Cold Weather Charging: what really happened with MS not charging?

Jhodgesatmb

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In heating the cabin from -20°F (!!?!) the PTC heater took an early lead but was surpassed by the Heat Pump, which got to 60°F in 30 minutes. The PTC was struggling to get there at 40 minutes, but by then the Heat Pump cabin was pushing 80°F.
You forgot to mention that the heat pump was only pushing 10 degrees Fahrenheit after 20 minutes, so they were recommending a 20-minute preheat for everyone. If you review the charging video they made last week then you also know that it took much longer to warm the battery to a point where it could begin charging on a DC fast charger. I do not know if these tests could be run in parallel (namely, the 45 minutes to start the charge and the 20 minutes to start warming the cabin) but I wish they had done a combined test.
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Ogre

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I watch a lot of their videos these days. They seem manufacturer agnostic and put the cars through their paces, and chargers, etc. I am driving our Model Y to Denver next month and found the OutOfSpec videos very helpful. I am so glad that I have a Tesla. All the people that rely on the other brand chargers are so screwed, and they have good reason to be upset.
They read their favorite auto site which assures them their __insert advertiser name__ is just as good as a Tesla and everything is fine.
 

Bill906

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If something went wrong in the inverter control, the vehicle cannot move. Like, it needs to make specific phased signals and amperage to drive the motors
Depends on what goes wrong. There are failure modes the can cause unintended motion.

For example, there are many different motor control modes inverters use. A common way, and the way I expect Tesla uses to control PM motors requires the inverter control to know the exact position of the rotor, with respect to the stator. This is done with a feedback device, most likely a device called an encoder. The encoder is mechanically connected to the motor shaft, and sends electical signals to the inverter controller telling it the angle of the rotor. If that information is wrong, due to damage, disconnection, slippage etc, the control would be erratic. Depending on what is wrong with the data, it could cause the motor rotation to turn opposite of intended. Let’s say the motor is supposed to be stopped but moves a fraction of a degree in the forward direction. The inverter control compensates by applying slight negative torque. Because of the encoder feedback issue, the commanded negative torque actually creates positive torque moving motor more forward, creating a run away condition. This failure mode is rare, but not impossible.

The control has both the input from the motor to know what signal it's creating and from how much the wheel is rotating
Not sure what “input from the motor” would be. Often the encoder (explained above) is built into a motor. I would consider that input from the encoder but would understand someone referring to it as input from the motor. Semantics.

If I recall, though, a Tesla is programmed to cut power to the motor when you press on the brake pedal, as well.
If car was slowing down due to regeneration, and stepping on the brake cut power to the motor, the car would no longer be able to regenerate and would not decelerate at the same rate, not until enough brake pressure was applied that was equal to or greater than the stopping power the regen was creating.

Also, if you were sitting in the car waiting for it to warm up and you kept your foot on the brake pedal, would this not allow power to the motor for heating purposes?

This would be true if a mechanic were to work on it. Not if someone is to walk past it, or in the control room, or to grab a part as it goes past them
Depends on the conveyor belt and how it was guarded. If someone is in a place where conveyor movement could hurt them, it would not be considered safe to rely just on the control systems ability to hold zero speed. In that scenario, you would typically expect the connection between motor and inverter to be disconnected. Not powered but told not to move.

My background in using motor/inverter systems in the industrial world may be skewed from what is in a car because in my world, the system is not a matched set. The inverter I use is designed to work with many different motors, and can be programmed to use different control methods, sensors etc. The same inverter (Variable Frequency Drive, or VFD) used on a PM motor to run an Air Conditioning compressor on the roof of a hospital, is the same VFD used to power an induction motor in a paper mill used to turn a roll on the paper machine, or the same VFD used to control the pumps that feed municipal water to your kitchen tap. Each system is unique in the motor, control method, sensors and safety level used.
 

HaulingAss

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I’ve seen complaints about being unable to charge in the cold, but only when using the 120v charging. Most of that 4kw went into warming the pack.

The 100kw+ from DCFC should be able to melt your face in sub-zero temperatures, and is certainly enough to get charging.

I guess I’m a little disappointed that a thermal malfunction serious enough to prevent cold-weather charging was not detected sooner. Battery temp is critical to longevity and is closely monitored. Maybe an OTA fix?
If you have a Tesla, you should use the navigation system to let the car know you are planning to Supercharge about 45 minutes before you get there. The car will use waste heat from various components (including the main computer CPU which is liquid cooled) to heat your battery before you arrive at the Supercharger so you can start charging as soon as you arrive. If it was arctic cold, I would enter the Supercharger into the nav system as a destination when I was 100 miles out.

I've never had an issue charging in the cold in over 4 years with two Tesla unless trying to charge at below 20 degrees F with a 120v outlet. In that case it took a number of hours for the battery to get warm enough to start charging. This is why I recommend a 240V 30 amp outlet at home as a good minimum. This would not be necessary if you lived on Molokai or Lanai in Hawaii because the islands are so small and weather so mild, 120V would have you constantly topped up!
 

Crissa

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C'mon, you gotta have had conveyor sushi, at least. It doesn't stop in the presence of humans. If the car had to disconnect power every time humans were near, it would never be able to drive around town.

It's okay, we all make little mistakes like that.

