Outside Cold Wx (10* F) Charging Strategy

[Leeclanual]

Normally keep my M3 garaged but going on a road trip next week. The J1772 destination charger is outside and the forecast temp is 10-15* F. When I plug in for the night should I also set the climate on to a certain temp (50-60-70*) or just let it charge in the cold wx and cold soak until morning and then preheat before using it? Maybe 45 mins preheat before driving?

 

[SSedan]

Yeah just preheat before leaving. When I got up it was -18f 45minute preheat was good.
Now granted I have an S so there is a dedicated battery heater.
Cabin was nice and warm.

 

[Sophias_dad]

45 minutes of preheat is excessive at +10f, IMHO. The cabin and seat heaters are very fast in the 3, and I assume also S/X.

10 minutes is more what I'd do. If you are planning to preheat for 45 minutes, you might want to schedule the charge to start at whatever particular time so the battery is fully and freshly charged when you drive away. But be aware, a 10f battery will be slow to charge for at least the first 20 minutes. If you are also heating the cabin on a J1772 of unknown power, you might get no charge at all for quite some time. I wouldn't chance it... just fully charge when you get in each night so the J1772 doesn't have to fight to warm the battery.

 

[Visscher]

My X has never been in a garage. And I live in Northern Canada. -30 here and I just cabin heat for 5 min before leaving for work as well as starting to charge.

 

[Sophias_dad]

Of course, OP is from Northern Virginia, so the heavy parka and mittens come out whenever the temperature drops to 50.

 

[Leeclanual]

Of course, OP is from Northern Virginia, so the heavy parka and mittens come out whenever the temperature drops to 50.

Yep... body or car isn’t accustomed to the arctic north of PA... so busting out the winter parkas. Thx for the inputs I’ll just preheat before departing hotel each morning.

 

[ivan801]

I know we all live in different climates and I mean no disrespect, but 10F is not cold. I bit chilly perhaps. I would consider -10F as sort of cold.

 

[Leeclanual]

I know we all live in different climates and I mean no disrespect, but 10F is not cold. I bit chilly perhaps. I would consider -10F as sort of cold.

It’s all perspective... someone who lives in Greenland or northern Alaska might think -10* F is balmy... I’m originally from Hawaii and anything under 60* is cold.

 

[Alketi]

Leeclanual, to pre-heat the cabin, all you should need is about 10 mins, give or take.

The bigger issue you're going to have is that the car will have zero regen in the morning. The car will literally act like it's coasting in neutral when you take your foot off the accelerator.

Since Tesla doesn't yet allow us to set a charge END time, if you want to try to automate this, you can set a charge START time such that the charging ends just before your estimated departure time. You'll have to do the calculations yourself.

Another way to handle this is to manually stop the charge (via phone app) at night, leaving yourself 30+ miles of headroom, and then manually start the charge an hour or so before you leave in the morning. This will heat up the battery and give your regen.

 

[ucmndd]

Leeclanual, to pre-heat the cabin, all you should need is about 10 mins, give or take.

The bigger issue you're going to have is that the car will have zero regen in the morning. The car will literally act like it's coasting in neutral when you take your foot off the accelerator.

Since Tesla doesn't yet allow us to set a charge END time, if you want to try to automate this, you can set a charge START time such that the charging ends just before your estimated departure time. You'll have to do the calculations yourself.

Another way to handle this is to manually stop the charge (via phone app) at night, leaving yourself 30+ miles of headroom, and then manually start the charge an hour or so before you leave in the morning. This will heat up the battery and give your regen.

+1

Start your nightly charge such that it finishes close to your departure time the next morning.

 

[guapopoppo]

left car unplugged and outdoors for 40 days. When I returned the battery lost 200 mi charge. Temps were 25-45 degrees

 

[ivan801]

It’s all perspective... someone who lives in Greenland or northern Alaska might think -10* F is balmy... I’m originally from Hawaii and anything under 60* is cold.

Ah, that explains it. Yes, I would agree that for a Hawaiian -10F may seem very cold. However, for Tesla, when we talk about cold I would say that you will not see any major issues or difficulties until it gets to temps where ICE cars start to struggle, or around -30F. At that point charging the car overnight outside on a lower powered outlet (even 240V with lower amps) will become an issue, and the car may keep a significant portion of the battery in reserve. But at those temps your ICE would for sure require a block heater, so no matter what you drive you will need to plan for it.

@Visscher posted above that she or he park their car outside in -30C (that's about -20F). Any comment on charge rates and car performance at those temps?

 

[SigNC]

I don't really think you will have much in the way of any issues. My only advice is when you leave to drive back, assuming it's a decent distance, have enough charge in the battery so that you are driving 1 or 2 hours before you hit a supercharger so your battery is nice and warm. If you don't, you will be at the supercharger a lot longer than you think.

 

[Big Earl]

20 minutes of preheat is sufficient.

 

[ArcticStation]

I concur with guapopoppo’s recommendation above. Assuming that mine would be the only EV charging overnight, here is the approach I would use.

I would leave the car plugged in and slow charge throughout the night until time of departure the next morning. Plug in, wait until rate of charge stabilizes, then dial down the rate of charge so that you reach the SOC required at the time you plan to leave. Note: Be sure to turn off the heat for a more accurate rate of charge. By starting the charge immediately upon arrival and keeping a charge going to the battery throughout the night, even at a low rate, you should be able to maintain a significant amount of battery heat. In the morning, preheat the car five minutes before you leave.

I understand that there are some inefficiencies to using a low rate of charge, so I only do this at home when below zero temps overnight are forecast. However, this is not an issue at a destination charger. Of course, avoid this approach if others are waiting to use the destination charger.

 

[Big Earl]

I concur with guapopoppo’s recommendation above. Assuming that mine would be the only EV charging overnight, here is the approach I would use.

I would leave the car plugged in and slow charge throughout the night until time of departure the next morning. Plug in, wait until rate of charge stabilizes, then dial down the rate of charge so that you reach the SOC required at the time you plan to leave. Note: Be sure to turn off the heat for a more accurate rate of charge. By starting the charge immediately upon arrival and keeping a charge going to the battery throughout the night, even at a low rate, you should be able to maintain a significant amount of battery heat. In the morning, preheat the car five minutes before you leave.

I understand that there are some inefficiencies to using a low rate of charge, so I only do this at home when below zero temps overnight are forecast. However, this is not an issue at a destination charger. Of course, avoid this approach if others are waiting to use the destination charger.

This is an effective method of keeping the battery warm all night, but it will waste more energy than charging quickly. The reason? The pack must be heated to a certain temperature before it can accept a charge. The longer the pack stays warm with exposure to the cold elements, the more heat will be lost to the atmosphere. At 4 kW charge rate for about 11 hours at 0F, I pulled 46 kWh from the wall but only 36 kWh made it into the battery. A higher charge rate for a shorter period of time would have gotten that closer to 40 kWh into the battery.

 

[PremiumPackage]

Only chiming in to say after experimenting with preheating over the last 2 weeks, here are my results:

5 minutes is plenty to get decent heat, even from -20F.

One day I preheated for 90 minutes, plugged in. Didn't lose any charge, AND regen braking was at about 50% (that's the best I've seen in the last 2 weeks)

 

[Leeclanual]

Started charging 2 hrs before departing... cabin temp set to 70... after 15 mins M3 finally started charging at 29mi/hr... and when I departed house fat 2 hr point full regen braking and 300 miles range available... and a toasty cabin. I will say that driving in hills/mountain around PA in 15* temps really sucked the energy away... arrived at my destination with 20 miles remaining (210 mile trip)... so used extra 90 miles energy.