Canadian winter - best practices for preconditioning battery for best efficiency?

[KOZMONAUT]

I know that this topic is discussed to death, but I am wondering about those -20c to -35c days, setting a scheduled departure prior to leaving and then warming the car up fully while on wall power is the best "normal" method to drive.. But what if I wanted to add some more heat to the battery?

From what I understand, preconditioning via scheduled departure brings the battery up to 15c as a target, which is not that warm, and in those real cold days still barely gets me full regen or if it does it's only for 10 minutes. Driving on those cold days seems to essentially lose temperature (wish I had a scanmytesla to verify) while driving. Also, from what I understand, preconditioning the car to supercharge targets 60c.

What I am thinking, is that because the battery is such a large thermal mass, and it gets better efficiency in general when its warm, and the heat pump instead of being in "heating mode 5" (heating both the cab and battery while driving), if the battery was already warm it could focus on just the cab and use less KW in general... I am wondering if somehow preconditioning for a supercharger while at home plugged in would give better efficiency for a long time while driving.

I am thinking the easiest way would be hop in the car, turn the climate control to OFF, then setting navigation to a supercharger (this is after it had a scheduled departure and maybe an hour before I leave so the battery is decently warm), and getting out but not fully shutting the door but instead leaving it open a crack... This would fire up the motors and heat pump to warm the battery to supercharger temperatures, then maybe 15 minutes before I leave I turn the climate on, hop in, and go.

This would allow it to pull 8KW (SR+) from the wall all towards the battery heating and because it's such a large thermal mass, having it at that 30-40c+ instead of the 15c from scheduled departure would get me much further, and allow me to do less supercharging, and since my home power is so cheap, it would be a lot cheaper in general for those 400KM round trips in winter.

Does any of this make sense? Has anyone tried this? Another way to get it to precondition manually would be having one of those S3XY Knobs, and that has a button to manually precondition... I think I'd still have to leave the door cracked.

 

[KOZMONAUT]

Can't figure out how to edit my post.....

But I just hopped in the car and I got it to precondition but if it's plugged in it will not. I wonder if those S3XY buttons or knob would be able to bypass this.

 

[Soul Surfer]

Can't figure out how to edit my post.....

But I just hopped in the car and I got it to precondition but if it's plugged in it will not. I wonder if those S3XY buttons or knob would be able to bypass this.

The app should allow you to do it. Also you can use the app to schedule departure, which will engage pre-con.

 

[Regaj]

Our winters here in the mid-Atlantic are certainly much milder than what you see up north. But I've monitored pack temps in many conditions (with SMT) and what I can say is that the only scenario where I have ever observed pack temps declining while driving is following a Supercharger session (where pack temps will peak around 65C/150F, or a bit more), when the car is actively cooling the pack.

Model 3's (and I assume all Tesla's) have negligible pack cooling from airflow while driving. I have not observed such in the heat of summer or the cold of winter. That you would precondition your pack, begin driving, and see your car then go back into restricted regen is something I find both surprising and interesting. I would not have thought that was at all likely.

Pack heating and pack cooling thresholds have changed a bit over time with different software releases. But what I typically see when it is cold is that preconditioning (the cabin) will also trigger pack heating. That pack heating ceases between about 6C/43F and 11C/53F

My most recent example was a few days ago. Overnight ambient temps were down to about -11C/12F (my car is parked outside). My cold-soaked pack the next morning measured -1.6C/29F. I turned on Climate - which triggers pack heating if the pack is below the threshold. The car displayed both the blue snowflake (reduced battery capacity) and orange "bacon strips" (battery heating).

The orange "bacon strips" disappeared, and pack heating stopped, after 25-27 minutes, at which point the pack temp was 11.6C/53F.

To answer your original question, no, it would not be a good idea to heat the pack to arriving-at-the-Supercharger levels (~49C/120F). Such temperatures are necessary when DC Fast Charging to obtain decent charge rates, but such heat levels are actually quite detrimental to battery health in the long term. It's a little bit like robbing Peter to pay Paul. You need heat to avoid Lithium plating at those elevated charge rates, and for sure the molecular activity in a hot battery is quite robust, but by and large you want to avoid those kind of pack temps.

My own cold-weather protocol boils down to:

• Adding a few percent of charge - I typically charge to 55% most of the year, but I'll bump that to around 62% during the winter - to give a little extra buffer given the lowered range that EV's get in cold weather.
• Precondition the battery pack (turn Climate on) around 30 minutes before using the car, while it is plugged in.
• Charge immediately after returning from a drive, while the pack is warm.

