Losing Mileage per 80% Charge over Time

[henchman24]

Extremes of hot and cold are not great on batteries, where the cutoffs are depends a lot of the specific chemistries... and what is specifically happening. For charging, you want batteries hot... >105f if not nearing 130f. This drastically reduces lithium plating when charging. Cold when charging can cause major issues. But when sitting, you ideally want them between 45-70f. A hot battery sitting at high SoC will degrade very quickly (see early Leafs in Arizona). Where when sitting, a cold battery won't have any major degradation issues... they just perform worse.

Now LFP cells actually don't like to be cold. They underperform rather drastically under 45f, and charging them under 32f accelerates their degradation rather dramatically. If you get to 5f or lower, they may only get a 100 cycles out of batteries rated for 3-4000+ cycles. They are also a bit more sensitive than other chemistries at higher temps. This is partly why LFP has more issues with long charging sessions as the don't really like to be above 120-125f. When you see LFP batteries with >5C charge rates, if you look through what they are doing, they are taking a ~5000 cycle rated battery at 1C and pulling it a ~1000 cycle at >5C (some will push 7 or 9C and go for 750 cycles). Effectively killing 80% of the battery life... but since 1000 cycles is a ton anyway (similar to NMC, NCA, or NCMA), it doesn't practically matter.

The NMC chemistry in the CT is a bit of an unknown since we don't have a ton of scientific data on 955 chemistry cells. If we take what we have learned from 811 chemistry, we can expect 955 to have a narrower temperature window they like to be in. The hot charging rule still applies, but the temp it likes to be and the low temps of accepting a charge are higher. An 811 cell really shouldn't be charged below ~10f to avoid similar issues ot LFP at 32f. A 955 is probably closer to 15-20f. This is why if your battery gets cold soaked, you'll see Tesla try to warm it up prior to charging and when it starts charging it'll only trickle in a bit first.

With all of this though, outside the very extremes (Death Valley in the peak of summer or Arctic Circle in the middle of winter)... any modern EV liquid cooled pack will manage this by itself to make it fool proof.

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[bosshog]

Extremes of hot and cold are not great on batteries, where the cutoffs are depends a lot of the specific chemistries... and what is specifically happening. For charging, you want batteries hot... >105f if not nearing 130f. This drastically reduces lithium plating when charging. Cold when charging can cause major issues. But when sitting, you ideally want them between 45-70f. A hot battery sitting at high SoC will degrade very quickly (see early Leafs in Arizona). Where when sitting, a cold battery won't have any major degradation issues... they just perform worse.

Now LFP cells actually don't like to be cold. They underperform rather drastically under 45f, and charging them under 32f accelerates their degradation rather dramatically. If you get to 5f or lower, they may only get a 100 cycles out of batteries rated for 3-4000+ cycles. They are also a bit more sensitive than other chemistries at higher temps. This is partly why LFP has more issues with long charging sessions as the don't really like to be above 120-125f. When you see LFP batteries with >5C charge rates, if you look through what they are doing, they are taking a ~5000 cycle rated battery at 1C and pulling it a ~1000 cycle at >5C (some will push 7 or 9C and go for 750 cycles). Effectively killing 80% of the battery life... but since 1000 cycles is a ton anyway (similar to NMC, NCA, or NCMA), it doesn't practically matter.

The NMC chemistry in the CT is a bit of an unknown since we don't have a ton of scientific data on 955 chemistry cells. If we take what we have learned from 811 chemistry, we can expect 955 to have a narrower temperature window they like to be in. The hot charging rule still applies, but the temp it likes to be and the low temps of accepting a charge are higher. An 811 cell really shouldn't be charged below ~10f to avoid similar issues ot LFP at 32f. A 955 is probably closer to 15-20f. This is why if your battery gets cold soaked, you'll see Tesla try to warm it up prior to charging and when it starts charging it'll only trickle in a bit first.

With all of this though, outside the very extremes (Death Valley in the peak of summer or Arctic Circle in the middle of winter)... any modern EV liquid cooled pack will manage this by itself to make it fool proof.

