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Preheating battery in cold weather use.

Anyone with experience parking their Model 3 outside in cold/snow conditions? Unlike the Model S/X, the Model 3 does not have a dedicated heater for the battery, and I am curious to know how preconditioning/heating the battery in the Model 3 works. I understand that the Model 3 uses software to direct heat from the drive train even when parked to warm the batteries. Having only a one-car garage, we will have to rotate the two 3's between a 220plug in-garage, and a 110plug on the exterior. How will our Model 3's hold up in extreme cold weather conditions?
 
It takes a long time... I parked my car I. My insulated garage, 32F, outside temp 20F. Took about an hour for all Regen available and loss of efficiency with cabin heater to 320Whr/mi.
Thanks for the reply Shoal007. Sorry, but just to clarify, did you mean your car was parked outside in 20F weather? Obviously the pooled experience regarding the Model 3 performance in cold climates is limited at this point, but it would be nice to see more people share their experience as I think it is an important aspect of owning one. If your car was parked in your garage and it took an hour to precondition for regen, then there are real concerns for anyone that might have to leave the car parked overnight in real cold weather. -25C is not rare for winter weather in Canada.
 
Thanks for chiming in. I would agree Rockster, but both of our cars are Model 3's, first delivery in June 2018, so it won't make any difference in our case. The best we will be able to do is rotate every second night, every third if we include a possible addition for our daughter. I am just trying to get views from the collective experience here as to what we can expect. This is a major design difference from what we understood regarding the Model S and X design. I have to hope at this point that Tesla took into consideration that the Model 3 will be used in cold climate regions when they redesigned the thermal regulation system of the battery. I am hoping that this means the Model 3 can adequately warm the battery when needed. Canada and large parts of Europe as well as China will have to deal with extreme cold weather for the foreseeable future. The other question this opens for me at least is whether long preconditioning periods (2-4 hours) needed to keep the battery warm during extreme cold weather has any negative impact on the motor in terms of wear-and-tear? I think this is a very relevant topic that this community should actively explore, and I hope others with real world experience see the value in sharing. Obviously we only have the last winter season in the USA to draw from. Cheers.
 

Rocky_H

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Feb 19, 2015
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Unlike the Model S/X, the Model 3 does not have a dedicated heater for the battery, [...]This is a major design difference from what we understood regarding the Model S and X design. I have to hope at this point that Tesla took into consideration that the Model 3 will be used in cold climate regions when they redesigned the thermal regulation system of the battery.
I want to make sure this is clear, because some people have a misunderstanding of this. Some people saw articles on this and think there is no heating for the battery at all. That's not the case. The Model 3 doesn't have a single-use piece of equipment that is a heater only inside the battery pack. It does have a way to actively heat the battery pack. It uses a way of running current through some of the coils in the motor and then sending that heat through the battery pack. So yes, it is a different method of battery heating, and maybe you are asking for experiences with the effectiveness of it.
 
Thanks Rocky-H, Yeh that is precisely what I was asking about, I would like to get an idea of how well the new method works. i.e. can it warm the battery in -25C weather while plugged into a 240V 40amp plug? I plan on upgrading the exterior plug and purchasing a first GEN UMC in an effort to help with this situation. Thanks for your input.
 

David99

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Jan 31, 2014
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The Model 3 uses the motor and inverter to heat the battery. They run power through the motor without creating torque so all that energy is turned into heat which then warms up the coolant and the battery. I don't think anyone knows how much heating power it can produce this way. I would assume similar to what the Model S/X does (aprox 6 kW).

The battery in the Model S is heated that way until it reaches aprox 8 or 9 degree Celsius. From there on the heat losses in the drive train continue to warm up the battery. The battery still has some restricted power so regen will be partially limited. It goes away when the battery is aprox 20 Celsius. I assume the Model 3 battery has similar characteristics. Only with access to the CAN bus would it be possible to test this all out.

