-20C : Our Tesla will not charge

[Cottonwood]

Would it really have added that many even in the cold? A 120v outlet is only 1.4kWh, which isn't even enough to offset the battery warmer. But it might have prevented at least some of the loss. Of course the battery would have been warm already if you plugged it in right when you arrived.

If all it did was reduce or eliminate the loss, charging on the lowly 120V outlet would have helped. In reality, while it might not have added a full 36 rated miles in 12 hours, I bet the gain would have been positive; anything would have helped. People often forget that the common 120 Volt outlet can help, given overnight, or better yet, days...a 50' 14 gauge extension cord is not that big.

 

[mknox]

Would it really have added that many even in the cold? A 120v outlet is only 1.4kWh, which isn't even enough to offset the battery warmer.

It might. Over Christmas I stayed at a hotel in Battle Creek, MI and only had a 120v outlet available to me. While not as cold as we're talking about here, it was well below freezing overnight. I started with a fully warmed battery having driven over 100 miles since charging and I think that helped. I did see a 2-3 mile per hour gain by morning when I came out to the car.

 

[SmartElectric]

@SmartElectric, something still seems off to me. You shouldn't have to drive the car to warm the battery before charging AFAIK.

I agree completely, but Tesla service did not. They maintained that there were no problems with the car, nor with the UMC. So, I am left with only one option when in similar conditions in the future, drive the car to raise the battery temperature, as that was sure to work.

For the first time ever, I noticed something different during the recent cold snap (same one you had problems in). I have a dedicated meter on my car's charging circuit and am very observant as to what is going on. When I started to charge my car, I noticed that the current (as reported by my meter) was less than what I expected. When I checked the mobile app, it was showing <something less than 40> / 40 amps, with 24+ hours remaining to go from about 70% to 90% SOC. After about 20 minutes, the charge current went up to 40 amps and the car began to charge (based on the now much more reasonable estimated time to complete). What I am pretty sure happened here is that the heating system was activated to warm up the battery before actual charging began. It was very cold, and I am sure this is the desired and appropriate behavior. The interesting thing to me is I have never seen this before in spite of several winters with cold temps like this. Maybe something in v7.x that makes the car more "conservative" as far as battery pre-heating goes?

Tesla told me multiple times during my conversations in email and phone that the car will not draw anything from the plug when the battery is cold soaked to -23C. The battery must be heated from itself during this initial period because drawing current from the plug would otherwise put current into the battery cells, as well as drawing current for the heater. Meaning, the plug cannot be drawn from, as there is no way to prevent current from going into the battery in this case (-23C battery temperature).

I always leave my car plugged in when parked. I have never once seen the car draw power from the wall unless a) it is actively charging, b) I have turned on the HVAC via the mobile app, or c) I have opened a door and the HVAC has come on. In other words, I've never once seen it draw shore power for battery heating on it's own. I know that it has been parked in ambient temperatures of -20 C and below at certain points over the past 4 winters. It must have to get pretty darned cold for the car to do anything on it's own about a cold battery.

One thing to be clear about, our Tesla is a garage queen all week long, getting no more than 4 km of driving daily. We then road trip every single weekend, hundreds of km of driving, up to 1000 km in a weekend a few times. So, while we drove 17000 km in 6 months, almost all of it was weekend with some evening driving. This is very different from most people, and I know you have a sizeable weekday commute, which warms the battery every day. Therefore, with a completely cold soaked -23C battery on Friday overnight, our car is in a different condition to many here on Saturday morning, where the latent heat of the Friday commute would have likely allowed overnight charging.

 

[AWDtsla]

I agree completely, but Tesla service did not. They maintained that there were no problems with the car, nor with the UMC. So, I am left with only one option when in similar conditions in the future, drive the car to raise the battery temperature, as that was sure to work.

They guys at SC's are inevitable wrench monkeys and "people people", no one that understands software or design.

Tesla told me multiple times during my conversations in email and phone that the car will not draw anything from the plug when the battery is cold soaked to -23C. The battery must be heated from itself during this initial period because drawing current from the plug would otherwise put current into the battery cells, as well as drawing current for the heater. Meaning, the plug cannot be drawn from, as there is no way to prevent current from going into the battery in this case (-23C battery temperature).

Makes complete sense, including your 0 voltage. This is also why regen gets completely disabled and no power is used for battery or cabin heater. Model S only has a single power bus. You cannot energize the output on the charger without sending some current to the battery. Although in this case I would think Tesla would be able to de-energize the contactors and simply use the charger to power the heater. But either there's a hardware limitation or more likely, Tesla just didn't think of it, as is that case with many cold weather niggles.

