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Battery efficiency in cold climate

I am considering reserving a Model X . I am concerned about the battery efficiency in Chicago cold weather. Anyone have any information on this? Does any own a Tesla in Chicago, and have any feedback? Your feedback would be greatly appreciated.

I can tell you about my experience in cold weather. I'm in Southern CA and my commute to work was 20 - 32 degrees this morning. I started out with a standard charge, 240miles with software update v4.1 installed and sleep mode enabled. Got to work and my mileage left was 156. I went outside around noon to show my friend the car and it dropped to 136 mileages. I'm going to call Tesla and inquire about the drop. I have a suspicion; it’s the car trying to keep the battery warm.

I just took delivery of my model S in denver last week. Last Thursday I drove it to Steamboat Springs from Boulder Colorado. Average outside temperature on the trip was 10F. The trip was 168 miles in distance over two mountain passes on snowpacked roads. When I arrived in Steamboat the rangometer showed 88 miles rated.
Two things to note. Average speed was low about 45 mph due to the weather and I did not use the heater until I hit Rabbit Ears pass with the destination assured.

I also took delivery in Denver a couple of weeks ago. Since it's turned cold in the past week, in city driving over shorter distances, the car uses around 450-500 watts per mile. (BTW, R3dStang66: I spend about a quarter of my time in San Diego, and So. Cal. cold is not in the same league as Chicago cold. Neither is Denver's, but it's closer.) Doing the math, if an 85K battery is supposed to go 265 miles, the EPA estimate is based on something around 320 watts per mile. At 500 watts per mile, the range is more like 170 miles.

When the car is cold, a warning message appears on the dash display, indicating that the battery is being warmed and the car is operating at less than its usual complement of power. (Less than usual being rather relative; a crisp acceleration still crushes the passengers back into their seats.)

Of course, you're simply not going to use up the battery in a day of driving around the city, so Jonathanfsawyer's experience may be more responsive to your concerns.

I started driving my Model S Performance in Chicago on Dec. 29th. I had the same exact battery situation. I drove in 30 degree weather starting at 245 miles. After driving 50 miles, it said I had about 170 miles left. After leaving the car in the cold for a few hours, it dropped down to 135 miles. I still had more than enough miles to get back home, but I was still a little surprised. I guess it's good to know what I am dealing with in the cold.

I took delivery in Denver 2 days ago. Using the seat heaters will use less power than heating the entire cabin. Regen does not seem to occur until the battery has been warmed up (so you are losing some energy in warming the battery & the lost regen while the battery is warming).

@ronlitvak
Agree, CA cold is not the same as Chicago cold. I just wanted to give benamrami some input.

Does the car let you pre heat the battery before you leave while plugged in so you do not waist energy on the road?

@murraypetera
I don't think so yet. You can't "start" the car till you are unplugged from the charger. Future software updates might have some version of this...

I have had a Chevy Volt for 3 months. The first thing I do when I wake up in the morning is get to my computer to start warming up the Volt. I can pre-heat the car 10 min., 2 times before I leave for work. It is awesome getting into my Volt all warm and toasty , with no loss of battery charge , as the pre-heat comes from my home juice. Tesla REALLY needs to fix this soooon!!!! We need to be able to have remote start,(While plugged in) with preheat/cool...I do hope they have this completed before I get my model S.

@Bsbomber - yes, that is a nice feature and I use it in my LEAF whenever the weather is particularly hot or cold. You can also set it on a timer to do it automatically if your schedule is steady enough.

An overnight solution some have used is plugging in to a 120V. Most of the power goes to warm battery and cabin, with only a trickle of mileage added.

The same effect can be achieved by telling the car to accept a lowered amperage; set it so that the battery isn't quite full by morning. That means it maintains warmth the whole night, and you have no waiting for regen or full power in the morning.

As soon as Apple releases the iPhone app to Appstore everybody with an iPhone and cellular coverage where the car is parked will be able to start preheating both the cabin and the battery.

A pre-heat timer is surely forthcoming in a future software upgrade. Probably together with the charge timers.

Jat: do you experience similar drops in range when parked outside in the cold as reported above with the Leaf?