And yeah, it's possible for a broken encoder to make the drive motor run backwards. Hence also pointing out all the other sensors in a Tesla.

-Crissa
 


ÆCIII

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I had no issues charging at -2 degrees, and I had no heat pump or octo-valve in my Tesla. The charger was only about 3 miles from me so it charged fine even without much time warming up. Of course I do agree that's its probably not wise for someone to leave a Tesla at a supercharger frozen for all night or two nights, and then attempting to charge it without any driving at all. Not sure if this is what happened with their malfunction or not.

I'm not sure of all the exact details this thread is about, but one might ask how many ICE cars had trouble starting at minus 2 degrees this past week, and needed an extra 12 volt charge of their own? I personally heard two people discussing how their car wouldn't start last Friday morning. The inconvenient reality is that most ICE cars need an electric motor running first to even start.

Then there's the sheer number of Teslas and EVs in Norway where it's freezing for months at at time much colder then this little 'freeze' the U.S. just had. As an early country for high EV adoption for years already by now, Norway has many Teslas and EVs with or without the heat pump or octo-valves. If there were any serious problem trends unmanageable in cold weather, we certainly would've heard more of it from Norway owners by now.

I think most intelligent people realize by now that with the number of Teslas on the road (and increasing), the haters are going to try and shout from the roof tops if even one of them has any kind of glitch or even the slightest malfunction. IMO they're really just showing how desperate they are.

- ÆCIII
 
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HaulingAss

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I had no issues charging at -2 degrees, and I had no heat pump or octo-valve in my Tesla. The charger was only about 3 miles from me so it charged fine even without much time warming up. Of course I do agree that's its probably not wise for someone to leave a Tesla at a supercharger frozen for all night or two nights, and then attempting to charge it without any driving at all. Not sure if this is what happened with their malfunction or not.

I'm not sure of all the exact details this thread is about, but one might ask how many ICE cars had trouble starting at minus 2 degrees this past week, and needed an extra 12 volt charge of their own? I personally heard two people discussing how their car wouldn't start last Friday morning. The inconvenient reality is that most ICE cars need an electric motor running first to even start.

Then there's the sheer number of Teslas and EVs in Norway where it's freezing for months at at time much colder then this little 'freeze' the U.S. thinks it got. As a early country for high EV adoptions for years already by now, Norway has many of the Teslas and EVs without the heat pump or octo-valves. If there were any serious problem trends unmanageable in cold weather, we certainly would've heard more of it from Norway owners by now.

I think most intelligent people realize by now that with the number of Teslas on the road (and increasing), the haters are going to try and shout from the roof tops if even one of them has any kind of glitch or even the slightest malfunction. IMO they're really just showing how desperate they are.

- ÆCIII
Well put!

It's getting to the point when you can tell the people who have no EV experience from those who do simply by their comments about how EV's fare in cold weather. Anyone who says Tesla's don't work well in cold weather have never used a Tesla in cold weather. Yes, you lose some efficiency but no EV owner I know thinks that's a problem. It would be like saying "ICE cars don't run well on gasoline because they have an efficiency below 30%."

Oh, wait...that's actually true! :ROFLMAO:
 

ldjessee

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My Leaf was not happy that Friday at -9 (-31 windchill), but all did was drive it into the garage, it still would not go over 5 mph… the ‘turtle’ mode.
Glad it had 60% charge when it got cold. It has had several days to ‘warm’ up in our garage that is usually above 40 even if the temp outside is below freezing (but not below zero).
 

Ogre

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My Leaf was not happy that Friday at -9 (-31 windchill), but all did was drive it into the garage, it still would not go over 5 mph… the ‘turtle’ mode.
Glad it had 60% charge when it got cold. It has had several days to ‘warm’ up in our garage that is usually above 40 even if the temp outside is below freezing (but not below zero).
I guess that decision to not have an active heat management system for the batteries doesn’t play out so good all around.

Same choice that makes it so you can’t “Fast” charge it twice in the same day makes it so you can’t drive it on a cold day.
 

ldjessee

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I guess that decision to not have an active heat management system for the batteries doesn’t play out so good all around.

Same choice that makes it so you can’t “Fast” charge it twice in the same day makes it so you can’t drive it on a cold day.
Yes, the Leaf is POS for long travel. People have done it, but it is an 'adventure'...

It does what we need it right now, which is an errands/local travel car.
 


Ogre

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Yes, the Leaf is POS for long travel. People have done it, but it is an 'adventure'...

It does what we need it right now, which is an errands/local travel car.


Wasn’t trying to pan the Leaf. For a 5+ year old EV, it’s not bad. Teslas from then were better, but much more expensive. My brother has one as does one of my wife’s friends and they love it.

But they end every trip in their driveway.
 

Crissa

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Yes, the Leaf is POS for long travel. People have done it, but it is an 'adventure'...

It does what we need it right now, which is an errands/local travel car.
The tires on my car currently were lent to a Leaf a couple times and it went from the Bay here to BC and back - in the snow. ^-^

I think this is the last year I'll use these tires, but they don't seem to be aging hardly at all. I only drive a few thousand miles on them per year, and they're stored at 50F in the dark in semi-air-tight containers the rest of the year.

-Crissa
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