Cold Battery Degration By Charge Amount

[ngogas]

i know that battery degrade quicker from cold weather. But has anyone seen or have scientific proof that EV battery degrades quciker at certain battery charge levels?

I am curious if 50% charge degrades at a quciker rate then say 85% and so on? Or none at all?

 

[SSedan]

I believe you are wrong in your basic premise, heat hurts batteries but the cold weather always made it present in lead acid batteries because the cold slows the chemical reaction and exposes the reduced capacity.
I think that is where you are getting the idea from.

 

[ngogas]

I meant degration in terms of losing the charge quicker. Not overall degration of battery.

 

[TexasEV]

I meant degration in terms of losing the charge quicker. Not overall degration of battery.

Wrong again. Batteries have lower capacity in the cold. The car uses more energy to move through cold air. Cold batteries do not discharge quicker.

 

[Stretch2727]

Need to think of it this way....

Cold minimizes battery degradation. (maximize life of LI battery, Heat is what kills LI battery life)
Cold minimizes performance of battery. (lower range, less regen, etc)

Higher charge level (100%) is best avoided in hot and cold.

 

[Vintre]

I think you are asking if SOC goes lower quicker or slower depending on the start SOC.

If so, here is my data point.

At 0C (32F) over 5 days, I started at 80% and ended up at 68%.

Vin

 

[ngogas]

@Vintre I think you almost got the question. Let me reword this....

If the temp is 20 degrees f. The battery is charged to 80 percent. Will the rate of discharge at this temperature at this charge % be more/less/equal compared to 20 degrees f at 40 percent battery charge. Assuming speed and distance driven are exactly the same.

 

[Stretch2727]

@Vintre I think you almost got the question. Let me reword this....

If the temp is 20 degrees f. The battery is charged to 80 percent. Will the rate of discharge at this temperature at this charge % be more/less/equal compared to 20 degrees f at 40 percent battery charge. Assuming speed and distance driven are exactly the same.

Yes, energy is energy. The consumption and discharge is the same at 80% or 40%. The starting point does not matter. Some may argue there is less consumption at 40% than 80% as the battery pack peak output is lower. Also, There maybe some protections that kick in at lower state of charge <20%. But, in general the consumption is the same regardless of state of charge.

That said, at 20 degrees F the car will consume more so better to have a higher state of charge to leave yourself more margin in case the car consumes more than you expect or you have an unexpected diversion.

 

[SageBrush]

[Let me reword this....

If the temp is 20 degrees f. The battery is charged to 80 percent. Will the rate of discharge at this temperature at this charge % be more/less/equal compared to 20 degrees f at 40 percent battery charge. Assuming speed and distance driven are exactly the same.

The power will be the same but the SoC will drop faster at the lower temperature at the same energy/mile consumption.
Why ? At lower temperatures the battery capacity drops.

To use a well-worn and somewhat useful metaphor from the age of petrol: at lower temperatures the tank size shrinks. A cold and full tank is still 100% full but it has less available energy.

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Aside: degradaton is not a word, degradation is. However for this discussion there is no degradation.