When Li-Ion batteries are cold, the amount of charge that can be pulled or flow is limited. There is not a reliable way to measure battery SoC when the pack is cold. When the pack warms up to operating temp the diminished charge me be restored minus the power used to warm up the pack. Keeping the car charging on a low current draw seems to be the best solution so far. Pre-warming after the app is release will do the trick also. However if you are driving in very cold weather, the batterie might actively be warming and again in that phase SoC info is not reliable.

Here is my cold weather test drive results from today, 1/1/13:
Outside temp 7 - 11 deg F.
Accessories in use were: XM radio (moderately loud), driver seat heater at #1 level, and Climate Control set to 67 deg F, auto fan, but with 'Range Mode = On' (which limits how hard the heater/fan tries to work - see notes on software v 4.1). Overall, it was a very chilly cabin.

Drove 86.2 miles (43.1 out, 43.1 back), at steady 65 mph (cruise control), on gently rolling hills, with no net elevation gain.
'Rated Range' at start 250 miles (with warm recently charged battery).
'Rated Range' at end 129 miles. When I shut down, I got a messages saying the battery is cold, and recommended charging.
So: used 121 'Rated Miles' to go 86.2 miles (achieved 71% of rating).
The 30 mile average projected range remaining at end was 102 miles projected. So, real miles plus realistic projected range was 188.2 miles, compared to 250 'Rated', or 75% of rated miles.
Average energy use was 411 Wh/mi, with total energy use of 35.4 kWh.

I was a bit disappointed, but then again it was 7 deg out! I would have thought that the batteries would stay plenty warm, as I used them to cruise at 65mph, but apparently they got colder as the trip went on.
Next, I will try the same trip at 55 mph cruise control (tomorrow - should be about the same temp).

BTW, this was SE Minnesota on dry roads with Dunlop snow tires on 19" aftermarket wheels, inflated to 45psi.

@Siddharth...

I would like to know how the past few days have been, given the colder few days. Please let us know when you can or send me an email. I worry about my commutes to Rockford year round, both in the cold and as degradation creeps in. It will sit for up to 7 hours also before I return to Naperville.

Right now, I don't think there is any way to heat the car when you are not in it, even if it is charging. The car shuts off when you lock it and walk away, although it continues to charge. Even if you could heat the car in the morning before getting in, there is no assurance that it would be heated from your utility rather than the battery. That is because the charging likely would have been completed sometime in the night, and will not continue to top up even if the battery is depleted by the heater -- at least not until it reaches some predetermined level of discharge.

That is why the software fix/app needs to address the complex relationship between heating and charging, with the goal of having the car fully charged and warm at the time you want to begin driving, without overcharging or endlessly topping up.

ArieK asked about the Leaf. I recently left my Leaf parked at the airport for 10 days, with the battery at 9/12. When I came back the battery was at the same level, and the range estimate was only 4 km lower (4 km ~= 2.5 miles). It's not exactly cold here, but it's not warm either - temperatures from about freezing to not much above, let's say in Fahrenheit 30-45.

It sounds as if the Model S is not as good at retaining charge, or rather that it uses energy while inactive. I'd like to really know what's going on with the battery heating. I won't likely be driving the car enough to have to worry about charging it every night, and am a little concerned at how much Tesla emphasizes plugging in whenever the car is not in use.

DR;
Adjust the Amp draw rate down so the car is charged or almost charged at about the time you want it. Or if you don't need many miles, plug in to 120V.

Brian, that could get you a full charge by morning if you timed it just right, but it wouldn't get you a warm cabin. My point, however, is that this kind of function is what software is for: to take the guesswork out of it. Just set the control so that the car is fully charged and the cabin is 69 degrees at 7:30 a.m., using the most efficient and battery-friendly means to get there; while you're at it, make sure I take advantage of my utility's off-peak rate structure.

DR;
I was under the impression it did for someone, or perhaps he was referring to just the battery (to avoid regen loss).

Someone reported that if the door is cracked, the car as well as the heat will stay on (he was out sledding or skating IIRC and left the door open to play music, not realizing he was heating up the entire continent.) Might work in your garage, but might not be a good idea out on the street....

