Cold Temperature Battery Maintenance

[edgecrusher]

Did a bunch of searching, reading, and didn't quite find an answer to this one.

If I am parked outside in well below freezing weather for extended periods (eg. 3-4 days), plugged in - does the battery management system maintain the battery temperature to be 10 deg C (or warm), or does it just let it freeze and then heat it up based on whenever you start pre-conditioning or charging?

In this scenario - best to first set it to ~60%, then bump it up to 80% the day before planning on driving and pre-condition/departure charge, etc?

 

[jcanoe]

The Tesla Model Y's battery management system will not use energy to warm the battery unless A) charging, B) preconditioning in cold temperatures, C) while driving.

The only caveat Tesla provides is to not let the Tesla vehicle be exposed to very high or very low temperatures for more than 24 hours; very low being -23F (-30C)

For maximum efficiency in winter temperatures you would want to complete charging shortly before preconditioning and driving. The battery will already be warmed from charging and the heat pump will be able to use the warm coolant from the battery to warm the passenger cabin.

 

[edgecrusher]

The Tesla Model Y's battery management system will not use energy to warm the battery unless A) charging, B) preconditioning in cold temperatures, C) while driving.

The only caveat Tesla provides is to not let the Tesla vehicle be exposed to very high or very low temperatures for more than 24 hours; very low being -23F (-30C)

For maximum efficiency in winter temperatures you would want to complete charging shortly before preconditioning and driving. The battery will already be warmed from charging and the heat pump will be able to use the warm coolant from the battery to warm the passenger cabin.

So ‘if’ it’s going to be -30 for a few days…

precondition in the morning and go for a drive to heat it up…

Or

Start charging to a low % and increase it every day or so (to force heating and charging)

Or

Do nothing and precondition before you actually need to drive

 

[jcanoe]

At -30C keep the Tesla vehicle plugged in. You can use Scheduled Departure Preconditioning to warm up the Tesla vehicle at the same time each day even if you don't drive the vehicle. Using the Tesla app you can manually precondition several times during the day.

The latest software enables setting a second Scheduled Departure Preconditioning time for a work location, not sure if this would work for the home location as the in-vehicle Scheduled Departure Preconditioning would have already been programmed for the home location.

For more flexible preconditioning options you would have to use a 3rd party app such as Teslafi, Teslamate, Tezlab, Stats for Tesla, Tessie for iOS, Teslascope. I don't have any experience with the 3rd party apps, I just keep a list for reference.

 

[Big Earl]

So ‘if’ it’s going to be -30 for a few days…

precondition in the morning and go for a drive to heat it up…

Or

Start charging to a low % and increase it every day or so (to force heating and charging)

Or

Do nothing and precondition before you actually need to drive

It should (not saying it will, as I don’t have experience in extended cold like this) automatically heat itself if below -30°C and plugged in.

 

[jcanoe]

It should (not saying it will, as I don’t have experience in extended cold like this) automatically heat itself if below -30°C and plugged in.

One would think that this would be noted in the Tesla Model Y Owner's Manual. The manual does not include any information regarding the Tesla vehicle automatically warming the battery while parked in extreme cold temperatures unless charging or preconditioning.

 

[edgecrusher]

Extended camp mode while plugged in could be interesting. Set it to a low temp inside? Might take some experimenting.

 

[jcanoe]

Extended camp mode while plugged in could be interesting. Set it to a low temp inside? Might take some experimenting.

If you don't care about the energy usage, cost then that might be one option. If you precondition or drive every 8 or so hours that should keep the battery temperature from dropping to where it might be an issue.

Another consideration; a nice warm vehicle is an invitation to unwanted pests. Do small animals even venture out in such temperatures?

 

[Big Earl]

One would think that this would be noted in the Tesla Model Y Owner's Manual. The manual does not include any information regarding the Tesla vehicle automatically warming the battery while parked in extreme cold temperatures unless charging or preconditioning.

It states to not leave the vehicle exposed to those temperatures without it being plugged in, which, to me implies that the car will automatically heat the battery to prevent the electrolyte from freezing.

The manual doesn’t state that regular user intervention is required in extremely cold temperatures. I could be wrong, but what’s the point of plugging it in if it doesn’t do anything?

 

[jcanoe]

It states to not leave the vehicle exposed to those temperatures without it being plugged in, which, to me implies that the car will automatically heat the battery to prevent the electrolyte from freezing.

The manual doesn’t state that regular user intervention is required in extremely cold temperatures. I could be wrong, but what’s the point of plugging it in if it doesn’t do anything?

I could not find the statement to not leave the vehicle exposed to those temperatures without it being plugged in. What the Tesla Model Y Owner's Manuals states, seems to be concerned with, is leaving the Tesla Model Y vehicle unplugged for extended period where the battery may become fully discharged.

