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Use of batteries when plugged in…

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Hello - M3 with an LFP. I charge nightly to 100%. Charging is scheduled at 1am and car is at 100% by 5am. When I turn on climate (up to 72 degrees F) along with steering wheel and driver seat warmer at 8am for about 15-20 mins, I notice that the SOC drops by 1 or 2 percent (max range drops by about 2-3 miles) even though the car is plugged in (granted it days ‘charging complete’). I thought the car would use street power when AC or Heater is on while plugged in? Thanks.
 
What are you using to charge, and what do you have your charging amps set to?
It’s a Tesla charger. 40amps, 240v. I have it set up to 15a when charging. Max it can go is 32 amps in the app. I read somewhere that the lower the amps the better it is for the battery on a level 2. Good point, I can increase to max amp and see how it behaves. Thanks.
 
It’s a Tesla charger. 40amps, 240v. I have it set up to 15a when charging. Max it can go is 32 amps in the app. I read somewhere that the lower the amps the better it is for the battery on a level 2. Good point, I can increase to max amp and see how it behaves. Thanks.
There's no good battery health reason to charge slower than 32 amps.

When you have the max amperage set to 15, that's the max the car will take from the wall for heating or other preconditioning. The heating and preconditioning functions can and do draw more than 15 amps at 240v (3.6kw) so any difference is coming from the battery.
 
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Just an FYI... I was surprised that when charging my cold-soaked 3 at 48 amps and turning on HVAC to get it warmed up, absolutely 100% of that 48 amps was used up warming the battery and cabin for a little while. It went to 0mi/hr of charge and predicted 24+ hours to get another 10% into the battery. This was short-lived of course, but it gives an idea what might be occurring.
 
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It’s a Tesla charger. 40amps, 240v. I have it set up to 15a when charging. Max it can go is 32 amps in the app. I read somewhere that the lower the amps the better it is for the battery on a level 2. Good point, I can increase to max amp and see how it behaves. Thanks.
All "Level 2" charging is slow charging so you don't need to lower the amps going to the car. The car charges at 250 kW at a supercharger. At home, 32 amps is only like 7.68 kW. Very slow. You can leave it set at max and get your max charging speed.

If your plug was overheating or something then turning the slider down makes sense but that would only happen if you had a bad receptacle.
 
All "Level 2" charging is slow charging so you don't need to lower the amps going to the car. The car charges at 250 kW at a supercharger. At home, 32 amps is only like 7.68 kW. Very slow. You can leave it set at max and get your max charging speed.

If your plug was overheating or something then turning the slider down makes sense but that would only happen if you had a bad receptacle.
Thank you! Makes sense. I’ll leave it at 32 amps from now on.
 
There's no good battery health reason to charge slower than 32 amps.

When you have the max amperage set to 15, that's the max the car will take from the wall for heating or other preconditioning. The heating and preconditioning functions can and do draw more than 15 amps at 240v (3.6kw) so any difference is coming from the battery.
You were absolutely right! Thank you! I set it to 32 amps, turned on climate in the morning like I have been lately for about 15 mins, and the range/SOC did not change at all! I’ll leave it at 32 amps from now on.
 
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Just an FYI... I was surprised that when charging my cold-soaked 3 at 48 amps and turning on HVAC to get it warmed up, absolutely 100% of that 48 amps was used up warming the battery and cabin for a little while. It went to 0mi/hr of charge and predicted 24+ hours to get another 10% into the battery. This was short-lived of course, but it gives an idea what might be occurring.
I only have level 1 charging at home. 120V 12 Amp

I'm finding when I get home after work (I only have a 16 km drive in slow traffic) after leaving the car outside all day (± 11 hours) at -5° C to -8°C
When I plug the car in it takes ± 2 hours before the real charging starts. Last night I arrived at 84% and after the 2 hours at 24+ hours it went down to 4 hours 45 min to complete to 100%. That is what I was getting in the summer charging time wise.

As per what I've been told that preconditioning is basically not needed. It is more for the driver comfort than the car.
@GtiMart is that not so?
 
Just an FYI... I was surprised that when charging my cold-soaked 3 at 48 amps and turning on HVAC to get it warmed up, absolutely 100% of that 48 amps was used up warming the battery and cabin for a little while. It went to 0mi/hr of charge and predicted 24+ hours to get another 10% into the battery. This was short-lived of course, but it gives an idea what might be occurring.
If memory serves me correct, the dual motor 3/Y can pull up to 14kW when cabin heating and battery conditioning. This is greater than the supply at 48 amp, 11.5kW. So in this case, you will see the car lose SOC until the call for heat is satisfied and energy is diverted to the battery.
 
I only have level 1 charging at home. 120V 12 Amp

I'm finding when I get home after work (I only have a 16 km drive in slow traffic) after leaving the car outside all day (± 11 hours) at -5° C to -8°C
When I plug the car in it takes ± 2 hours before the real charging starts. Last night I arrived at 84% and after the 2 hours at 24+ hours it went down to 4 hours 45 min to complete to 100%. That is what I was getting in the summer charging time wise.

As per what I've been told that preconditioning is basically not needed. It is more for the driver comfort than the car.
@GtiMart is that not so?
Any way to bump that 15amp service to 20amps? Have your electrician check, the wiring may be thick enough to at least give you a few more amps, 16 instead of 12.
 
I only have level 1 charging at home. 120V 12 Amp

I'm finding when I get home after work (I only have a 16 km drive in slow traffic) after leaving the car outside all day (± 11 hours) at -5° C to -8°C
When I plug the car in it takes ± 2 hours before the real charging starts. Last night I arrived at 84% and after the 2 hours at 24+ hours it went down to 4 hours 45 min to complete to 100%. That is what I was getting in the summer charging time wise.

As per what I've been told that preconditioning is basically not needed. It is more for the driver comfort than the car.
@GtiMart is that not so?
Just came across this thread. Curious why you always charge to 100%, especially if you have a short commute. Recommended daily max is 80% for better battery life.

Re preconditioning, it is for both passenger comfort and battery health (by warming the batteries).

Agree with other comments re using max current capacity of your level 2 charger. If you can time the charging so that it completes just before your scheduled departure time, the batteries will be pre-conditioned.
 
Just came across this thread. Curious why you always charge to 100%, especially if you have a short commute. Recommended daily max is 80% for better battery life.

Re preconditioning, it is for both passenger comfort and battery health (by warming the batteries).

Agree with other comments re using max current capacity of your level 2 charger. If you can time the charging so that it completes just before your scheduled departure time, the batteries will be pre-conditioned.
OP has the LFP battery, which has different recommendations for charging.
 
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