Charging in the cold

[DayTrippin]

I decided to closely watch the charging of our M3 LR, which has had to sit outside of the garage the last week. This morning I set up charging when it was 12F out. On a Tesla wall charger with 48 amps, the car has been charging at about 4% per hour vs the normal 12%. The max charge the car is taking is 30 amps currently and it has been warming the batteries for over an hour and still at 30 amps. Sometimes it might pop up to 32-33.

It charged much faster when I plugged it in right after getting home while the batter was warm from use. So, in this cold, I'd suggest charging as soon as you get home if having to leave the car out and pre-condition (rather than charge) just before you have to drive.

Normally, I keep my SoC lower to reduce degradation due to calendar aging, but with these very cold temps, it is less of an issue having a higher SoC than it normally would.

 

[Pacernow]

Great information

 

[Iron]

So, in this cold, I'd suggest charging as soon as you get home if having to leave the car out and pre-condition (rather than charge) just before you have to drive.

I just let scheduled derparture handle it all while I'm busy sleeping.

What makes you think high SOC doesn't matter as much in the cold?

 

[DayTrippin]

Scheduled departure on pre-conditions the car, doesn't tell the car when to charge. The car charges when you tell it to charge via scheduled charging or whenever you plug it back in.

All the battery studies show that high temps with high SOCs are the way to kill the batteries in non-LFP cars the quickest. A lot of charts around here with the degradation curves at various SOCs and temps.

 

[Iron]

Scheduled departure on pre-conditions the car, doesn't tell the car when to charge. The car charges when you tell it to charge via scheduled charging or whenever you plug it back in.

All the battery studies show that high temps with high SOCs are the way to kill the batteries in non-LFP cars the quickest. A lot of charts around here with the degradation curves at various SOCs and temps.

It doesn't tell the car when to *begin*charging. It tells it when to end and the car determines how early to start, to achieve completion by that time. Pre-condition can be turned on or off when using departure,, although the battery is going to warm from charging anyway. I rather this method than charging immediately when arriving home, as the higher SOC occurs just before I leave, vs sitting overnight. Plus the batttery is still warmed from charging right before I drive, vs falling cold again.

Sitting with high SOC is worse than not, at any temp, I'd imagine.

 

[DayTrippin]

When I put in a scheduled time to charge the car, that is when mine starts charging. I am not talking about preconditioning. If possible, I plan my charging to finish just before I leave. Maybe scheduled departure is working for you and actually charges the car prior to departure.

If I use the scheduled departure time, it has never gotten charging right for me. It often, if not always, never charges the car. The only thing it gets right is to precondition the car temp or preheat the battery. Even there it almost always is at least 15-20 minutes early there so the AC/heat is just running and not even ready to leave with the car.

So I just set scheduled charging. I tried scheduled departure again today. The car was set for 55 SOC. It was at 45% charge when parked. Departure was set for 10:00 am. To get the 10% additional charge typically takes about 50 minutes. At 9:30 am, the car still hadn't started charging so I manually started charging it. Per Tesla it should calculate when it is ready but it has ever worked for either my 3 or Plaid. So I just use scheduled charge to make cure my car is charged when I need it.

 

[Iron]

If I use the scheduled departure time, it has never gotten charging right for me. It often, if not always, never charges the car. The only thing it gets right is to precondition the car temp or preheat the battery.

Try setting your departure time and off-peak end time to the same time.

 

[mknmike]

This seems to have morphed into a conversation about scheduled departure and whether it should take care of charging for us. I had no idea that is something Tesla is supposed to do for us.

Is it?

 

[Iron]

This seems to have morphed into a conversation about scheduled departure and whether it should take care of charging for us. I had no idea that is something Tesla is supposed to do for us.

Is it?

It's an option to automate charging and climate settings for convenience, comfort, battery life optimization, etc. Since you set it up, it's totally up to you.

 

[mknmike]

It's an option to automate charging and climate settings for convenience, comfort, battery life optimization, etc. Since you set it up, it's totally up to you.

I did find here that it does say charging should be scheduled based on departure time. I guess I will have to give that a shot.

Winter Driving Tips | Tesla Support

Your Tesla vehicle has several features designed specifically for cold temperatures. Learn how you can enhance your cold weather driving experience by following tips such as staying plugged in and preconditioning your battery before each trip.

www.tesla.com

And you can choose a departure time without the precondition option.

 

[Iron]

It charged much faster when I plugged it in right after getting home while the batter was warm from use. So, in this cold, I'd suggest charging as soon as you get home if having to leave the car out and pre-condition (rather than charge) just before you have to drive.

I did find here that it does say charging should be scheduled based on departure time. I guess I will have to give that a shot.

Winter Driving Tips | Tesla Support

Your Tesla vehicle has several features designed specifically for cold temperatures. Learn how you can enhance your cold weather driving experience by following tips such as staying plugged in and preconditioning your battery before each trip.

www.tesla.com

View attachment 1017999

And you can choose a departure time without the precondition option.

View attachment 1018000

Yep. So you can see why I said to use departure, vs charging soon as you get home. For one, you're not sitting overnight with a high SOC and it's more efficient than charging upon arrival and preconditioning in the morning by itself. The battery warms while charging anyway and even if initially begins charging slower (which I'm not sure of) it does not matter, since I'm asleep. Point is, it's charged by the time I'm ready to drive. Furthermore, electricity peak rates will usually be in effect when you arrive home, so might as well get used to using departure to avoid all that.