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

Ogre

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Since when is ONE person with car issues a newsworthy item?

What happened? IDGAF.

Lots of people had car trouble on Christmas Eve, with the weather we had, likely thousands of people had car trouble. Stuck cars, cars that wouldn’t start, iced keyholes, just flat snowed in, doors frozen shut. This kind of thing happens every single year in sub zero temps.

My suspicion is the author had a deadline and looked for the stupidest anti-Tesla Christmas story he could find on the internet and ran with it.

If hundreds of Teslas were bricked on Christmas eve? That would be a story. But it didn’t happen. Though dozens of EA chargers failed due to cold… but no media coverage?
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Crissa

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One of the guys over on Transport Evolved left his Leaf plugged in outside and the ice welded the plug to the car. No active thermal there! So a day later he had to use a hair-dryer to free the car.

Non-story, tho it was funny to see a Leaf glittering in ice.

-Crissa
 

Bill906

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Thanks @Crissa !

Watching the first video you posted is the first time I’d heard of the HEAT PUMP motor and inverter ran inefficiently to make heat. That makes more sense to me than the idea others have suggested where the DRIVE motor inverters were making the excess heat. The excess heat created by the drive motor inverter would have to heat up the coolant, then get transferred to the refrigerant and ran through the heat pump before finally making it to the cabin condenser and blown into the cabin. Not that that couldn’t work, I just find it to clumsy. I would think the lag time heating up all that mass before seeing any heat in the cabin would be unacceptable.

In the video below he explains all the different modes of the Model 3. In “Heating mode 3” he says the Tesla turns on low voltage heaters. This is one of the places I’d seen evidence that Model 3’s have resistive heaters.

I’m guessing there is still a resistive heater in the current Tesla HVAC systems, but I will concede there may not be, now that the idea of the heat pump inverter is what is used as a heat creator has been pointed out to me.

 

android04

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Thanks @Crissa !

Watching the first video you posted is the first time I’d heard of the HEAT PUMP motor and inverter ran inefficiently to make heat. That makes more sense to me than the idea others have suggested where the DRIVE motor inverters were making the excess heat. The excess heat created by the drive motor inverter would have to heat up the coolant, then get transferred to the refrigerant and ran through the heat pump before finally making it to the cabin condenser and blown into the cabin. Not that that couldn’t work, I just find it to clumsy. I would think the lag time heating up all that mass before seeing any heat in the cabin would be unacceptable.

In the video below he explains all the different modes of the Model 3. In “Heating mode 3” he says the Tesla turns on low voltage heaters. This is one of the places I’d seen evidence that Model 3’s have resistive heaters.

I’m guessing there is still a resistive heater in the current Tesla HVAC systems, but I will concede there may not be, now that the idea of the heat pump inverter is what is used as a heat creator has been pointed out to me.

The older Model 3s (like mine) did not have a heatpump and have a PTC heater for the cabin only. The way they heated up the battery pack was to run the drive unit in a way that's inefficient in order to heat up the coolant that circulates through the battery. Here's a video from one of the same sources as listed in another post where they show how the Octovalve + heatpump work. This video shows how the Superbottle works in the older cars (before there was an Octovalve + heatpump)

Here's another video that shows CAN bus data from an older Model 3 where the rear motor being supplied with 3.4 kW while the car is parked in order to warm up the battery pack for charging.

It is pretty common knowledge now that Tesla drives the motor inverter in a way that is inefficient on purpose to cause the motor to provide heat. This works while standing still (the motor is stalled) or while driving (the motor is driven inefficiently).
 
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CyberGus

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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?
 

CyberGus

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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.
 

Crissa

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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?
High temps. Low temps don't damage Lithium batteries. At least not temperatures that won't damage the steel.

And having a frozen gate keeping it from heating up or a failed coil wouldn't be noticed until it was really needed.

-Crissa
 

Bill906

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The older Model 3s (like mine) did not have a heatpump and have a PTC heater for the cabin only. The way they heated up the battery pack was to run the drive unit in a way that's inefficient in order to heat up the coolant that circulates through the battery. Here's a video from one of the same sources as listed in another post where they show how the Octovalve + heatpump work. This video shows how the Superbottle works in the older cars (before there was an Octovalve + heatpump)

Here's another video that shows CAN bus data from an older Model 3 where the rear motor being supplied with 3.4 kW while the car is parked in order to warm up the battery pack for charging.

It is pretty common knowledge now that Tesla drives the motor inverter in a way that is inefficient on purpose to cause the motor to provide heat. This works while standing still (the motor is stalled) or while driving (the motor is driven inefficiently).
Thanks. I guess they do use the drive motor and inverter for heat generation only. In the industrial world it’s usually considered unsafe to send power to a motor via inverter if movement of that motor could cause harm. Maybe the same rule doesn’t apply in cars, or, more likely, the parking brake is designed to ensure unintended motion does not happen.