Page 154:

Battery Care - Never allow the Battery to fully discharge. Even when
Model Y is not being driven, its Battery discharges very
slowly to power the onboard electronics. The Battery
can discharge at a rate of approximately 1% per day,
though the discharge rate may vary depending on
environmental factors (such as cold weather), vehicle
configuration, and your selected settings on the
touchscreen. Situations can arise in which you must
leave Model Y unplugged for an extended period of time
(for example, at an airport when traveling). In these
situations, keep the 1% in mind to ensure that you leave
the Battery with a sufficient charge level. For example,
over a two week period (14 days), the Battery may
discharge by approximately 14%.
Discharging the Battery to 0% may result in damage to
vehicle components. To protect against a complete
discharge, Model Y enters a low-power consumption
mode when the displayed charge level drops to
approximately 0%. In this mode, the Battery stops
supporting the onboard electronics and auxiliary 12V
battery. Once this low-power consumption mode is
active, immediately plug in Model Y to prevent a jump-
start and 12V battery replacement.

Temperature Limits -

For better long-term performance, avoid exposing
Model Y to ambient temperatures above 140° F (60° C)
or below -22° F (-30° C) for more than 24 hours at a
time.

https://www.tesla.com/sites/default/files/model_y_owners_manual_north_america_en.pdf

 

[Big Earl]

Thanks for posting that. Must be some faulty memory going on on my end.

 

[jcanoe]

GM takes a different approach. GM plug-in vehicles such as the Chevy Volt will maintain the battery pack temperature, whenever the vehicle is plugged in, if the battery pack temperature gets close to 32F (0C.) The battery warming cycle lasts 15 or 20 minutes every couple of hours. This can be either a benefit or a liability depending on your perspective. Battery warming can cost $0.25 per day or more, really adds up over the winter months. If you go away and leave your GM vehicle plugged in it remains ready to drive but you are wasting energy, it costs you money for the vehicle's battery to be kept warm until you are ready to drive. Tesla's approach seems to be more about maximizing efficiency, minimizing energy usage.

 

[edgecrusher]

I’ll report back on my finding over the next few weeks. I get mine right after Christmas and will be parked outside up north through New Years. Plugged in of course. Hopefully some of the teslamate type tools will give me some of the data to understand what is going on.

 

[OxBrew]

...Battery warming can cost $0.25 per day or more, really adds up over the winter months. If you go away and leave your GM vehicle plugged in it remains ready to drive but you are wasting energy, it costs you money for the vehicle's battery to be kept warm until you are ready to drive...


$7.50/ month to keep the battery warm? 2 lattes a month. Not seeing how that really adds up to anything worth worrying about. Cold weather living is more expensive. Heck, $500/ month heating bill, vs $125 in the summer. Noise in the system, can't even reliably break out the difference.

 

[Benito1283]

I've been wondering the same exact thing as the OP and Earl - why so critical to leave it plugged in if it's not actively charging or preconditioning? I think the confusion is warranted:

On Tesla's US website, under Winter Driving Tips > Charging Tips > Stay Plugged In, it states, "We recommend leaving your Tesla plugged in as much as possible when it’s not in use. This uses the charging system, rather than your battery, to retain heat." A little vague as to when it is actually 'retaining heat'.

However! On Tesla's UK website, also under Winter Driving Tips > Cold Weather Tips > Stay Plugged In, it states, "We recommend leaving your Tesla plugged in as much as possible when it’s not in use. Doing so helps the battery stay warm by drawing a small amount of power from the wall."

I don't have any apps to tell me what's happening with the battery or shore power during cold nights, but I usually leave it plugged in just in case the UK's statement is more accurate, and since there isn't any downside to doing so for me.

 

[Sophias_dad]

Battery warming can cost $0.25 per day or more

I bet its triple that, but I'm from an area where 1kwh is $0.28 or so.

 

[jcanoe]

I bet its triple that, but I'm from an area where 1kwh is $0.28 or so.

I believe it could approach $0.75 per day but did not want to overstate the cost. Here in Maryland I observed my 2017 Volt battery being warmed on the coldest days. The Volt was parked in my garage where it rarely was colder than 30F. If I unplugged the charging connector the battery would not be warmed.

 

[LoudMusic]

I wish there was a way to tell the car to maintain the battery temperature while plugged in. I can't imagine it would take much power, and properly maintaining something that expensive is totally worth it.

 

[OxBrew]

I wish there was a way to tell the car to maintain the battery temperature while plugged in. I can't imagine it would take much power, and properly maintaining something that expensive is totally worth it.

I think it does, at least at extreme cold temps?

At 8°F for 2 days, I heard something sounded like a pump kick on randomly a couple times. Car was plugged in and at full charge.

 

[Big Earl]

I wish there was a way to tell the car to maintain the battery temperature while plugged in. I can't imagine it would take much power, and properly maintaining something that expensive is totally worth it.

You could see constant draws of a kilowatt or more doing that in very cold weather, for no benefit as far as I’m aware.

If you find yourself in polar cold where there is risk of freezing the electrolyte, you could keep the battery warm by leaving climate control turned on. To minimize power used by climate, set it to LO with fan speed of 1.