Lack of battery heater may cause very slow SuC charging speed

[EvanLin]

According to previous info:
Tesla Model 3: Exclusive first look at Tesla’s new battery pack architecture

"Waste heat from the powertrain can be used when the car is moving, but Tesla designed a thermal controller for Model 3 that can also use heat from the powertrain even when the vehicle is parked, like at a Supercharger for example, which is important since the charge rate drops if the battery pack is too cold."

You You Xue reported charging speed of "70km for 45min" at ~15% SOC and ~-10°C yesterday.
Tesla Model 3 Road Trip

 

[kengchang]

How's the lacking a heater? Model 3 uses heat from powertrain to heat the battery pack

 

[jsmay311]

How's the lacking a heater? Model 3 uses heat from powertrain to heat the battery pack

It lacks a *dedicated* battery heater. We have no idea how many kW's of heat can be produced by the repurposed drivetrain components. If it's less than a dedicated heater could provide, then that might help explain the poor charging performance observed. (Although to be fair there have also been examples of Model S's experiencing dreadful charging performance in cold temperatures despite it having a dedicated battery heater.)

We also don't know if the motor/inverter-as-heater trick works while driving. I would guess not. So there might be situations where you're driving in the cold but not producing enough waste heat from the drivetrain to properly heat the battery where a dedicated heater could be beneficial.

 

[Xminus6]

It lacks a *dedicated* battery heater. We have no idea how many kW's of heat can be produced by the repurposed drivetrain components. If it's less than a dedicated heater could provide, then that might help explain the poor charging performance observed. (Although to be fair there have also been examples of Model S's experiencing dreadful charging performance in cold temperatures despite it having a dedicated battery heater.)

We also don't know if the motor/inverter-as-heater trick works while driving. I would guess not. So there might be situations where you're driving in the cold but not producing enough waste heat from the drivetrain to properly heat the battery where a dedicated heater could be beneficial.

I did have an experience with our ‘14 Model S during a cold winter here where the SC was very slow due to the battery being too cold. I was surprised since I had been driving it for 90 minutes before i stopped.

 

[powertoold]

Bjorn doesn't get much better with the X:

 

[AWDtsla]

It lacks a *dedicated* battery heater. We have no idea how many kW's of heat can be produced by the repurposed drivetrain components. If it's less than a dedicated heater could provide, then that might help explain the poor charging performance observed. (Although to be fair there have also been examples of Model S's experiencing dreadful charging performance in cold temperatures despite it having a dedicated battery heater.)

We also don't know if the motor/inverter-as-heater trick works while driving. I would guess not. So there might be situations where you're driving in the cold but not producing enough waste heat from the drivetrain to properly heat the battery where a dedicated heater could be beneficial.

It may be 0 kW. Whether or not any additional heat can be produced at a standstill or while rolling over normal efficiency is yet to be seen. An owner needs to post LOGS of their car heating the pack when cold.

Here's hoping someone technical can get their hands on a Model 3 so we can know facts about the car...

 

[FlyingKiwi]

It lacks a *dedicated* battery heater. We have no idea how many kW's of heat can be produced by the repurposed drivetrain components. If it's less than a dedicated heater could provide, then that might help explain the poor charging performance observed. (Although to be fair there have also been examples of Model S's experiencing dreadful charging performance in cold temperatures despite it having a dedicated battery heater.)

We also don't know if the motor/inverter-as-heater trick works while driving. I would guess not. So there might be situations where you're driving in the cold but not producing enough waste heat from the drivetrain to properly heat the battery where a dedicated heater could be beneficial.

We don't know what the software is setup for, but it's the same power circuitry that drives the motor, there is no reason for it not to be capable of 50kW or more. So it's not going to be under powered unless you are parked in a lake of liquid nitrogen. The physical limit is likely to be how fast the coolant system can remove the heat from the motor since with a stationary magnetic field the current isn't cycling through the three phases.

And again, we don't know what the software is setup for, but yes it can be used while the car is moving, it's simply a matter of aligning the magnetic fields generated by the motor coils at a less than optimal angle in relation to the field produced by the fixed magnets so instead of 10amps of current making say 100N.m of torque at optimal alignment, instead it takes 40amps to make that same 100N.m of torque and a bucket load of heat. The stationary case just requires zero torque by aligning the coil generated field N poles exactly with the permanent magnet S poles.

 

[jsmay311]

We don't know what the software is setup for, but it's the same power circuitry that drives the motor, there is no reason for it not to be capable of 50kW or more. So it's not going to be under powered unless you are parked in a lake of liquid nitrogen. The physical limit is likely to be how fast the coolant system can remove the heat from the motor since with a stationary magnetic field the current isn't cycling through the three phases.