 

[LikesToys]

Our winters here in the mid-Atlantic are certainly much milder than what you see up north. But I've monitored pack temps in many conditions (with SMT) and what I can say is that the only scenario where I have ever observed pack temps declining while driving is following a Supercharger session (where pack temps will peak around 65C/150F, or a bit more), when the car is actively cooling the pack.

Model 3's (and I assume all Tesla's) have negligible pack cooling from airflow while driving. I have not observed such in the heat of summer or the cold of winter. That you would precondition your pack, begin driving, and see your car then go back into restricted regen is something I find both surprising and interesting. I would not have thought that was at all likely.

Pack heating and pack cooling thresholds have changed a bit over time with different software releases. But what I typically see when it is cold is that preconditioning (the cabin) will also trigger pack heating. That pack heating ceases between about 6C/43F and 11C/53F

My most recent example was a few days ago. Overnight ambient temps were down to about -11C/12F (my car is parked outside). My cold-soaked pack the next morning measured -1.6C/29F. I turned on Climate - which triggers pack heating if the pack is below the threshold. The car displayed both the blue snowflake (reduced battery capacity) and orange "bacon strips" (battery heating).

The orange "bacon strips" disappeared, and pack heating stopped, after 25-27 minutes, at which point the pack temp was 11.6C/53F.

To answer your original question, no, it would not be a good idea to heat the pack to arriving-at-the-Supercharger levels (~49C/120F). Such temperatures are necessary when DC Fast Charging to obtain decent charge rates, but such heat levels are actually quite detrimental to battery health in the long term. It's a little bit like robbing Peter to pay Paul. You need heat to avoid Lithium plating at those elevated charge rates, and for sure the molecular activity in a hot battery is quite robust, but by and large you want to avoid those kind of pack temps.

My own cold-weather protocol boils down to:

• Adding a few percent of charge - I typically charge to 55% most of the year, but I'll bump that to around 62% during the winter - to give a little extra buffer given the lowered range that EV's get in cold weather.
• Precondition the battery pack (turn Climate on) around 30 minutes before using the car, while it is plugged in.
• Charge immediately after returning from a drive, while the pack is warm.

I really think you have hit the nail on the head regarding you cold-weather protocol - I plan to do same.

 

[LikesToys]

My sense is that the manufacturer has tested the Battery Management System, developed an approach that works well for most situations, therefore it may be risky to force the car to function outside of its pre-programmed BMS. You might be doing some expensive damage over the long term. I do think that if you can get away with a lower state of charge it may increase battery longevity but in the end just preheat the car as Regaj has suggested.

 

[MOE J]

APP-should have JUST BATTERY WARMER, the preconditioning warms the steering wheel, ALL the seats, defrosts front and back window, then the battery warmer.

The vehicle should just heat the battery by itself when temps go below freezing, for like 5-10 minutes a few hours before departure. Just enough for REGEN BRAKING to function properly.

 

[LikesToys]

As a new owner MY LR (as of Sat) I am actually in the process of reading the manual. I was surprised to find that in Chill mode, the car moves heat from the battery to the cabin if required (which I new) but that in Standard mode it does not - instead it heats the battery to a higher level so that the battery can provide more power to acceleration if needed.

Here is the exact wording from the manual:
Chill / standard mode

You can improve the efficiency of the cabin heating by reducing your selected acceleration mode. This allows the heat pump system to take more heat from the Battery to efficiently heat the cabin, instead of maintaining the Battery's ability to provide peak acceleration performance. This helps to maximize driving efficiency in colder weather. Note that when subsequently increasing the acceleration mode, the Battery requires time to warm up before the increased level of acceleration is available.

 

[GtiMart]

The car moves heat from the battery to the cabin in all modes, as long as there's enough heat in the battery, but it might do it more (e.g. allow a lower battery temp) in chill mode as you don't need full acceleration power. The car does not actively heat (e.g. generate additional heat expressely for) the battery when you start driving unless you navigate to a supercharger.
Tesla engineers seem to believe that a battery around 10-11C is plenty efficient and provides most of the regen so they don't waste additional energy heating it further when you condition the cabin before departure. At that temperature you don't "lose energy because the battery is cold", the snowflake doesn't appear. Remember that batteries don't like to be too warm for their longevity. The BMS will only heat them to 40-50C if you need to precondition for supercharging, and that is only to allow fast charging without damaging the battery. As soon as you're done charging the car cools the battery down again.

The BMS will manage the battery health, you don't have to worry about that unless you park in -30C for more than 24h as the manual states. In that situation you might want to charge a little bit so the car heats the battery. If you need the range, charge and condition the cabin before you leave. That's all there is to it. You can enable the option to blend friction brakes when regen isn't preset so you won't even feel it.

