Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Is 120v enough to precondition battery in Winter?

This site may earn commission on affiliate links.
Hey guys, so I DO have a 240v wall charger but it is relatively far from the garage where I prefer to keep the car during winter. Suggestions to move the L2 charge to garage aside, I want to use a 120v outlet in the garage to "keep the car plugged in at all times" during Winter as per recommendation from the tesla website (they btw do not specify L1 or L2 with that suggestion!).

Car will go into the garage with a pretty full battery, so slow charging is not my concern, but my question is this: is 120v L1 charger good enough to precondition the battery and warm up the cabin at cold winter temps (below freezing)?
 
Hey guys, so I DO have a 240v wall charger but it is relatively far from the garage where I prefer to keep the car during winter. Suggestions to move the L2 charge to garage aside, I want to use a 120v outlet in the garage to "keep the car plugged in at all times" during Winter as per recommendation from the tesla website (they btw do not specify L1 or L2 with that suggestion!).

Car will go into the garage with a pretty full battery, so slow charging is not my concern, but my question is this: is 120v L1 charger good enough to precondition the battery and warm up the cabin at cold winter temps (below freezing)?
It's enough for charging, but you'll lose some SOC when the preconditioning kicks in. You only need to precondition at the tail end of charging session, you will still see a nice net gain in SOC.

I gained about 20% SOC prior to preconditioning, and then lost about 1% SOC (~19% net gain) when preconditioning kicked in with ~0C weather, with my M3 RWD parked outside for ~15 hours and L1 charging at 12 amps.
 
  • Like
Reactions: XPsionic
OK thanks guys. The garage is not heated, not even attached to the house, meaning it is as cold as the ambient temp.

I am not concerned at all about the SOC since the L2 charger can be used at will to boost the charge before a busy day ahead. I am MOSTLY concerned about the Tesla's recommendation to keep the car plugged in at all times... and as mentioned before, they do not mention L1 or L2... So I think I will buy a mobile connector for 15Amp outlet (did not come with my car, missed it by 2 moths, they stopped including them) and keep it plugged in while in the garage on the weak circuit. i just want the battery to be happy and last me a long time, that is really what's I am looking for...
 
YUP , OK, thanks and that is EXACTLY what i want. i don't want to use the 15amp to charge the car, only for the car to be able to warm itself up etc. and not to drain the battery with onboard electronics and preheating , etc. Actual charge will be taken care of by the L2 charger on the side of the house. Some earlier replies however, suggest that 15amp may not even be enough for that but i guess i can't go terribly wrong with keeping it plugged in to 15amp while the battery is mostly full.
 
YUP , OK, thanks and that is EXACTLY what i want. i don't want to use the 15amp to charge the car, only for the car to be able to warm itself up etc. and not to drain the battery with onboard electronics and preheating , etc. Actual charge will be taken care of by the L2 charger on the side of the house. Some earlier replies however, suggest that 15amp may not even be enough for that but i guess i can't go terribly wrong with keeping it plugged in to 15amp while the battery is mostly full.
Best to just try it honestly. I think it’s weird to have the 120 for warming and the L2 for charging, but it’s your setup, do what you like with it. 😜
 
Plugging in at work on 120v in -30, I monitored my car via TeslaFi. Like you, at work I didn’t need the charge, just want to keep the pack warm. The battery heater ran pretty much nonstop, and used up all of the available power from the charger. So I gained no charge, but I did get into a car that had a nice warm pack and full regen available, even after 8hrs in -30.

Like others have said, I did lose 1-2% preconditioning for 15mins before departure, but with the pack warmed up already I also didn’t have to deal with the blue snowflake SOC reduction. It’s very worthwhile doing, especially if you don’t need the charge.
 
I lose charge % preconditioning in my unheated, insulated garage with a 240V 30A circuit. Probably never below -10°C even on the extreme cold days, but the car needs more power than my 5.6 kW can supply.

Also I stopped preconditioning. The heater comes on pretty quick and now with the new setting to blend friction brakes in when the battery is cold you don't even lose the one pedal driving. My biggest issue with preconditioning in my garage is my windows always fog up because the car thinks it is my garage temperature for 30 minutes after I exit my garage. If I don't precondition it runs the heater correctly for the ambient temp.
 
