Large Drop in Charge When Parked in the Cold

DaveVa said:

I had V4.0 software an went to friends house. Arrived with 145 miles rated range. When leaving 16 hours later range had dropped to 102 miles rated range. Car was uncovered in the driveway overnight with cold temperatures and high winds. I have sleep mode enabled - so this is not the normal "vampire load" issue with the displays. It's just likely what the car needed to do to keep the batteries warm - both regen and power were limited in the morning.

I'm all for Tesla maximizing care of the battery pack, however it is important to communicate expected behavior. I could have plugged in to a 120v outlet at my destination, but didn't since 145 miles range was plenty to get home (100 was just enough).

Have others seen similar behavior? Will v4.1 be different?

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I believe you're the first to report this (at least in the Model S), but it's not at all surprising. It's unlikely 4.1 will be different.

One of the reasons the Bismarck was sunk was because they didn't fill up when they had a chance and that narrowed their route selection. When leaving Europe for the North Atlantic they had a chance to fill up but the Captain decided that 80% of a tank was enough for their planned course. Tesla's plug it in every night has that kind of meaning.

Interesting. That's also number 1 on the list of the three things in aviation that you can never get back: Fuel you left in the truck."

jerry33 said:

Tesla's plug it in every night has that kind of meaning.

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I think this is good anyway, because you never know what may happen. Oh, I need to run an errand. Oh, I wasn't paying attention and floored it. Oh, I'm giving my friend a joy ride before we leave. Oh, this road's closed and I have to go 30 miles out of my way. Etc. If you can plug in, IMHO, do.

But I'm quite surprised at that much of a drop, in so short a time, especially with "sleep mode" enabled!

So what happens if you leave it at an airport not plugged in for a week and a half in the winter with temps in the teens overnight and 30's in the day? Certainly plugging in whenever possible is a very good policy, but that's not going to be possible in many cases.

I agree, Tesla really does need to tell its customers what the car's behavior will be in different situations.

RDoc said:

So what happens if you leave it at an airport not plugged in for a week and a half in the winter with temps in the teens overnight and 30's in the day?

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take a different car. lol.

yobigd20 said:

take a different car. lol.

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This will be my ONLY car....

jerry33 said:

Tesla's plug it in every night has that kind of meaning.

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Always plug in. Good advice.

RDoc said:

So what happens if you leave it at an airport not plugged in for a week and a half in the winter with temps in the teens overnight and 30's in the day?

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Given what the airports charge for parking these days:

1. Park at a third party site that has plug-in facilities--even if it's only 110V (Most places where it gets that cold will have plugs for block heaters.) You might have to call around and ask.

2. Take a taxi or airport limo.

RDoc said:

So what happens if you leave it at an airport not plugged in for a week and a half in the winter with temps in the teens overnight and 30's in the day? Certainly plugging in whenever possible is a very good policy, but that's not going to be possible in many cases.

I agree, Tesla really does need to tell its customers what the car's behavior will be in different situations.

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+1

This thread is easily the one that's making me the most concerned about my pending Model S purchase. I don't travel all the time, but when I do I can be gone for days at a time and usually get back late at night. While Nashville isn't exactly the Arctic Circle, it can get damn cold in the winter. The last thing I want to find is a drained battery 20 miles from home in the middle of a cold night.

According to the Tesla Model S "facts" page (and something I've been taking at face value):

The Model S battery will not lose a significant amount of charge when parked for long periods of time. For example, Model S owners can park at the airport without plugging in.

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- - - Updated - - -

DaveVa said:

Car was uncovered in the driveway overnight with cold temperatures and high winds.

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How cold are we talking here?

Sounds to me like cold soak. A cold battery means that it has to get up to operating temperatures before regen is enabled again. There may also be voltage sag which makes capacity seem lower (will recover at optimal temperature). Did you see the range return after driving a while?

I remember the Roadster does turn on the A/C to in hot temperatures even when unplugged, but it does not do the same with the heater in cold temperatures. So it's possible for the battery to be cold soaked and then regen will be disabled (because charging the battery in the cold can damage it). Once you plug it in, the battery heater will heat up the battery before it starts charging. If driving unplugged, it will use up some range to heat the battery (see second link, it's reported as 10km/6 miles of range for the Roadster).
http://www.teslamotorsclub.com/archive/index.php/t-6977.html
http://www.teslamotorsclub.com/archive/index.php/t-7467.html

I don't know if this has changed in the Model S. Without a battery temperature gauge like in the Roadster, it's hard to tell.