Thanks for the link to the video. Once again, I learned from this forum.
 

Crissa

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Thanks. I guess they do use the drive motor and inverter for heat generation only. In the industrial world it’s usually considered unsafe to send power to a motor via inverter if movement of that motor could cause harm. Maybe the same rule doesn’t apply in cars, or, more likely, the parking brake is designed to ensure unintended motion does not happen.

Thanks for the link to the video. Once again, I learned from this forum.
Well, there's brakes and sensors tracking motion. And the biggest harm is 'it heats up and wears out the electronics' but if it has active cooling then, it's not heating up!

-Crissa
 


Bill906

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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.
There was a large source of hot air in the heat pump model 3 that wasn’t in the resistive heated Model 3. (that guy talks a lot!). :)

I still think there are resistive heaters in the heat pump Model 3 to supplement the heat pump. At ambient temps that low, I doubt the heat pump is going to be able to take much, if any, heat from the air. This test just shows the newer model 3 is more capable of converting electricity into heat, whether it’s from the losses of the motor/inverter, or a resistive heater, or both.
 

Bill906

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Well, there's brakes and sensors tracking motion. And the biggest harm is 'it heats up and wears out the electronics' but if it has active cooling then, it's not heating up!

-Crissa
Agree with the brakes part but not the sensors part. If something went wrong with the inverter control, or the sensors, and the brakes were not there, unintended motion could cause the car to move. Biggest harm would be the unintended movement hurt someone. For example, car is preheating in garage, person walks in front of car to get to drivers seat, sensor failure causes unintended motion while person is in front of car. But I agree, if the parking brake is designed to hold the car in place, even if the motor applies full torque, I’d think that could be considered safe. But that would be determined by a risk assessment.

In the industrial world, something as simple as a conveyor belt with an inverter controlled motor could be programmed to stay running but hold position or hold zero speed until the next movement. Most places would not allow humans to do maintenance or even be near the belt if the motor was in that state of being energized but held at zero speed. Before humans can work on it most places require something ensures no power can be applied to the motor. Simplest way to do this is with a disconnect switch between inverter and motor, but there are other ways.

I’m not saying I’m right. I’m just explaining why I had doubts that Tesla would energize the motor for the sole purpose of creating heat, based on my experience in the industrial world.
 

android04

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Thanks. I guess they do use the drive motor and inverter for heat generation only. In the industrial world it’s usually considered unsafe to send power to a motor via inverter if movement of that motor could cause harm. Maybe the same rule doesn’t apply in cars, or, more likely, the parking brake is designed to ensure unintended motion does not happen.

Thanks for the link to the video. Once again, I learned from this forum.
It is very interesting how Tesla can get multiple uses out the one component in some of their designs. I don't believe that Tesla just relies on the parking brake to hold the car from moving while the rear motor is used to generate heat. The signal sent to the motor from the drive inverter can be timed in a way that the motor is actually stalled. That way power is being sent to it and a lot of heat is generated, but the waveforms are oriented in a way that causes the motor to not move and just vibrate in place.

There was a large source of hot air in the heat pump model 3 that wasn’t in the resistive heated Model 3. (that guy talks a lot!). :)

I still think there are resistive heaters in the heat pump Model 3 to supplement the heat pump. At ambient temps that low, I doubt the heat pump is going to be able to take much, if any, heat from the air. This test just shows the newer model 3 is more capable of converting electricity into heat, whether it’s from the losses of the motor/inverter, or a resistive heater, or both.
From the teardowns that I have seen of the heatpump (check out the Munro Live YouTube channel for some interesting videos of them tearing down a Model Y) there is no PTC (or resistive) heater in the cars with heatpumps. They can also generate heat using the rear drive unit and use that heat to help the heatpump versus using the colder outside air. This is somewhat stepped through in the Heating 4 and Heating 5 sections of the earlier linked video explaining how the heat pump works

Here's a good video explaining how the rear motor on a Model 3 works

Here's one that explains how the controls work on a three phase permanent magnet AC motor
 

Crissa

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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.

The control has both the input from the motor to know what signal it's creating and from how much the wheel is rotating.

To drive it inefficiently, the drive motor just puts out a less good phase, in fact, a phase that cannot move the motor. It can check this with the traction control sensors as well. And then the brake control sensors. And the vision inputs. So many ways for it to know if it's moving when it's not supposed to be.

If I recall, though, a Tesla is programmed to cut power to the motor when you press on the brake pedal, as well.

-Crissa

Before humans can work on it most places require something ensures no power can be applied to the motor. Simplest way to do this is with a disconnect switch between inverter and motor, but there are other ways.
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.
 

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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.
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