 

[mknox]

Tesla told me multiple times during my conversations in email and phone that the car will not draw anything from the plug when the battery is cold soaked to -23C. The battery must be heated from itself during this initial period because drawing current from the plug would otherwise put current into the battery cells, as well as drawing current for the heater. Meaning, the plug cannot be drawn from, as there is no way to prevent current from going into the battery in this case (-23C battery temperature).

That does make sense. When the car draws shore power it is basically just replenishing what is being drawn from the pack. I guess there is a point where Tesla does not want anything at all going into the pack until it is warmed to some value. Mine must have been just that bit "warmer" where they could allow shore power for pre-heating. Does kinda make you wonder why they are so emphatic about keeping the car plugged in, especially when it's cold. I suppose once it's gone though it's self preservation heating, at least shore power could then top it up again.

...and I know you have a sizeable weekday commute, which warms the battery every day. Therefore, with a completely cold soaked -23C battery on Friday overnight, our car is in a different condition to many here on Saturday morning, where the latent heat of the Friday commute would have likely allowed overnight charging.

Well, not any more. I retired as of December 31st. That may be why I saw the previously mentioned pre-heating for the first time ever with the recent cold snap. Maybe my prior long weekday trips were indeed leaving enough leftover heat in the pack that there was still some there by the weekend.

Interesting stuff. Thanks for sharing!

 

[Electricfan]

Hey, my electric blanket idea might have worked too!

 

[Lon12]

Tesla told me multiple times during my conversations in email and phone that the car will not draw anything from the plug when the battery is cold soaked to -23C. The battery must be heated from itself during this initial period because drawing current from the plug would otherwise put current into the battery cells, as well as drawing current for the heater. Meaning, the plug cannot be drawn from, as there is no way to prevent current from going into the battery in this case (-23C battery temperature).

Ok. I think this is pretty important information for us to know. So -23c (-9.4f) battery temperature is the cutoff for charging? Then we need a battery temperature display so we know what's going on. If the regen line is not showing is it safe to assume that the pack is at or below -23c?

 

[AWDtsla]

Ok. I think this is pretty important information for us to know. So -23c (-9.4f) battery temperature is the cutoff for charging? Then we need a battery temperature display so we know what's going on. If the regen line is not showing is it safe to assume that the pack is at or below -23c?

The thing should be sending alerts to your phone at this point.. What if you don't have enough energy to left in the battery to warm it up? SOL.

Could have been me a few weeks ago if I had to park outside.

 

[InternetDude]

My car sat overnight one night at the hotel, it dipped to -26C. I had no problem charging and adding range. If outside in the cold, plugging into 110V would have made the trip a lot less dramatic.

ABC = Always Be Charging, folks!

 

[SmartElectric]

My car sat overnight one night at the hotel, it dipped to -26C. I had no problem charging and adding range. If outside in the cold, plugging into 110V would have made the trip a lot less dramatic

Right, but you likely had latent heat in the pack due to driving to get to the hotel, so the charging was allowed as the pack temperature was sufficient.
Meanwhile, our car sat cold soaked for 24+ hours in -20C, leading to the refusal to charge the next day as the pack temperature was -23C according to the cars logs.

 

[beeeerock]

Tesla told me multiple times during my conversations in email and phone that the car will not draw anything from the plug when the battery is cold soaked to -23C. The battery must be heated from itself during this initial period because drawing current from the plug would otherwise put current into the battery cells, as well as drawing current for the heater. Meaning, the plug cannot be drawn from, as there is no way to prevent current from going into the battery in this case (-23C battery temperature).

Well, that's very good information to have. If your battery is low when you get to a cold destination, you pretty much have to plug it in right away or be prevented from charging. If vampire loss takes what little is left down to almost nothing, you wouldn't even be able to go for a spin around the block to internally heat the pack the next day. Then you're really in a pickle.

At that point, you'd probably take a trick from my grandfather, a telephone lineman back in the '30s. He had some sort of gas or coal-fired heating box that he'd light up and slide under the engine block to start the work truck on a cold winter morning... LOL. I think he also drained the oil in the evening and brought it inside to stay warm overnight, but I can't think of anything analogous to the Tesla!

I think we would benefit from a warning pushed to the phone app... if the temperature trend is downwards and likely to get to a dangerous point. Warn the owner that his window of opportunity to plug in and get a charge/heat going is limited. If you use most of your charge to drive to your winter cabin and forget to plug in on arrival, you might be staying a while...

 

[Ulmo]

Cheers. Wish I could have fully comprehended the fact that Tesla has not put enough logic on the car to make sure it can self-heat without needing to be driven 30 minutes, but live/learn.

This is an example of something I think Tesla should have been fixing during 2014-2016. Late is better than never. Here's hoping Tesla puts more meat into the reliability and usability. Better logic, explanations from the car to the user of what and why, and better hand-holding from the car to the person. Keep the person informed fully and do the right thing, rather than not informing the person and not doing the right thing (as the example showed).