DaveVa said:

Have others seen similar behavior? Will v4.1 be different?

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I reported the same thing in the Vampire Load thread the other day. I parked the car with 106 miles of range, and in the morning it was 72 miles, with limited acceleration and regen.

I'm hoping that the car will be well-behaved during the week I am leaving it parked at a friend's apartment complex while I'm traveling. There was no outlet available to leave it plugged in. It's supposed to be in the 60's during the day and the 40's at night, and it will be under cover. I am assuming that the car has some kind of threshold below which it will not continue to use pack energy to keep the pack warm.

I agree that such a large drop in range when parked overnight is quite a surprise. I had to arrange for an unexpected charging opportunity.

This is one of my biggest worries about this car. When a Roadster's battery bricked without plugged in this summer, Tesla came out and reassured the Model S can be safely unplugged for an extended period of time. If it takes 20+ miles of energy to warm the battery for 12 hours, then I don't see how one can really leave this car unplugged for more than 3 days. And suppose the battery is depleted and can't no longer warm the battery, won't this cause the same bricking problem faced by the Roadster?

The important question here is if the car has actually consumed all those "miles" (kWh) during the cold night OR if range just seems depleted at first due to the battery being cold and the battery system due to this reads a lower voltage, maybe also changes in impedance etc. which makes it think that the SOC is lower than it is/will be read once the battery comes up to proper operating temperature.

That would imply that the car was using about 800 continuous watts to keep the batteries in acceptable range over the 16 hour period. That would be A LOT given that it hasn't been THAT cold in VA the last few days. My guess this is just due to low battery temp and it would've gone up as the battery warmed, as others have said.

Tesla should be able to compensate for the reading by adjusting the range figure when the battery is cold.

Todd Burch said:

Tesla should be able to compensate for the reading by adjusting the range figure when the battery is cold.

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Might be easier said than done. What if the SOC is actually low AND the battery is cold. Maybe it gives a similar reading. I.e. perhaps the car can't know for sure until the battery is worm?

Johan said:

Might be easier said than done. What if the SOC is actually low AND the battery is cold. Maybe it gives a similar reading. I.e. perhaps the car can't know for sure until the battery is worm?

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I'm not a battery expert, but you may be able to calculate an approximate voltage sag based on temperature and translate that into a range compensation. I'm not looking for a pefect compensation, but something's better than nothing.

Johan said:

Might be easier said than done. What if the SOC is actually low AND the battery is cold. Maybe it gives a similar reading. I.e. perhaps the car can't know for sure until the battery is worm?

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In 3 winters and 48,000 miles on our Roadster they never had this problem with its battery pack.

jerry33 said:

Given what the airports charge for parking these days:

1. Park at a third party site that has plug-in facilities--even if it's only 110V (Most places where it gets that cold will have plugs for block heaters.) You might have to call around and ask.

2. Take a taxi or airport limo.

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I've never seen a parking facility anywhere in the New Hampshire or Massachusetts area with a block heater plug and we get temperatures like that almost every winter.

Certainly taking a ICE vehicle is a solution, but the OP was WRT Tesla telling owners what to expect. If the car can't be left in cold temperatures for several days without being plugged in, fine, but Tesla should make that very clear.

Johan said:

The important question here is if the car has actually consumed all those "miles" (kWh) during the cold night OR if range just seems depleted at first due to the battery being cold and the battery system due to this reads a lower voltage, maybe also changes in impedance etc. which makes it think that the SOC is lower than it is/will be read once the battery comes up to proper operating temperature.

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Now that is a really interesting question. I babied the car a bit that day because I had to make it to my friend's house where I would be able to charge. I remember noticing when I plugged the car in that it had 55 miles of range showing been though if the morning estimate were correct it would have had 36. So, perhaps the 34 mile indicated drop was a combination of a little bit of normal overnight charge loss and also a change in the estimate due to a cold pack.

I will certainly post an update when I return from my trip, and I hope that the update will not include the words "brick", "flatbed", or "AAA"!