Simple Question. Better to Charge to 80% or 90%

[jerry33]

Thanks.

So, it sounds like as long as it’s plugged in, the car will keep the battery safe from damage from the cold by keeping it warm.

If not plugged in, don’t leave it in those cold temps for long.

Is this correct.

Even when plugged in, don't leave it in -30 conditions for 24 hours is my understanding.

 

[M109Rider]

Even when plugged in, don't leave it in -30 conditions for 24 hours is my understanding.

Okay, that’s what I was afraid of.
I’ll need to heat my garage for those nasty bouts of weather I guess.

Thanks

 

[jamnmon66]

Assuming the Model 3 is the same as the Model S, you are not supposed to leave it in -30 C or below for more than 24 hours (The ambient temperature is -30 or lower for 24 hours continually). It will keep warm if plugged into a 240 V line above -30. A 120 V line will use all it's energy to keep the battery warm and won't actually charge.

Do you have a primary source for this? I don't dispute it but that's the first I've heard of it.

 

[jerry33]

Do you have a primary source for this? I don't dispute it but that's the first I've heard of it.

Fair question. The warranty text from owner warranty manual:

Battery Limited Warranty
The Model S lithium-ion battery (the “Battery”) is an extremely sophisticated powertrain
component designed to withstand extreme driving conditions. You can rest easy knowing that
Tesla’s state-of-the-art Battery is backed by this Battery Limited Warranty, which covers the repair
or replacement of any malfunctioning or defective Battery, subject to the limitations described
below. If your Battery requires warranty service, Tesla will repair the unit, or replace it with a factory
reconditioned unit that has an energy capacity at least equal to that of the original Battery before
the failure occurred. Your vehicle’s Battery is covered under this Battery Limited Warranty for a
period of 8 years or for the number of miles/km specified below for your Battery configuration,
whichever comes first:
• 60 kWh - 125,000 miles (200,000 km)
• 85 kWh - unlimited miles/km
Despite the breadth of this warranty, damage resulting from intentional abuse (including
intentionally ignoring active vehicle warnings), a collision or accident, or the servicing or opening of
the Battery by non-Tesla personnel, is not covered under this Battery Limited Warranty.
In addition, damage resulting from the following activities are not covered under this Battery
Limited Warranty:
• Exposing the vehicle to ambient temperatures above 140°F (60°C) or below -22°F (-30°C) for
more than 24 hours at a time;
• Physically damaging the Battery, or intentionally attempting, either by physical means,
programming, or other methods, to extend (other than as specified in your owner
documentation) or reduce the life of the Battery;
• Exposing the Battery to direct flame; or,
• Flooding of the Battery.
The Battery, like all lithium-ion batteries, will experience gradual energy or power loss with time and
use. Loss of Battery energy or power over time or due to or resulting from Battery usage, is NOT
covered under this Battery Limited Warranty. See your owner documentation for important
information on how to maximize the life and capacity of the Battery

 

[arg]

Do you have a primary source for this? I don't dispute it but that's the first I've heard of it.

Which bit? The basic info about -30C is in the Model 3 Owners Manual:

Do not expose Model 3 to ambient
temperatures above 140° F (60° C) or
below -22° F (-30° C) for more than 24
hours at a time.

That text is identical in Model S/Model 3 manuals.

There have been claims about the car running the battery heater if below those temps, but I don't have a primary source or personal experience.

But does @M109Rider really have sustained temperatures below -30 inside his garage? Being inside a garage is much better than outside even if the temperature is the same, because wind can cool the exposed underside of the battery pack. The battery has substantial thermal mass, so in still air you'd need quite a long time of exposure to the low temperature to actually get the inside of the pack down to that level (which is probably behind Tesla's 24-hour recommendation). Hence you need average daily temperature below -30 to be a problem, not just the overnight low.

 

[brkaus]

But does @M109Rider really have sustained temperatures below -30 inside his garage? Being inside a garage is much better than outside even if the temperature is the same, because wind can cool the exposed underside of the battery pack. The battery has substantial thermal mass, so in still air you'd need quite a long time of exposure to the low temperature to actually get the inside of the pack down to that level (which is probably behind Tesla's 24-hour recommendation). Hence you need average daily temperature below -30 to be a problem, not just the overnight low.

This was my question as well. I would expect garage to be somewhat higher temp.

 

[jerry33]

But does @M109Rider really have sustained temperatures below -30 inside his garage? Being inside a garage is much better than outside even if the temperature is the same, because wind can cool the exposed underside of the battery pack. The battery has substantial thermal mass, so in still air you'd need quite a long time of exposure to the low temperature to actually get the inside of the pack down to that level (which is probably behind Tesla's 24-hour recommendation). Hence you need average daily temperature below -30 to be a problem, not just the overnight low.