Brian, yes I believe the car keeps its battery warm, but I don't know of any way to keep the heater going. Well, yes, you could keep the car door open! Why not just put a little space heater in the car, and run an extension cord to the nearest outlet? Or how about sitting in the car all night, and pressing the brake every time the car shuts off? But as a practical matter, we must be resolved to getting into a cold car in the morning, at least until TM gives us a software enhancement or an app.

I have a Chevy Volt. In the summer in Chicago, I was averaging about 1 mile per .35 kWh for
a total battery range of about 45 miles.

In the winter, I'm using about .5 kWh of energy for each mile and the range is only about 30 miles.

I'm not sure how much of this experience applies to the model S, but based on my experience with the Volt and the comments above, I am expect a big difference in mileage between summer and winter on the model S I've reserved.

I'm in central Ohio. It's been ranging 10 to 32 F here the last couple weeks. I have not observed any noticable power loss while the car is sitting unplugged for extended periods. I was not working over the holiday so most of my driving was 0 to 50 mph some highway at 75. My observation is that the wh/mile is 450 to 550 while the car is warming up the battery with cabin heat and seat heat. Once the regen yellow dotted line is gone (assuming this indicates the battery is warm) the wh/mile goes down to around 400 to 450 depending on my driving. In 45F plus temps I was getting around 300 to 350 wh/mile with no cabin heat only seat heat. I will note some of my wh/mile is attributed to the power needed to get out of my unshoveled driveway. We had about 8 to 10 inches of snow. Note I have my wh/mile graph set for 30 miles.

There's definitely no problem with mine in moderately cold weather, but I can't claim to have any insight for how she'd behave in a truly cold climate (I grew up in Canada, so I know that's a whole different story.) It was right around freezing this morning for my drive in to work in Northern California. I drive over highway 17 from the coast, where the summit is 1,800 feet and into Cupertino back at 236 feet, so the drive isn't exactly flat. I has seat heating and climate control on for the entire trip and my average usage was 308 Wh/mi. I believe that's actually better than the EPA estimate so I'm extremely pleased.

There's definitely a huge difference between driving a typical car and "one foot" driving in the Model S where I completely avoid the brake whenever possible. I turned creep off yesterday when I got home because it felt too much like an automatic and it interferes with using regen to slow the car to a stop.

... so I'd be curious to hear from people as the seasons change and find out what range of temperatures seem to have an impact, and how much relative to a 32F reference point.

@james: Wow, after reading a bunch of posts on this forum about the speed with which the Model S loses charge when not plugged in I find it amazing how well your Leaf is able to hold it's charge while unplugged!
The thermal management of the Leaf has been pretty much openly ridiculed on many occasions so I find it even more surprising how well it deals with this specific situation. It has most certainly risen in my esteem and the 2013 model is only getting better, range wise. If the fundamental layout and chemistry isn't changed much I would expect it to remain equally proficient in keeping it's charge.

It has been between -5 and +28 degrees Farenheit in Oslo for the last weeks , and its normal from november to march.
I really expect Tesla to launch a preheating function that works both plugged and unplugged, before they start deliveries to Norway (the second biggest marked for this cars in the world)

Or else it would be necessary to install a Webasto or Ebersprächer heater. (I dont want that smell...
and I would get a bad feeling when filling diesel or gasoline into this premium EV. )

I also expect to see official longterm testresults from this kind of climate and topography before I buy it.
A local Toyota salesrep told me that they dont believe the Rav4 EV (built by TM) could be sold or used in our climate and topography.

But for now, I really appreciate the feedback from the american owners with simular climate.

I know that somebody in TM actually is thinking of us here in the north, beacause when I discussed useless "all year" tires with a rep at the local TM showroom, another rep suddenly came out and said that they just decided to offer "real" winter tires.

One example of "non working batteryopreated device" over here, is iPhone. When we take them out of my pockets in cold weather to send a message or take a picture, it dies an tell us to charge. Even if it has 80% battery left. (This is not the right thread for mobiledevices, so please dont comment this..)

TS;
actually, that's a problem for those hoping to use the mobile app. "Only works when your mobile device is warm." Strictly a battery problem, of course. Circuitry works better when cold. Loves liquid nitrogen.


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