It is definitely a good idea to keep the car plugged in while it heats the battery. I did a test once measuring the energy consumed for heating the battery from being cold soaked parked outside at -25 Celsius over night. It used aprox 7 kWh. That included cabin heating as well. Again that was with the Model S but since the battery is roughly the same size and weight, the numbers would be similar.
 
The Model 3 uses the motor and inverter to heat the battery. They run power through the motor without creating torque so all that energy is turned into heat which then warms up the coolant and the battery. I don't think anyone knows how much heating power it can produce this way. I would assume similar to what the Model S/X does (aprox 6 kW).

The battery in the Model S is heated that way until it reaches aprox 8 or 9 degree Celsius. From there on the heat losses in the drive train continue to warm up the battery. The battery still has some restricted power so regen will be partially limited. It goes away when the battery is aprox 20 Celsius. I assume the Model 3 battery has similar characteristics. Only with access to the CAN bus would it be possible to test this all out.

It is definitely a good idea to keep the car plugged in while it heats the battery. I did a test once measuring the energy consumed for heating the battery from being cold soaked parked outside at -25 Celsius over night. It used aprox 7 kWh. That included cabin heating as well. Again that was with the Model S but since the battery is roughly the same size and weight, the numbers would be similar.

Thanks for your input David99 and the much appreciated positive outlook. I especially appreciate your insight into power usage to rewarm in cold temps. It doesn't seem reasonable to me that Tesla, or any other car maker for that matter, would neglect something so obvious as heating, but you can understand my concern living in Canada and finding out that the Model 3 doesn't actually have a dedicated heater for the battery, coupled with individual reports of low thermal regulation performance in moderate temperatures. I am expecting that Tesla could also tweak the system with software if need be. Your post does raise another question for me though. My original reaction to this was to upgrade the exterior plug with a 50amp breaker to be able to use the full 40amp capacity of the original GEN1 UMC. Do you think the slower rate of charge with the 32amp GEN2 UMC would be better for battery life? If I take from the experience that others have posted here, the logic follows that maybe a little slower charge especially when dealing with cold weather issues, would be better for the battery's longevity. Any thoughts?

Dumb question here:
How does one precondition/heat the battery?
Do you just turn on the car heater to max?

Not a stupid question at all TesSpartan. It might be better for someone with actual experience to respond, but from what I understand reading from other Model S owners that have posted here is that preconditioning of the battery in cold weather is done from the Tesla app on your phone and is separate form heating the cabin.
 

Rocky_H

Well-Known Member
Feb 19, 2015
7,838
9,861
Boise, ID
Your post does raise another question for me though. My original reaction to this was to upgrade the exterior plug with a 50amp breaker to be able to use the full 40amp capacity of the original GEN1 UMC. Do you think the slower rate of charge with the 32amp GEN2 UMC would be better for battery life? If I take from the experience that others have posted here, the logic follows that maybe a little slower charge especially when dealing with cold weather issues, would be better for the battery's longevity. Any thoughts?
The question itself is valid about whether slower = better, but you need to remember what numbers context it is in. At Superchargers, they use power levels up to a little over 100kW. Slower than that? Yes, probably better. But this 40A or 32A question you are asking about for home charging is the difference between about 7kW or 9kW. They are both so extremely low power from the battery's perspective that there is no difference.

So someone should know by experience if that when you heat the interior, that is what is used to heat/precondition the battery.
There is an answer to this now. Battery preheating functionality was added about December 2017. Here is a thread about it.
Battery Pre Heat Available in App now! | Tesla
It will only do it if it's about freezing or below. There isn't a separate button for it, but if you turn on the cabin preheating in the app, and you see a little snowflake show up in the picture of the car, that is running the battery preheater as well.
 

David99

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Jan 31, 2014
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My original reaction to this was to upgrade the exterior plug with a 50amp breaker to be able to use the full 40amp capacity of the original GEN1 UMC. Do you think the slower rate of charge with the 32amp GEN2 UMC would be better for battery life?

