Battery warranty and temperature below -30C (-22F)

Does it ever stay that cold for 24 hours straight or is that just the nightly low on occasion?

pgiralt said:

Does it ever stay that cold for 24 hours straight or is that just the nightly low on occasion?

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Depending upon where you live it can stay that cold, or colder for more than one day.

I do beeline my owners manual states -20, and that it would only be of the vehicle is not plugged in. if plugged in, even on a 120, it will have ample power to keep the batteries in their happy place

We have a couple weeks a year of -30 or below, and is not just at night. 99% of the time I can say the vehicle would be indoors (unheated garage, but still at least 10 degrees warmer) and plugged in at night so not over 24 hours outdoors. However that is much different than saying it will never be outdoors below -30c unplugged for over 24 hours.

Until there is a power outage . This past winter was hairy for some Canadians

At least the power outage thing is one I don't really have much to worry about. Having lived in Calgary for 35 years, I've only once had a power outage longer than about an hour, and that was scheduled a month in advance by the power company. I know for the eastern folks that's hard to imagine, but the electric grid out here really is that reliable.

green1 said:

At least the power outage thing is one I don't really have much to worry about. Having lived in Calgary for 35 years, I've only once had a power outage longer than about an hour, and that was scheduled a month in advance by the power company. I know for the eastern folks that's hard to imagine, but the electric grid out here really is that reliable.

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That's also hard to imagine for us western folks.

@Matias - I've mentioned this in other threads... PLEASE bring this issue to the attention of Tesla directly (via email so you can have an extended, formal conversation) so that it officially addressed and Tesla's attention is raised on the important for folks, um, "far from California weather". Thanks.

Matias said:

I mailed them yeasterday :smile:

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Thanks.

This waranty issue has come up before, but Tesla has not addressed it yet. They really should alter the language to allow storage below -30 when plugged in.

GSP

Keep that e-mail and even better would be if you distribute it From what I remember last time I wrote about that to Tesla all I got back was that they think it's ok when plugged in, but that the warranty doesn't specify that.

Problem is, I can't guarantee that I can keep it plugged in at all times. For example I regularly travel to places where I can not plug in, and spend over-night or longer. I can not guarantee that I can always have the vehicle plugged in if it's -30c or lower.

The reason for being plugged in is to maintain power. The pack heater will kick in regardless of parked or not once the pack reaches a Tesla Pre-Determined tempetature. The pack heater will drain power from the pack to keep it warm. When not plugged in, the pack will eventually die. The idea, is being plugged in, even to a low voltage low amperage source, it will still have enough (though barely) power to keep the pack at operating temps without overly draining the battery. Since most will have it plugged into a higher power source, no problem at all using grid power to heat the pack.
The problem becomes, once the pack is too low, no more heating, and no driving to recharge.

The technical reason for this is because -30C is the freezing point of most lithium-ion electrolyte and 24 hours is enough time for the battery to cold soak. The battery can be damaged from frozen electrolyte. Presumably when you have it plugged in, the heater can keep the battery from freezing. The most Tesla can do warranty-wise (without changing the chemistry) is extend the amount of time they allow unplugged (given a more accurate cold soak time-frame), but I don't think Tesla will change the temperature nor remove it completely.

The Leaf has a similar provision, but it's for -25C and 7 days. However, the external surface area and shape of the two packs are different, so heat exchange will also be different (so don't expect 7 days for the Model S).

Matias said:

Li-ion battery doesn't contain water, afaik. Most liquids won't expand when freezing. Water is exception. So freezing is not necessarily that bad.

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The lithium battery clearly doesn't contain water (otherwise it would freeze at 0C). However, it does contain liquid electrolyte that freezes at -30C:

The electrolytes used in commercial lithium-ion batteries freeze at approximately –30C and thus their use is limited at lower temperatures.

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http://www.arl.army.mil/arlreports/1999/ARL-TR-1879.pdf

Damage to other components in the cell can occur from the freeze-thaw cycle of the electrolyte.

You seem to be thinking of solid-state batteries which have no liquids, however, they are still in experimental state (all the lithium-ion batteries in EVs today have liquid electrolyte).

Matias said:

Battery pack coolant most likely contains water and some antifreeze. If it freezes, it can rupture coolant channels. However, it's freezing point is most likely clearly lower than -30 C.

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The Leaf battery pack contains zero coolant, yet it has a similar lower temperature limit. So it's pretty apparent that it has nothing to do with the pack coolant.