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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.

Not having any direct experience but making educated guess:

Battery itself doesn't care about temperature, it has AC of it's own (including heater). Something like -25F could raise some range issues if your destination is far away because heater (cabin and battery) draws some energy and snow/ice is not the perfect surface for low rolling resistance.

I read a post from an Alaskan Roadster owner, who had lost 5 miles of range after 40,000 miles. Cold is good for batteries!

Ok, here is some real world experience from three weeks of daily driving my P85 in the DC area.

- You will use more energy on cold days. Cabin heat and battery pack heating use the most. Temperatures here have been in the 20s at night and 30-40F during the day. With that my average consumption has been 400 WH/mile. Not too bad but you will not get your rated mileage. When there is snow on the road this will get even worse.

- The battery pack DOES care about its temperature and is actively controlled. When it gets cold it will heat the pack and that uses energy. This may not be a problem if you are plugged in but needs to be taken into account when you leave your car in the cold unplugged (airport, work, etc.). When I left my car outside for 24h with temperatures ranging from low 40s to 20s I had 50 (rated) miles less the next morning. (That is with the newest 4.1 firmware and sleep mode enabled.) It still works for me because my commute is 80 miles but keep this number in mind when choosing your battery pack! As soon as battery heating is involved you will not be even close to the published 1% LOC per day but much greater.

- If you live in a cold climate go for the largest battery even if that means skipping options. In my experience so far I think the 40kwh battery is not going to be a viable option unless you can plug in your car whenever it is parked, ALL THE TIME.

"Cold is good for batteries!"

Cold is possibly good for battery storage. :)

It does puzzle me a bit why car loses that much energy with cold that isn't actually very cold, for storage lithium ion batteries in general like cold, they keep their charge better in cold than in hot environments (as long as electrolyte doesn't freeze).

They might not be able to release as much when cold giving you less power but energy should stay there.

Maybe it is chosen Panasonic battery chemistry that acts poorly in those kind of conditions. Or the battery coolant freezes easily and does require heater way before batteries would. Or the heat insulation sucks in Model S.

Leaf battery that has passive temperature control does much better job at keeping the energy in. That doesn't make much sense when Model S battery is allegedly so much smarter, but it is a fact.

I'm more inclined to think the temperature being maintained is higher than originally thought. Maybe by design after testing, or maybe by accident, I'm not sure.

I recently parked my 7-day old Model S (P85) overnight in Palo Alto with 49 rated miles left. Overnight temperatures dropped to below freezing. The next morning (at 32 degrees F)the battery gauge had fallen to 1 rated mile (not surprisingly, my heart went a pitterpater). Menlo Park Service Center said: not to worry, the juice is there, plug in to a nearby 110 volt outlet for 15 minutes or more and the gauge will refresh to a more accurate range. After 20 minutes the battery gauge still read 1 mile to go. Menlo Park repeated the not-to-worry advice. I made the 4-mile drive to Menlo Park on "0" charge in white-nuckle mode. I attribute my gauge anxiety to the cold but the Menlo Park folks seemed to brush it off as a curious fluke. I don't do flukes well. Anyone care to offer an opinion on the cause of my gauge anxiety? Thank you.

EDH AL I'm curious why you wouldn't simply plug the car in overnight. That is what Tesla suggests I believe. It would probably put your mind at ease your 'S is plugged in and can't easily exhaust the battery on a cold night.

@Jewsh,

Lazy and a little naive. With rated range of 49 miles that night, an appointment at Menlo Park Service Center the next morning, and underestimating the chance and effect of a freeze that night (jeez, this is Silicon Valley, not Tahoe), I simply expected the car to be o.k. and that it would also be more efficient to recharge at Menlo Park. Next time, I'll be more cautious!

Even on 120V overnight, the battery stays warm and regen is immediately available when you start. This is actually used as a technique in cold climates at present, in lieu of the upcoming timed-recharge app capability.

@ Brian
Thanks Brian, I get it now!

The key is that the projected charging time must exceed the "wait" till you use the car ... the charging must be manually terminated, not vehicle-terminated!