 

[hiroshiy]

I agree completely, but Tesla service did not. They maintained that there were no problems with the car, nor with the UMC. So, I am left with only one option when in similar conditions in the future, drive the car to raise the battery temperature, as that was sure to work.



Tesla told me multiple times during my conversations in email and phone that the car will not draw anything from the plug when the battery is cold soaked to -23C. The battery must be heated from itself during this initial period because drawing current from the plug would otherwise put current into the battery cells, as well as drawing current for the heater. Meaning, the plug cannot be drawn from, as there is no way to prevent current from going into the battery in this case (-23C battery temperature).



One thing to be clear about, our Tesla is a garage queen all week long, getting no more than 4 km of driving daily. We then road trip every single weekend, hundreds of km of driving, up to 1000 km in a weekend a few times. So, while we drove 17000 km in 6 months, almost all of it was weekend with some evening driving. This is very different from most people, and I know you have a sizeable weekday commute, which warms the battery every day. Therefore, with a completely cold soaked -23C battery on Friday overnight, our car is in a different condition to many here on Saturday morning, where the latent heat of the Friday commute would have likely allowed overnight charging.

@SmartElectric, thanks for great information! That makes sense. So if we really need to cold soak under -20C, we should keep charging with low amperage all night.

 

[Cottonwood]

Tesla told me multiple times during my conversations in email and phone that the car will not draw anything from the plug when the battery is cold soaked to -23C. The battery must be heated from itself during this initial period because drawing current from the plug would otherwise put current into the battery cells, as well as drawing current for the heater. Meaning, the plug cannot be drawn from, as there is no way to prevent current from going into the battery in this case (-23C battery temperature).

Be careful what you hear from Tesla. There is an amazing amount of mis-information floating around among Tesla employees.

As an example, when the torque problems were happening with the P85D's last winter, I was on the phone with the Tesla rep in Denver. He claimed that my car was limping along on front wheel drive only. To check this out, I pulled into a parking lot with several inches of packed powder snow, and put the car in "slip start" mode, then did a pedal to the metal start. After getting out of the car, it was obvious that there were four divots in the packed powder and I still had an AWD car.

The Tesla AC charging modules have significant control over their outputs. While I agree that the battery probably needs to be connected when the AC charger is drawing power, the AC charger can certainly be controlled to manage zero net current into or out of the battery. Who knows what the Tesla algorithms in their software do, but it is certainly possible to draw only enough power to run the heater. If they want to be careful, they could even draw a small amount of power from the battery to stay on the use side.

While I am looking at some nice, white, new snow outside my window, it may be next year before I see below -23˚ C here in Colorado, but when we have another clear, cold night here in Colorado, I will do an experiment and leave my Model S out in the cold, outside of its cozy 10˚ C. garage.

We know that if you use the App to start HVAC while on shore power, the car uses enough shore power to run the HVAC, and we believe that it also runs the battery heater if range mode is off. It would be great if some folks can try App based HVAC use while on shore power in the cold.

 

[chriSharek]

I have a solution: FLORIDA!

 

[mknox]

If the regen line is not showing is it safe to assume that the pack is at or below -23c?

I don't think so. I've had re-gen completely disabled (complete with warning message on the dash) at temps well above -23C.

- - - Updated - - -

Meanwhile, our car sat cold soaked for 24+ hours in -20C, leading to the refusal to charge the next day as the pack temperature was -23C according to the cars logs.

Still seems odd to me. Okay, so Tesla says that at these temps it cannot use shore power to heat the pack... but why, when you tried to initiate a charge, wouldn't it then simply use internal power to heat the pack up until such point that it was warm enough to start actually taking shore power? (not criticizing you, @SmartElectric... just wondering out loud).

 

[AWDtsla]

We know that if you use the App to start HVAC while on shore power, the car uses enough shore power to run the HVAC, and we believe that it also runs the battery heater if range mode is off. It would be great if some folks can try App based HVAC use while on shore power in the cold.

It works. For now.

 

[Cebe]

I have a feeling it's 7.1 and hopefully the latest build that talks about "improving cold weather something or other" fixes.

I think I ran into the same problem as OP, but it's hard to tell. On one of those -23C days, I started preheating the car, turned on charging (to preheat to avoid not having regen), but 10 minutes later, it was still showing 0A in the app. Had to leave, so I ended up driving around the city for 20 minutes or so, all without regen. Eventually, by the time I got home, I had about 10kW regen available, and the car started charging just fine when plugged in.

 

[AWDtsla]

I have a feeling it's 7.1 and hopefully the latest build that talks about "improving cold weather something or other" fixes.

If I ever get it, I'll note if it actually improves something.

 

[Cebe]

Me too, but given the weather, probably not until next winter