Based on the info I have gathered throughout the years I would say it makes little to no difference for the battery life/health charging to 32 vs 40 Ampere. If I had a Model 3 I would definitely go with the 'old' UMC and charge to 40 AMP. Tesla had it on their website at some point showing how long it takes to charge at different speeds and also how efficient it is. It showed that charging at a lower rate is slightly less efficient. One reason is that during charging the coolant pump and other systems are running using some energy. A longer charge time uses those system longer thus using more energy total. The other reason is that the charger is most efficient near it's rated power. At partial power it's not quite as efficient (that's quite normal for power electronics). So there is some advantage overall to charge at 40 vs 32 Amp.

... from what I understand reading from other Model S owners that have posted here is that preconditioning of the battery in cold weather is done from the Tesla app on your phone and is separate form heating the cabin.

Actually you can't start the battery heating from the app. At least not in the S or X and I assume the 3 is the same here. The car decides when to use the battery heater or not. There is no switch either in the app not in the car to start or stop the battery heater. When you start your cabin heater from the app and the battery (not the ambient temp!) is below 8 or 9 degree Celsius, the battery heater will also start. If you get in the car and start driving and the battery is below 8 C, the battery heater will start. Recently Tesla updated the app to show the activity of the battery heater in the app, but not a way to switch it.

Two exceptions: The performance cars have a setting called 'max battery power'. When turned on, the battery heater will start and bring up the battery to 40 C. At that temperature the battery has the best power output and is most efficient. The other exception is the 'Range Mode' option. When turned on, the car will not use the battery heater.

Last but not least, the car will always use the battery heater if you are trying to charge it and the battery is below 0 C. A lthium battery can't be charged when below freezing. It would be damaged.

If the car is parked it will never turn on the battery heater, no matter how cold it gets.
 
Last but not least, the car will always use the battery heater if you are trying to charge it and the battery is below 0 C. A lthium battery can't be charged when below freezing. It would be damaged.

If the car is parked it will never turn on the battery heater, no matter how cold it gets.

So in effect, It is imperative to keep the car plugged in during cold months? What if car is at airport in winter in Canada for one week, unplugged (no plug in was available). What should I expect to have to do when I get in the ice cold car upon return?
 
Not sure this is relevant but yesterday mornin the outside temp was 59 degrees and had been about 50 overnight. In the morning we drove about a mile to the supercharger. At 52% charge level we started to charge at 32 kW and very quickly dropped to 28 kW. Long story about moving to different stalls, rebooting, calling Tesla, etc but the charge level did not change until about 80% level. Then the charge level dropped to 26 kW.

Later that same day, after driving about 150 miles and charging at a destination charger we returned to the same supercharger. The charge level was normal at about 100 kW.

We had charged normally at this same supercharger two days earlier.
 
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Reactions: Kermee and jsmay311

David99

Active Member
Supporting Member
Jan 31, 2014
4,909
7,353
Nomad (mostly US)
Not sure this is relevant but yesterday mornin the outside temp was 59 degrees and had been about 50 overnight. In the morning we drove about a mile to the supercharger. At 52% charge level we started to charge at 32 kW and very quickly dropped to 28 kW. Long story about moving to different stalls, rebooting, calling Tesla, etc but the charge level did not change until about 80% level. Then the charge level dropped to 26 kW.

Later that same day, after driving about 150 miles and charging at a destination charger we returned to the same supercharger. The charge level was normal at about 100 kW.

We had charged normally at this same supercharger two days earlier.

Battery temperature had most likely nothing to do with it. Worst case the battery would have been 50 degrees. That doesn't cause a Supercharger to slow down to less than 30 kW.

I have Supercharged about 900 times with my car at over 100 stations. I also have a tool to monitor my actual battery temperature and other data from the car. My experience with Superchargers not delivering full power is pretty random. Calling Tesla has never ever helped. The people that take the calls have no special knowledge. They were never able to tell me why or what is going on. In 90% of the cases, their standard answer is there are variations and that's what it is. They are trained to go through standard situations but their knowledge ends after telling you about stall pairing or a 'busy station' or cold or hot temperatures. Here and there they confirm the station is known to have issues, but that's it.
 

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