Right, it's all 24 hours, not just the lows. However, if you live in Winnipeg or Grand Prairie, AB or some similar location, -40 is not uncommon with a high of -30 or less, so an unheated garage in those areas would subject the car to those temperatures.

I've found the battery cools quite quickly due to the aluminum casing. I've had it give a "too cold" message when running at low speeds in cold weather (although quite a bit warmer than -30).

 

[jamnmon66]

Fair question. The warranty text from owner warranty manual:

Battery Limited Warranty
The Model S lithium-ion battery (the “Battery”) is an extremely sophisticated powertrain
component designed to withstand extreme driving conditions. You can rest easy knowing that
Tesla’s state-of-the-art Battery is backed by this Battery Limited Warranty, which covers the repair
or replacement of any malfunctioning or defective Battery, subject to the limitations described
below. If your Battery requires warranty service, Tesla will repair the unit, or replace it with a factory
reconditioned unit that has an energy capacity at least equal to that of the original Battery before
the failure occurred. Your vehicle’s Battery is covered under this Battery Limited Warranty for a
period of 8 years or for the number of miles/km specified below for your Battery configuration,
whichever comes first:
• 60 kWh - 125,000 miles (200,000 km)
• 85 kWh - unlimited miles/km
Despite the breadth of this warranty, damage resulting from intentional abuse (including
intentionally ignoring active vehicle warnings), a collision or accident, or the servicing or opening of
the Battery by non-Tesla personnel, is not covered under this Battery Limited Warranty.
In addition, damage resulting from the following activities are not covered under this Battery
Limited Warranty:
• Exposing the vehicle to ambient temperatures above 140°F (60°C) or below -22°F (-30°C) for
more than 24 hours at a time;
• Physically damaging the Battery, or intentionally attempting, either by physical means,
programming, or other methods, to extend (other than as specified in your owner
documentation) or reduce the life of the Battery;
• Exposing the Battery to direct flame; or,
• Flooding of the Battery.
The Battery, like all lithium-ion batteries, will experience gradual energy or power loss with time and
use. Loss of Battery energy or power over time or due to or resulting from Battery usage, is NOT
covered under this Battery Limited Warranty. See your owner documentation for important
information on how to maximize the life and capacity of the Battery

Which bit? The basic info about -30C is in the Model 3 Owners Manual:

Do not expose Model 3 to ambient
temperatures above 140° F (60° C) or
below -22° F (-30° C) for more than 24
hours at a time.

That text is identical in Model S/Model 3 manuals.

There have been claims about the car running the battery heater if below those temps, but I don't have a primary source or personal experience.

But does @M109Rider really have sustained temperatures below -30 inside his garage? Being inside a garage is much better than outside even if the temperature is the same, because wind can cool the exposed underside of the battery pack. The battery has substantial thermal mass, so in still air you'd need quite a long time of exposure to the low temperature to actually get the inside of the pack down to that level (which is probably behind Tesla's 24-hour recommendation). Hence you need average daily temperature below -30 to be a problem, not just the overnight low.

Cool. Thanks. Good to know. Is that the same on the 3?

 

[arg]

Which bit? The basic info about -30C is in the Model 3 Owners Manual:

Do not expose Model 3 to ambient
temperatures above 140° F (60° C) or
below -22° F (-30° C) for more than 24
hours at a time.

 

[jamnmon66]

LOL. Right there in my reply. Thanks.

I wonder if the electrolyte freezes/crystallizes or something. I don't remember it ever getting below - 10F in the Denver area so it's probably never going to be an issue for me but I'm just curious.

 

[M109Rider]

Which bit? The basic info about -30C is in the Model 3 Owners Manual:

Do not expose Model 3 to ambient
temperatures above 140° F (60° C) or
below -22° F (-30° C) for more than 24
hours at a time.

That text is identical in Model S/Model 3 manuals.

There have been claims about the car running the battery heater if below those temps, but I don't have a primary source or personal experience.

But does @M109Rider really have sustained temperatures below -30 inside his garage? Being inside a garage is much better than outside even if the temperature is the same, because wind can cool the exposed underside of the battery pack. The battery has substantial thermal mass, so in still air you'd need quite a long time of exposure to the low temperature to actually get the inside of the pack down to that level (which is probably behind Tesla's 24-hour recommendation). Hence you need average daily temperature below -30 to be a problem, not just the overnight low.