And again, we don't know what the software is setup for, but yes it can be used while the car is moving, it's simply a matter of aligning the magnetic fields generated by the motor coils at a less than optimal angle in relation to the field produced by the fixed magnets so instead of 10amps of current making say 100N.m of torque at optimal alignment, instead it takes 40amps to make that same 100N.m of torque and a bucket load of heat. The stationary case just requires zero torque by aligning the coil generated field N poles exactly with the permanent magnet S poles.

Well, I guess it's all speculation at this point. But if 50kW (or even like 10kW) of heating capacity was available, I'd expect we'd be seeing much better Supercharging rates in cold temps than what owners have observed.

And re: when the car is moving, it could be that NVH issues would arise with such a strategy and therefore make it non-viable. (This is just a thought/guess. I've got no special insight into this.)

 

[AWDtsla]

Well, I guess it's all speculation at this point. But if 50kW (or even like 10kW) of heating capacity was available, I'd expect we'd be seeing much better Supercharging rates in cold temps than what owners have observed.

And re: when the car is moving, it could be that NVH issues would arise with such a strategy and therefore make it non-viable. (This is just a thought/guess. I've got no special insight into this.)

The youtube reviews that have been shown so far almost seems like there is 0 pack heating. So I will reassert my post above, until someone proves otherwise with real data, like power draw while heating.

 

[apacheguy]

It really doesn’t matter. The active heat target on the Model S is 8 C. After that, the pack heater switches off, even if you are supercharging. Charge rates are quite slow at 8 C and the only heating that takes place while charging is from resistive losses in the pack.

If you have a PD Model you can switch Max Battery to ON and that sets the heat target to 48 C. Then your supercharging speeds will be much faster

 

[jsmay311]

The youtube reviews that have been shown so far almost seems like there is 0 pack heating. So I will reassert my post above, until someone proves otherwise with real data, like power draw while heating.

You You Xue reported at least one instance where he plugged into a Supercharger with a cold-soaked battery and it showed 0kW going into the battery for the first 11 minutes or so before it started inching up above 0. Model S owners have reported similar instances.

If, for the first 11 minutes, it wasn't charging or heating the pack, I don't see how it would ever get above 0kW. It would just stay at 0kW.

The only explanation I can see is that the supercharger was providing some power to heat the pack that isn't displayed as part of the kW number on the screen. And for that to be the case, there has to be something heating the battery.

 

[AWDtsla]

If you have a PD Model you can switch Max Battery to ON and that sets the heat target to 48 C. Then your supercharging speeds will be much faster

As I have done many times. Even if your supercharger is 30 minutes away from where you were skiing all day, the battery is still too cold for good rates. The fact that Tesla hasn't figured out how to do this automatically, and as well for people with that button, is a huge disappointment.

 

[kengchang]

As I have done many times. Even if your supercharger is 30 minutes away from where you were skiing all day, the battery is still too cold for good rates. The fact that Tesla hasn't figured out how to do this automatically, and as well for people with that button, is a huge disappointment.

I thought they just released the battery pre-warming feature

 

[AWDtsla]

I thought they just released the battery pre-warming feature

No.

 

[apacheguy]

I thought they just released the battery pre-warming feature

It doesn’t work if you aren’t plugged in. So, basically useless if you are road tripping and need to pick up some range at a supercharger early in the morning. Max Battery works regardless.

 

[AWDtsla]

It doesn’t work if you aren’t plugged in. So, basically useless if you are road tripping and need to pick up some range at a supercharger early in the morning. Max Battery works regardless.

It doesn't matter if you're plugged in. I've tried preheating the car for over 8 hours while plugged into J1772. Feature is fake news.

 

[rxlawdude]

Well, I can only report our Flagstaff charging session with ambient temp of 42F. Got full (>100kW) initial charge, normal taper. This was not cold-soaked, however.

 

[Big Earl]

It doesn't matter if you're plugged in. I've tried preheating the car for over 8 hours while plugged into J1772. Feature is fake news.

Battery heating on the S and X will work whether or not the vehicle is plugged in. Unfortunately, it only heats it to 12C (up from 8C before the “feature” update), which is still not enough for full speed Supercharging. This temperature is usually achieved in under 30 minutes of battery pack heating, so running for extended periods of time does not increase the temperature of the battery beyond that 12C target.

That 12C setpoint is also only applicable when range mode is turned off. If range mode is on, the battery will only heat to prevent electrolyte freezing.

 

[kalikgod]

Tesla needs to have a “Max SuperCharge Rate” mode. So if nav is headed to a SuC, start heating the pack at the correct time to arrive at ~25C or so.

Optimizing to reduce SuC stop times is in Tesla’s best interest to reduce congestion.

I’m not an owner (yet), so maybe one of you could send this in a feature request.

 

[apacheguy]

LOL. So all the feature update did is adjust the active heat target on the THC from 8 to 12 C? Man, Tesla needs to be better about communicating these things.