Well it is clear that loosing a lot of charge overnight in cold temperatures when the car is not plugged in is not an isolated event. I am sure Tesla has reasons why they keep the battery pack temperature more controlled than other manufacturers (i.e. Nissan Leaf). My guess is that they want to ensure energy deliverance even at cold temperatures. LiOn batteries do not work well when cold.

The problem I am having with this is that this has not been communicated by TM with full disclosure. The only official statement I can find is a 1% LOC per day (manual) and that the car can be left for months not plugged in and will not suffer damage (plug it in blog).

Although I agree that the Model S should be plugged in when parked we all have to realize that in real world conditions this is not always possible. When you have your car you will realize that for example not all airport parking will have working outlets available or (in my case) parking garages usually do not have accessible outlets either. Loosing 50 miles in a day when I am on a 24h shift is a lot in my opinion.

I am predicting some upset owners of the 40khw model S once that gets delivered. They WILL leave their car unplugged at times and will not be able do drive it the next day, at least in the winter. TM needs to be more open about this so people can have realistic expectations what the Model S can and cannot do.

Yes, we don't need another "bricking" -episode.

Parked my 85kW in an airport parking lot for a day and a half in 20-30 degree weather. Lost about 17 miles of reported range (4.1 software).
While we have seen reports of lots of range lost, it isn't always the case.

It has been around 15 deg F in my garage for the past couple of weeks. I have found that my Model S battery will be cold in the morning and not have Regenerative braking for about 10 minutes of driving, even though I leave it plugged in all night at 240V (NEMA 14-50). I have 4.1 software and use the 'sleep mode' where the displays are not powered when not in use. I wonder if the whole car 'goes to sleep' and quits warming the battery once it is fully charged. This might explain the cold battery, even though fully charged and plugged in. Has anyone else noticed this.

docdac;
Seems to be standard. Try the workaround: Set amperage low enough that the car will not quite be fully charged by morning, hence the battery will still be warmed and regen fully available.

I'm very thankful for all of the guys testing this vehicle in cold climates. I haven't received my 'S yet and this is invaluable info.

All the best, -J.

I drove my Sig S to Bodega Bay and parked it outside unplugged for two nights in 30-40 deg. temperatures. I lost 60 miles of rated range. But on the drive back to the East Bay, it seemed that I got some of that back (maybe 10-20) because the rated range dropped less than I thought it should have.

Do we know at which temperature the system will tend to heat up the pack ?

Thanks for the information. I'm in Evergreen, CO and am getting cold feet about my upcoming purchase. Car will be parked in heated garage at home, but may have to be parked at Denver Intl in winter months for up to a week at a time. Don't know if even the 85kw battery can handle a week's parking at 30F or less...

Would like some more factory info in battery discharge in cold temps. The only thing that I see in the owner's manual is a 1% per day discharge. I surmise that may be at LAX at 70F.

As long as battery doesn't need to heat itself and ancillary losses don't increase in cold I would guess that colder climate actually lowers the battery discharge rate. Li-ion batteries like cold. In cold you don't lose energy, you lose power.

I think that Brian gave the most practical information on this topic:

"Set amperage low enough that the car will not quite be fully charged by morning, hence the battery will still be warmed and regen fully available."

@Aerof16@aol.com, Canopy Parking off Denver International has six level I and II chargers in their indoor valet parking and covered self-park areas.

Give them a call and ask about long stays. I suppose the valet parking area, which has numerous other services (like car wash, oil change, etc.), can arrange to plug in your car 12 hours before you get back (or perhaps an hour or two each day), which you would have confirmation of from the app.

I would expect that over time more charging stations will become available.

I think Tesla might want to consider a winter battery insulation kit for the bottom of the battery.

People put in winter tires in cold weather areas, so this would be like that. You add the insulation when you change the tires, remove it when you go back to regular tires.

It could be as simple as a spray-on foam that you just scrape off later, or a rigid panels that snap in, maybe with magnetic attachment points.

Before anyone objects to magnets, the sheath of the battery is steel. Not aluminum.


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