Thanks.
My garage would definitely be warmer than outside temps. Maybe by 5 or 10 degrees at the most.
So if the car doesn’t self heat in those temps, I would add heat to the garage to get it out of risk. For the 4 a 8 weeks a year this is a problem, is not too bad to manage.

Just wanted to know if the car would take care of it on its own.

Thanks again.

 

[timk225]

Compromise with your indecisive self. 85%

NO!!! 83% is the way to go!!!

 

[Shock-On-T]

Just charge at 90% and don't worry about it. I did charge at 80% for a couple of years, but noticed that the displayed range went down. Went back up after charging to 90%, with the odd 100% charge on trips, so the loss appears to be balance (on the 85S, balancing starts at 93%). After 108K miles and over five years it's now lost between 3% and 4%. Note that driving under 50% heats the battery more than driving above 50% for the same amount of power required, so charging to 50% isn't the answer unless the car is being stored.

Also the loss can be caused by the range estimation algorithm getting confused after long periods of not exploring the “edges” of its domain.
In other words, it’s not really physically lost, just the car starts to underestimate. Once you do a few full charges and discharges the algorithm gets a better idea of the true range.

 

[timk225]

Correct me if I'm wrong, but I thought the 3 battery didn't have a heater in it like the S and X?

 

[brkaus]

Thanks.
My garage would definitely be warmer than outside temps. Maybe by 5 or 10 degrees at the most.
So if the car doesn’t self heat in those temps, I would add heat to the garage to get it out of risk. For the 4 a 8 weeks a year this is a problem, is not too bad to manage.

Just wanted to know if the car would take care of it on its own.

Thanks again.

I believe it will try to take care of its own. There may be a limit as to how much heat it can put into the system vs the loss rate.

I would do as you suggest and add a little heat to keep it safe.

Correct me if I'm wrong, but I thought the 3 battery didn't have a heater in it like the S and X?

It somehow uses the inverter/motor to generate heat into the loop is my understanding.

 

[dhrivnak]

Two factors I do not see discussed here that were/are very important for the Roadster batteries. First unless one charged to 83% or more the bricks were not balanced. If you only charged a Roadster to 70% the batteries would become unbalanced and you WOULD lose range. The second is we occasionally needed to drive from close to 100 to close to 0 for the computer to calculate the true range of the battery. Unless we occasionally did a long drive the mileage estimates would drift off.

It really would be nice for a Tesla Battery Engineer to weigh in.

 

[brkaus]

Two factors I do not see discussed here that were/are very important for the Roadster batteries. First unless one charged to 83% or more the bricks were not balanced. If you only charged a Roadster to 70% the batteries would become unbalanced and you WOULD lose range. The second is we occasionally needed to drive from close to 100 to close to 0 for the computer to calculate the true range of the battery. Unless we occasionally did a long drive the mileage estimates would drift off.

It really would be nice for a Tesla Battery Engineer to weigh in.

93% is the point that triggers balancing on an S/X from what I have read here.

 

[Snowstorm]

In Ontario, even in the north, I would not worry about -30C for 24 hours at a time. Yes, the nighttime low may hit -30, but I would be hard pressed to find any day in he past 30 year where I have understanding of what temperature it is when the entire day is below -30. If you are inside a garage, you are double fine.

 

[goto10]

Correct me if I'm wrong, but I thought the 3 battery didn't have a heater in it like the S and X?

It doesn't have a discrete heating component. Heat is generated in the motor and coolant is pumped through the motor to the battery to warm it. They are able to do this even without causing the motor to turn.

 

[arg]

I wonder if the electrolyte freezes/crystallizes or something.

I believe that's the issue behind Tesla's -30C warning.

Lithium batteries quite like being cold if just sat on the shelf neither charging nor discharging, but mustn't go below the electrolyte freezing point. Charging is the most sensitive, since charging below the minimum temperature (about 0C) causes disasterous damage to the cells; the car of course takes care of this using the battery heater (virtual battery heater via the motor in M3), though of course takes much longer as it has to heat the battery before charging can start. Discharge is inefficient at low temperatures, but not particularly harmful unless done at high rates.

So, there's little point in heating the garage unless there's a serious prospect of going below -30 for a while AND you aren't using/charging the car.

If you are using/charging the car, then it will be (slightly) heating the garage anyhow - it arrives warmer than ambient after a drive, and any charging will explicitly heat the battery. In fact it will be heating the garage a tiny amount even if unused - the 'vampire drain' to run the computers/keyless-entry/comms amounts to about 50W in a Model S, though reportedly rather less on a M3.