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Longer to charge at home in colder weather?
- Thread starter metroplex
- Start date
Yeah I am seeing that they have changed quite a bit. I miss the >65kW of regen though. The app still is showing it can be as high as 85kW but it is a LIE! at least on my 2018 LR RWD. Lots of things need to be re-characterized.
The Tesla Charge Stats part of the app is misleading as it didn't seem to account for the energy required to heat/condition my battery prior to charging in the garage. So about 2.2 kWh was not accounted for in the app, plus they use an over inflated gas price to do the cost savings comparison. Gasoline is not $5.20/gal in MI (as an example).
Are you able to tell how much power is going into the battery as heat when it starts charging? I've never seen my car do this, but then again, I'm in a much warmer climate than you are.
No I don't have a datalogger that can do it. But I did compare my utilities app that shows kWh consumed per hour and how much the Tesla app showed was used for charging. The Tesla app shows the amount of kWh used to charge the battery but not account for what was used for heating the battery. The Tesla screen in the car shows the time required to charge but also appears to add in the time it estimates to condition the battery.
Basically, there's nothing else in the house that would draw that 2.2 kWh during that time other than to condition the battery. Usage was like 9.4 kWh during that total duration. Tesla app only accounted for the kWh used to charge back the battery.
I live a bit colder than that. Charged at -18-20C (about -2F) a few daya ago, at my mother in law* with the UMC, 230V 13A (3kW).
I am used to see numbers like 35 or 37% efficiency in teslafi. I have charged at down to -30C (-22F) at this position.
I use SMT with a Samsung tablet in front of the steering wheel (thanks to @eivissa for the tip) and send all data to teslalogger.
Unfortenately I did get a Sim card that only works in my home country and my mother in law live in the neighbour country so no logs for these UMC 3kW charges unfortenatly. But I can see that the car preheat until the battery is about 8-9C and before this almost no charging take place, all 3kW is used to preheat. During the charge i have seen up to 2kW for heating and only 1kW adding energy. The battery is kept at 8.75C or something like that during the charging.
This trip I did see a higher battery temp during the drive than before, this seem to be a software change. This caused the initial overnight charge to show much higer efficiency this time. (I always connect the charger directly at arrival to take advantage of the rest heat in the battery.)
Now the question is, if you connected to a EVSE that could do 12kW, would it use 3-6kW to preheat and put anything into the battery right after you plugged in? Is the reason it's not putting any energy into the battery simply because it decides it's better to use it all for preheating and it doesn't have anything to spare?
A couple of days ago we made a round trip to the big city, 200 miles plus. It was dark and 14 degrees F when we got back. We arrived home at about 27% and plugged in immediately.
It charged us up to 60% over the next few hours and was pretty efficient:
We left the car plugged in overnight. By the following morning, the car had lost 4% and when I woke it it charged back up to the 60% target. The car and battery temp fell to the outdoor temp (garage isn't heated). You can see the charging efficiency fell to 66.9%.
Screenshot from Tesla App while charging the following morning. You can see that it is only using 29 amps of the 48 available at that point. I expect that is related to the low temperature.
It charged us up to 60% over the next few hours and was pretty efficient:
We left the car plugged in overnight. By the following morning, the car had lost 4% and when I woke it it charged back up to the 60% target. The car and battery temp fell to the outdoor temp (garage isn't heated). You can see the charging efficiency fell to 66.9%.
Screenshot from Tesla App while charging the following morning. You can see that it is only using 29 amps of the 48 available at that point. I expect that is related to the low temperature.
(moderator note)
There are two slightly different discussions going on in this thread.
One discussion, started by the OP, is related to asking what the thread topic is, which is does it take longer to charge in the winter. The answer to that is, at a high level "depending on the speed of your charging solution, and weather, it could take longer because of a need to heat the battery".
The other discussion, is around battery heating itself, when / where it happens, how much, at what temperatures, at what speeds driven, how does this differ from previously captured data, etc.
Part of me wonders if I should move that part of the discussion from this thread to the one @derotam started about the topic. I am open to doing that. I dont know if I feel strongly enough about it to "just do it" but if the people having that discussion think it might be better in the other thread, but are talking here because "we are talking here", I am certainly open to moving it. Im also open to leaving it here since this is where it spun up.
There are two slightly different discussions going on in this thread.
One discussion, started by the OP, is related to asking what the thread topic is, which is does it take longer to charge in the winter. The answer to that is, at a high level "depending on the speed of your charging solution, and weather, it could take longer because of a need to heat the battery".
The other discussion, is around battery heating itself, when / where it happens, how much, at what temperatures, at what speeds driven, how does this differ from previously captured data, etc.