I have only level 1 charged in below freezing temps rarely, but it worked, so I am wondering what the story is from all these folks claiming they lost charge while plugged in this way. Yes, it would take longer to heat the battery but once heated it was my impression that charging kept it warm. I don't even have a heat pump. When people say they lose power, do they mean overnight, or just during a precondition phase?
 
I am MOSTLY concerned about the Tesla's recommendation to keep the car plugged in at all times... and as mentioned before, they do not mention L1 or L2...

There's nothing magical about keeping your car plugged in all the time. Tesla just says this to keep people from forgetting and letting their battery get down to really low charge. So you can plug it in to L1 for preconditioning.... or not... It won't make much difference.

When people say they lose power, do they mean overnight, or just during a precondition phase?

They mean during the precondition phase. But if it's cold enough, L1 power won't be enough to heat the battery to a temperature where it can actually be charged (it will use all the available power in a futile attempt to heat the battery). That's not the OP's concern, though, given their L2 charging option.
 
There's nothing magical about keeping your car plugged in all the time. Tesla just says this to keep people from forgetting and letting their battery get down to really low charge. So you can plug it in to L1 for preconditioning.... or not... It won't make much difference.



They mean during the precondition phase. But if it's cold enough, L1 power won't be enough to heat the battery to a temperature where it can actually be charged (it will use all the available power in a futile attempt to heat the battery). That's not the OP's concern, though, given their L2 charging option.
How cold do you need it to be for that? When I have dinner cold level one. I plugged in on arrival
 
I lose charge % preconditioning in my unheated, insulated garage with a 240V 30A circuit. Probably never below -10°C even on the extreme cold days, but the car needs more power than my 5.6 kW can supply.

Also I stopped preconditioning. The heater comes on pretty quick and now with the new setting to blend friction brakes in when the battery is cold you don't even lose the one pedal driving. My biggest issue with preconditioning in my garage is my windows always fog up because the car thinks it is my garage temperature for 30 minutes after I exit my garage. If I don't precondition it runs the heater correctly for the ambient temp.
We have a similar set up. The car's outside charging via an old dryer circuit, maybe 5.7kW. And also we don't usually precondition.

But would really like to know how much electricity we burn just heating the battery so it can charge at various ambient temperatures.

And then, is it cheaper to charge during the day at higher temps and electricity rates, or at night when temps and rates are lower?

Gets complicated fast...

And in the winter I do tend to keep the car at a higher SOC just in case the temperatures drop so low I can't charge it with our measly 5.7kW. Wonder what temperature that would be?
 
We have a similar set up. The car's outside charging via an old dryer circuit, maybe 5.7kW. And also we don't usually precondition.

But would really like to know how much electricity we burn just heating the battery so it can charge at various ambient temperatures.

And then, is it cheaper to charge during the day at higher temps and electricity rates, or at night when temps and rates are lower?

Gets complicated fast...

And in the winter I do tend to keep the car at a higher SOC just in case the temperatures drop so low I can't charge it with our measly 5.7kW. Wonder what temperature that would be?
What do you mean you don't precondition. Is that a menu option now?
 
We have a similar set up. The car's outside charging via an old dryer circuit, maybe 5.7kW. And also we don't usually precondition.

But would really like to know how much electricity we burn just heating the battery so it can charge at various ambient temperatures.

And then, is it cheaper to charge during the day at higher temps and electricity rates, or at night when temps and rates are lower?

Gets complicated fast...

And in the winter I do tend to keep the car at a higher SOC just in case the temperatures drop so low I can't charge it with our measly 5.7kW. Wonder what temperature that would be?
I know other people more closely monitor the actual power delivery vs what the car reports. I do wish it was more accurate. What goes into the battery ultimately is always just a percentage of total power used. I've been tempted to get a whole house power monitor so I can get a better feel for that. Still, I do know what I pay for power every month and it's still way less than I payed for gas. Winter or not.

I know too that the higher your amps on your circuit the less power you waste but I could only fit a 30A circuit in my panel. If we switch our second car for an EV we will have to replace our 100A panel with 200A and then I would likely get a couple of wall chargers at 60A.
 
  • Like
Reactions: brulaz