Model 3 Battery Heating?

[derotam]

This is the message I get on screen when I tap a SuperCharger in the app, while at home plugged in (and charging). It has been between 0-5 Celsius out recently.
View attachment 468462

EDIT: not sure why the picture is sideways...

Interesting, someone else on another forum mentioned that the preconditioning message did not come on while plugged in, but did come on after unplugging and stepping on the brake. Higher ambient temp though I believe...~10C

 

[taraquin]

I think it may only be able to do 3.5kW of heating. :-( I don’t see a huge spike in shore power usage when I tell the car to pre-heat.

For the SR it won`t matter that much since battery is about 30% smaller (less cells to heat) so less heat is required to heat it, on a RWD LR however it will take quite a while. In my Model S, batteryheater uses 6kW when really Cold and 3kW when less Cold. Since the battery in the TM3 tolerates low temps better than the S and X there is less need for heating aswell. A dedicated heater transfer heats more efficiently With less heatloss, but I think the system in TM3 is a much smarter system overall. In S\X I get full regen at 16C or more, 30-40kw regen at 15C, 20kW regen at 10C, 5-10kW regen if temp is 5C, 0 regen if temp is 0C or lower) while it seems 3 gets some regen even at -5C without preheating\charging and has much more available regen at temps around 5C than Model S\X. May change a bit between different SWs though.

 

[MP3Mike]

In my Model S, batteryheater uses 6kW when really Cold and 3kW when less Cold.

The Model S battery heater is either on or off, so it draws ~6kW when it is in use. (I doubt they run it at a 50% duty cycle.)

 

[derotam]

Can we stop referencing the Model S in this Model 3 specific thread?...unless there is some kind of legitimate correlation.

 

[eprosenx]

Can we stop referencing the Model S in this Model 3 specific thread?...unless there is some kind of legitimate correlation.

I think comparisons to the S and other platforms are completely relevant!

 

[derotam]

I think comparisons to the S and other platforms are completely relevant!

Depends on the comparison.

 

[taraquin]

The Model S battery heater is either on or off, so it draws ~6kW when it is in use. (I doubt they run it at a 50% duty cycle.)

I can only read from the effect-meter. Sometimes it sticks at slightly below halv of 15kW, sometimes half of that, very consistent. Don't know why.

 

[EvanLin]

I have done that a few times. Somewhere buried in hundred of log files

Here is what I wrote down from freeway driving.
efficiency Tesla Model S 85 (RWD)
12 kW = 82%
20 kW = 87%
36 kW = 90%
42 kW = 91.5 %
50 kW = 92 %

Speed is km/h
View attachment 385777

Do you have more info or maybe a thread about driving power (kW) vs. efficiency? Very curious about it.

Can you tell me where is the efficiency data from? Thanks.

 

[David99]

Do you have more info or maybe a thread about driving power (kW) vs. efficiency? Very curious about it.

Can you tell me where is the efficiency data from? Thanks.

You can connect 'Scan My Tesla' to your can and see the data yourself. It's an android app and you need a hardware adapter to connect to your car. It shows all kinds of data that is interesting.

 

[Ullrich]

Is there a graph anywhere showing the battery drain per day or per hour as a function of outside ambient temperature when a Tesla Model 3 SR+ (50kwh battery) is left outside unplugged?

There is still so much confusion about battery heating and cooling...

• If you activate pre-heating, the battery will also heat if the BMS determines that it's required (the temperature is low enough). There is no way to specifically command battery heating to begin unless you have an S or X with Ludicrous mode and you activate Max Battery Power.

• Battery cooling will happen automatically any time the BMS determines that it's required (the temperature is too high). There is no way to specifically command battery cooling unless you turn on Track Mode in a Model 3 Performance.

Model S & X have a bespoke battery heater - a resistive heater unit that is dedicated to the battery coolant loop. It can cycle on and off but not output variable power.

Model 3 uses the motor itself to generate heat for the battery. The inverter sends an inefficient wave form to the motor that generates up to 4 kW (13,600 BTU) worth of heat and sends that to the battery pack via the coolant loop. The Model 3's BMS can vary the amount of heat that it generates. You can see how much heat is being produced on the power bar below the speedometer - it will show some power being used even though you're stopped.

The heating process is what it is and there is no way to speed it up or pre-condition it beyond what the BMS wants to do.

 

[joltheadq]

One of the more recent RichRebuilds episodes they mention adding a battery heater to a model 3 battery pack. Is this something that can be purchased online. I’d be interested in getting one for longevity purposes. It’s really important to get the pack to 40°C to anneal dendrites when supercharging.

 

[JRP3]

It’s really important to get the pack to 40°C to anneal dendrites when supercharging.

Supporting data for that statement? I can't imagine why you'd want to make dendrites less brittle, i.e. more stable.

I did some digging and in fact localized heating from increased current in a specific range does reduce surface tension of dendrites and can allow them to sort of "melt" back into a smoother layer.
Self-heating–induced healing of lithium dendrites

 

[Big Earl]

One of the more recent RichRebuilds episodes they mention adding a battery heater to a model 3 battery pack. Is this something that can be purchased online. I’d be interested in getting one for longevity purposes. It’s really important to get the pack to 40°C to anneal dendrites when supercharging.

The pack already heats to 50C when supercharging by using the motors for heat. What benefit would an additional battery heater provide?

 

[SigNC]

The pack already heats to 50C when supercharging by using the motors for heat. What benefit would an additional battery heater provide?

My only 2 cents is I think the LR RWD and the SR vehicles could do with an additional heat source as the RWD motor can't be run inefficiently enough to generate enough heat and push the car down the road at 70mph+ to arrive with a battery warm enough for max SC v2 in cold temps, much less max v3.

 

[Jaywlker]

Supporting data for that statement? I can't imagine why you'd want to make dendrites less brittle, i.e. more stable.

I did some digging and in fact localized heating from increased current in a specific range does reduce surface tension of dendrites and can allow them to sort of "melt" back into a smoother layer.
Self-heating–induced healing of lithium dendrites

This is interesting, almost what you’d not expect, right? Thank you for posting the link.

 

[camalaio]

One of the more recent RichRebuilds episodes they mention adding a battery heater to a model 3 battery pack. Is this something that can be purchased online. I’d be interested in getting one for longevity purposes. It’s really important to get the pack to 40°C to anneal dendrites when supercharging.

Weird, I'll have to watch that video to see why they did it. In any case, it gets to about that temp already via "Preconditioning", which happens if you put the Supercharger in the nav. The actual temp seems to vary on SoC, it'll be lower on arrival for lower SoC (I've seen ~32C at lowest I think). The temp will very quickly climb while charging at high rates (due to low SoC) so it's not spending long at "only" 32C either.

The pack already heats to 50C when supercharging by using the motors for heat. What benefit would an additional battery heater provide?

I could maybe see a benefit for SR+ RWD that doesn't have the extra motor to generate as much waste heat. I actually personally don't like the idea of getting the motors that hot just to heat the battery - I'm sure it's fine and engineered for that function, but I still don't particularly like it. They have to get well above 50C in order to get the battery up to that temp. A dedicated heater seems no less efficient and doesn't put any "wear" on the motors (I realise that "wear" may be negligible).