DC charging in service mode

[TM3A]

Hello,
I´ve already read a lot about fast charging and I unterstand Teslas way to charge fast at 50°C.
I´ve 2 years free super charging for my M3LR, and in my small town Tesla built 12 brand new super chargers, which I could use
In summer times I can charge at home for free too, but in winter I have to pay (electricity from grid) so that I would like to take advantage of the free suc.
The way to the suc is only 3-4 miles, so preconditioning in winter will be to short.
There is the possibility to deactivate battery heating in service mode, so that the battery will be slowly charging depending on the actual temperature of the cells I think.
I did´nt find much stuff about this practice, except that people on 22 or 50kW chargers wanted to do it that way and were advised against it from other users.
Question:
Aside from the charging speed being slower, does it harm the cells in any way from being charged cold and slow? (in service mode)

Best regards

 

[Rocky_H]

There is the possibility to deactivate battery heating in service mode, so that the battery will be slowly charging depending on the actual temperature of the cells I think.
I did´nt find much stuff about this practice, except that people on 22 or 50kW chargers wanted to do it that way and were advised against it from other users.
Question:
Aside from the charging speed being slower, does it harm the cells in any way from being charged cold and slow? (in service mode)

I think you are assuming too much, and I don't think any of this is possible.

But furthermore, you can do whatever you want, because the car will not allow itself to damage itself from charging the batteries too fast for the temperature that it is. If it needs to severely limit the charging power because the battery is too cold, it will do that. So the car will be fine, but you will get slow charging speeds when the battery is cold, and I don't see any purpose at all in trying to do anything in service mode.

 

[TM3A]

I thought based on the LG M50 INR21700 datasheet, what says 0.7C @25 ~ 45℃ -> 50-60kW, that limited fast charging would be generally healthier for the cells, compared to ultra fast charging at 55°C with 150-250kW.

 

[DownshiftDre]

Interesting thought. Im a fan of service mode for other features and am aware of the no battery heating option. The car will limit charge based off cell temp. But will you get to your destination in time?

 

[TM3A]

My thinking is only for my hometown suc, because I´ve 10.000 free km.
When I go on trip/holiday I would use precondition of course.

 

[Rocky_H]

I thought based on the LG M50 INR21700 datasheet, what says 0.7C @25 ~ 45℃ -> 50-60kW, that limited fast charging would be generally healthier for the cells, compared to ultra fast charging at 55°C with 150-250kW.

Well, it's a continually scaling curve. Think of a graph where temperature is on the X axis and power is on the Y axis. As the temperature goes up, the safe amount of amps or kilowatts also continues to go up. If the charging power stays below the line, that's generally safe and not damaging. The car is built to know what type of battery type and chemistry it has, so it will always keep the charging power low enough for the given temperature to not damage it. That will be a higher power at higher temperatures and lower power at lower temperatures.

But whether two different points still within that safe charging level are "healthier"? I don't know. It's getting into splitting hairs about whether you will be able to see a hypothetical difference in 10 or 20 years' time.

 

[TM3A]

To get back to the point of the original question: I need 30-35% charge per week (excluding trips). At the weekend I have time to charge at SuC (near where I live). I don't see it making sense to waste 5kWh on heating just so that the charging power is a little higher. It doesn't matter whether I wait 20 or 30 minutes on the SuC until I have loaded the 35%.I think it is good for the lifespan of the front inverter (which reachs >100°C for heating battery) and the compressor (runs full speed 9000rpm) if they stay off.

I would waste 15-20% of my free SuC miles just for heating battery.