Part of me wonders if I should move that part of the discussion from this thread to the one @derotam started about the topic. I am open to doing that. I dont know if I feel strongly enough about it to "just do it" but if the people having that discussion think it might be better in the other thread, but are talking here because "we are talking here", I am certainly open to moving it. Im also open to leaving it here since this is where it spun up.
I haventy seen this so I can give a straight answer. The reason is, I charge at home so the charging is done just before the drive, this means starting the charging 0300-0400 in the night and then the battery has taken the ambient temp of the garage each time, which is above the limit for heating the battery. (I have 10-13C in the garage during winter time).
I could look in the data, Most probably I have arrived with a cold batt enough some time to get the batt heating to work at home)
Well, the reason for the longer time is that part of the charging power is used to heat the battery. These subjects are closely related.
If you park the car in very cold weather but with a warm battery, there will initially not be any battery heating and the charging efficiency will be about as good as any day.
To not loose the link between battery temperature and preheating, maybe ot should be kept together?
An interresting part is that in swedish forums, where we have it really cold the battery saving “charge late to reduce the calendar aging” we/ I tends to end up giving the advice for cars parked outside(or cold) to charge asap when arriving to the charger. This because the battery will be less cold at arrival so less heating is needed and when the charging is done the battery will go cold anyway which keep the calendar aging low. So, batterey heating and charging outside is closely related.
Yeah, they are somewhat related, but slightly different discussions, which is why I mentioned I dont feel strongly enough about it to "just do it". I am not trying to break up what is a pretty interesting conversation. I just thought I would make the offer since @derotam already spun up another thread that looks to be more a technical bent on battery heating (related to pre conditioning, but its definitely a more technical bent).
Pre-conditioning in route to supercharger
All right so I did a lot of categorizing how this worked in practice on a 2018 3LR RWD way back when(2018/19) but things change and while a lot of people may not care about this I feel it necessary to attempt to update this information. I also need some help brainstorming what is going on...
teslamotorsclub.com
I certainly dont want to prevent the discussion, though, so it can continue here too since its already here.
I'm the OP and am interested in the data behind why it takes longer, so I don't mind keeping it in the same thread (not closing one and moving it or whatever). The reason being that when I or someone else does a search 5 years from now, some of the threads will pop up and it wouldn't really matter if it was consolidated or not.
FWIW I don't see the heating symbol in my app. Is it for the US models or International models?
Regarding 29A/48A - I thought I saw something about a loose connection or wiring issues causing that. It was my understanding that the app should report the full current used to charge the battery and/or condition the battery.
FWIW I don't see the heating symbol in my app. Is it for the US models or International models?
Regarding 29A/48A - I thought I saw something about a loose connection or wiring issues causing that. It was my understanding that the app should report the full current used to charge the battery and/or condition the battery.
I did take a quick look at that thread and at least most of this is not realted to precondition for superchaqrging I think.Yeah, they are somewhat related, but slightly different discussions, which is why I mentioned I dont feel strongly enough about it to "just do it". I am not trying to break up what is a pretty interesting conversation. I just thought I would make the offer since @derotam already spun up another thread that looks to be more a technical bent on battery heating (related to pre conditioning, but its definitely a more technical bent).
Pre-conditioning in route to supercharger
All right so I did a lot of categorizing how this worked in practice on a 2018 3LR RWD way back when(2018/19) but things change and while a lot of people may not care about this I feel it necessary to attempt to update this information. I also need some help brainstorming what is going on...
I certainly dont want to prevent the discussion, though, so it can continue here too since its already here.
These battery heating is done during AC charging due to the fact that the battery is too cold for safe/low degradation charging despite low power. Lithium batteries can not coipe with sub freezing levels when charging. Tesla seem to set the minimum temp at 8-9C despite quite low power. A (big) part of the charging power might be needed for this, hence the low efficiency.
I have enough data to say that even slow charging at 2-3kW AC need a heated battery and if the cell temp is below 8C (about 47F) it need to be heated.
If the ambient temp is well below 8C (47F) or so, there will be battery heating needed to keep the battery temp up during the charge because the charging power is so low that the temperature can not be kept by charging only.
We can not judge the battery temp from the ambient temp When driving. When cold, the heat pump use the energy in the battery to heat the cabin. Last year the battery temp went down to 12C and then up to 17C and then down to 12C. This winter Ive so far seen going down to 12C and after this up to 17C and Staying there. Different software might work in a different way.
I dont believe all battery heating is represented by the heating symbol (I believe some people refer to it as "bacon"), but I am not someplace where its cold enough to ever see the bacon icons.
Just like we dont see the snowflake icon when the battery is "cool enough to limit regen but not cold enough to remove some capacity", I dont think we see the bacon icon for all battery heating either. If I am wrong about this, someone will correct me.
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