 

[tga]

APP-should have JUST BATTERY WARMER, the preconditioning warms the steering wheel, ALL the seats, defrosts front and back window, then the battery warmer.

The vehicle should just heat the battery by itself when temps go below freezing, for like 5-10 minutes a few hours before departure. Just enough for REGEN BRAKING to function properly.

Or just turn on "Apply brakes when regenerative braking is limited" (pedals & steering menu) and don't worry about it.

You really want to use the friction brakes periodically anyway. It will scuff off surface rust and prevent build up that can lead to permanent rust pitting on the rotors, brake pedal pulsing, decreased braking effectiveness, reduced safety, blah, blah, blah. Especially in northern winters when the rotors get hit with salt spray.

I've had to replace rusty rotors that were otherwise fine (plenty of thickness, runout w/in spec, etc) on a few vehicles (including my S at 120k miles).

 

[MOE J]

I’ve been using the NAVIGATE TO SUPER CHARGER then just driving to work, seems to help.

 

[GtiMart]

You are forcing your car to heat the battery to 45-50C (if you drive long enough to reach that) which is not great for battery longevity, unless you need to charge it fast, and only for a short time. As soon as you deactivate that, the car will then work hard to cool the battery, spending another good chunk of energy.
Conditioning the cabin before leaving will heat the battery to around 10C, plenty enough to get regen and good efficiency without being detrimental to your battery health.

 

[tga]

You are forcing your car to heat the battery to 45-50C (if you drive long enough to reach that) which is not great for battery longevity, unless you need to charge it fast, and only for a short time. As soon as you deactivate that, the car will then work hard to cool the battery, spending another good chunk of energy.
Conditioning the cabin before leaving will heat the battery to around 10C, plenty enough to get regen and good efficiency without being detrimental to your battery health.

And wasting plenty of electrons in the process.

As I have said elsewhere, it is absolutely not necessary to pre-condition the battery for normal driving. The car will limit discharge/charge (acceleration/regen) as needed to protect the battery. Pre-condition as needed for your comfort. Don't worry about the battery. The car will take care of it automatically.

 

[MOE J]

Hmmm ok

 

[Justjim]

Our winters here in the mid-Atlantic are certainly much milder than what you see up north. But I've monitored pack temps in many conditions (with SMT) and what I can say is that the only scenario where I have ever observed pack temps declining while driving is following a Supercharger session (where pack temps will peak around 65C/150F, or a bit more), when the car is actively cooling the pack.

Model 3's (and I assume all Tesla's) have negligible pack cooling from airflow while driving. I have not observed such in the heat of summer or the cold of winter. That you would precondition your pack, begin driving, and see your car then go back into restricted regen is something I find both surprising and interesting. I would not have thought that was at all likely.

Pack heating and pack cooling thresholds have changed a bit over time with different software releases. But what I typically see when it is cold is that preconditioning (the cabin) will also trigger pack heating. That pack heating ceases between about 6C/43F and 11C/53F

My most recent example was a few days ago. Overnight ambient temps were down to about -11C/12F (my car is parked outside). My cold-soaked pack the next morning measured -1.6C/29F. I turned on Climate - which triggers pack heating if the pack is below the threshold. The car displayed both the blue snowflake (reduced battery capacity) and orange "bacon strips" (battery heating).

The orange "bacon strips" disappeared, and pack heating stopped, after 25-27 minutes, at which point the pack temp was 11.6C/53F.

To answer your original question, no, it would not be a good idea to heat the pack to arriving-at-the-Supercharger levels (~49C/120F). Such temperatures are necessary when DC Fast Charging to obtain decent charge rates, but such heat levels are actually quite detrimental to battery health in the long term. It's a little bit like robbing Peter to pay Paul. You need heat to avoid Lithium plating at those elevated charge rates, and for sure the molecular activity in a hot battery is quite robust, but by and large you want to avoid those kind of pack temps.

My own cold-weather protocol boils down to:

• Adding a few percent of charge - I typically charge to 55% most of the year, but I'll bump that to around 62% during the winter - to give a little extra buffer given the lowered range that EV's get in cold weather.
• Precondition the battery pack (turn Climate on) around 30 minutes before using the car, while it is plugged in.
• Charge immediately after returning from a drive, while the pack is warm.

I condition the cabin for about 10-15 minutes before leaving and the cabin is upwards of 20C on a -10C day. 2016 X. Is there a battery temperature somewhere? Probably a dumb Q.

