electronics (LTE system, etc.).

 

[TexasEV]

Efficiency in this context is meant to be the percentage of actual distance traveled compared to the stated range....

From the dictionary:
TECHNICAL
the ratio of the useful work performed by a machine or in a process to the total energy expended or heat taken in.

Useful work: actual distance traveled

If you have better terminology I'm happy to use it though.

Youre misinterpreting the “stated range”. It’s the EPA rated range, meaning the range on the EPA test cycle, with defined temperature and speeds (and no wind, or rain, or slush on the road, etc.). It’s not a projected range, or an expected range, or anything other than the range the car would get on the EPA test. Think of it as percent of charge if you take that number and divide by 310 rather than the number of miles you can expect to drive.

There’s no terminology for it that I can think of, other than saying when it’s freezing out you got 78% of the rated range. That’s a useful number for you to know for trip planning, but has nothing to do with the car’s efficiency.

 

[Blu-Ion]

My car is currently parked at YOW plugged into 120v outlet. That's all we need for long term parking. Simple solution to add a row of charging receptacles

 

[dusdev]

There’s no terminology for it that I can think of, other than saying when it’s freezing out you got 78% of the rated range. That’s a useful number for you to know for trip planning, but has nothing to do with the car’s efficiency.

I think that using the term efficiency is completely valid. If you set out with the same state of charge on different days, and you end up getting different distances, the difference ratio can be described as efficiency. Since for the same power (battery charge) you may get less or more distance. In other words, the power in the battery did not get you as far, hence there was an efficiency loss (or gain). It's completely valid engineering nomenclature in this situation.