Extremes of hot and cold are not great on batteries, where the cutoffs are depends a lot of the specific chemistries... and what is specifically happening. For charging, you want batteries hot... >105f if not nearing 130f. This drastically reduces lithium plating when charging. Cold when charging can cause major issues. But when sitting, you ideally want them between 45-70f. A hot battery sitting at high SoC will degrade very quickly (see early Leafs in Arizona). Where when sitting, a cold battery won't have any major degradation issues... they just perform worse.

Now LFP cells actually don't like to be cold. They underperform rather drastically under 45f, and charging them under 32f accelerates their degradation rather dramatically. If you get to 5f or lower, they may only get a 100 cycles out of batteries rated for 3-4000+ cycles. They are also a bit more sensitive than other chemistries at higher temps. This is partly why LFP has more issues with long charging sessions as the don't really like to be above 120-125f. When you see LFP batteries with >5C charge rates, if you look through what they are doing, they are taking a ~5000 cycle rated battery at 1C and pulling it a ~1000 cycle at >5C (some will push 7 or 9C and go for 750 cycles). Effectively killing 80% of the battery life... but since 1000 cycles is a ton anyway (similar to NMC, NCA, or NCMA), it doesn't practically matter.

The NMC chemistry in the CT is a bit of an unknown since we don't have a ton of scientific data on 955 chemistry cells. If we take what we have learned from 811 chemistry, we can expect 955 to have a narrower temperature window they like to be in. The hot charging rule still applies, but the temp it likes to be and the low temps of accepting a charge are higher. An 811 cell really shouldn't be charged below ~10f to avoid similar issues ot LFP at 32f. A 955 is probably closer to 15-20f. This is why if your battery gets cold soaked, you'll see Tesla try to warm it up prior to charging and when it starts charging it'll only trickle in a bit first.

With all of this though, outside the very extremes (Death Valley in the peak of summer or Arctic Circle in the middle of winter)... any modern EV liquid cooled pack will manage this by itself to make it fool proof.

Thanks for the advice . So based upon the above charging a battery when cold is damaging to the battery ( ie really bad ) . So with daily home charging (winter ) should I precondition the battery before charging even if it’s just a 10-20 charge that’s needed . Or will the vehicle do this precondition automatically . ( home charging )

 

[henchman24]

Thanks for the advice . So based upon the above charging a battery when cold is damaging to the battery ( ie really bad ) . So with daily home charging (winter ) should I precondition the battery before charging even if it’s just a 10-20 charge that’s needed . Or will the vehicle do this precondition automatically . ( home charging )

The vehicle will handle it. Tesla (and all automakers) design their cars so nobody should have to worry about any of this.

 

[CyberGus]

The vehicle will handle it. Tesla (and all automakers) design their cars so nobody should have to worry about any of this.

Right, charging in the cold will just be slower and use more power because it will bring the pack up to a safe temperature.

 

[Gaximus]

I think we're talking past in other in violent agreement.

Of course the calculation includes consumption based on driving style... but only for the current trip. Nothing you did yesterday should affect the drive you take today. This is where we seem to differ.

In your theory, if I tow for a week getting 150mi of range, and then head out on Monday without a trailer, the range estimate will still be based on last week's 1000Wh/mi?

It doesn't need to know how you drove last week, it is not relevant to today.

I guess an easy way to test this is to switch driver profiles sitting in the driveway, and see if that affects the range estimate. Any saved "driving style" statistics would need to be segregated by user, right?

I was thinking the same thing, about switching profiles to see, but if it goes by vehicle and not profile wouldn’t work. But your wh/ml isn’t the same as “acceleration habits”. Don’t would know if your towing a trailer or not and adjust. But I don’t think the range estimate resets everyday or every drive. Otherwise you’d take off and have a widely different estimated range and would start calculating and changing like crazy.

 

[CyberGus]

I don’t think the range estimate resets everyday or every drive.

I can find no definitive data on this point.

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