 

[Regaj]

I condition the cabin for about 10-15 minutes before leaving and the cabin is upwards of 20C on a -10C day. 2016 X. Is there a battery temperature somewhere? Probably a dumb Q.

Not a dumb question at all. Tesla's capture a ton of real-time data at a very granular level. Things like temp and voltage of every single cell in the battery pack. Alas, outside of a very narrow use case involving Ludicrous mode, I'm not aware of any OEM way to view pack temp.

A bluetooth ODBII reader and the Scan My Tesla app fixes that... and will give you access to most of what the car is reporting.

 

[Justjim]

Not a dumb question at all. Tesla's capture a ton of real-time data at a very granular level. Things like temp and voltage of every single cell in the battery pack. Alas, outside of a very narrow use case involving Ludicrous mode, I'm not aware of any OEM way to view pack temp.

A bluetooth ODBII reader and the Scan My Tesla app fixes that... and will give you access to most of what the car is reporting.

Hmmm. ODBII sounds like an Amazon gadget.
You sound like you know batteries...
Every time I go into tesla service or the mall sales, I ask about range. I have a 2016 X 90D. On a 100% charge to go Toronto to London, Ontario which is about 200km. I'll drive 110 to 130kph. I'll have about 30% left when I get there. Worst was a 70kph head wind and 20% there and 35% coming back.
The recent service guy told me to take the battery down to 5-10% and trickle charge, slower the better, so I plugged into 120V outlet (115V actual) and it took 2 1/2 days to get it to 97%. It wouldn't go to 100%. He said it would do something to the cells to ensure they were all up to optimum... I'm now down to about 40% and going to go to a supercharger for a trip on Monday. I'll go to 90%. I can usually go to Hamilton (100km) and back with 90% and supercharge when almost home.
Does his suggestion to trickle charge make any sense, or was it another way to make me go away?

 

[Justjim]

Or just turn on "Apply brakes when regenerative braking is limited" (pedals & steering menu) and don't worry about it.

You really want to use the friction brakes periodically anyway. It will scuff off surface rust and prevent build up that can lead to permanent rust pitting on the rotors, brake pedal pulsing, decreased braking effectiveness, reduced safety, blah, blah, blah. Especially in northern winters when the rotors get hit with salt spray.

I've had to replace rusty rotors that were otherwise fine (plenty of thickness, runout w/in spec, etc) on a few vehicles (including my S at 120k miles).

It's a good practice to apply your breaks while coasting before parking when it is raining. It will warm the rotors and pads to dry them to minimize the rusting between the two. If you've ever seen a rotor with the wheel off, you'll see the outline of the pad on the rotor where it has sat, wet.

 

[Regaj]

Hmmm. ODBII sounds like an Amazon gadget.

There are a couple things you need, in addition to the software, if you want to see all the data the car is reporting. If you decide to explore that rabbit hole, the web site here will get you started: scan my tesla

Does his suggestion to trickle charge make any sense, or was it another way to make me go away?

There are countless posts, here and elsewhere, regarding attempts to improve or restore lost range. A lot of people believe in that kind of stuff.

Personally, I think the service fellow who suggested you do a long trickle charge was mistaken, to put it kindly. Certainly wouldn't hurt anything. But not helpful, either.

The best that might be achieved with the various charging stratagems is to, maybe, slightly improve BMS accuracy by giving it some extra data points to calculate from.

There are a number of practices that an owner can apply to minimize and slow battery degradation. But once degradation has occurred, there's no climbing back up that curve to get it back.

 

[Justjim]

There are a couple things you need, in addition to the software, if you want to see all the data the car is reporting. If you decide to explore that rabbit hole, the web site here will get you started: scan my tesla



There are countless posts, here and elsewhere, regarding attempts to improve or restore lost range. A lot of people believe in that kind of stuff.

Personally, I think the service fellow who suggested you do a long trickle charge was mistaken, to put it kindly. Certainly wouldn't hurt anything. But not helpful, either.

The best that might be achieved with the various charging stratagems is to, maybe, slightly improve BMS accuracy by giving it some extra data points to calculate from.

There are a number of practices that an owner can apply to minimize and slow battery degradation. But once degradation has occurred, there's no climbing back up that curve to get it back.

Sigh.... I've also been told that the service screen has a mechanism to discharge the battery and recharge to determine the % of deterioration. I think warranty must maintain 75% of original....also told that Tesla will perform this test if requested (at what cost!?). I'm afraid of Tesla. I've gone in with a $54 estimate and crawled away with a $1500 bill. Another with a low estimate for a $900 fuse.