Lithium Plating Question

[SageBrush]

I've decided to take prophylactic steps to reduce plating in the winter if it is doable within my limitations. This question comes to mind:

If my L2 charging rate is constant, will the starting SoC affect charging ? By how much ?
I'm trying to decide whether to shift my usual 40% SoC use to the right in the winter. Say, instead of 35-75%, use 45-85% SoC

 

[camalaio]

It's easier on yourself if you don't worry about this. I do state this as someone that worries about this though

Max of 75% would probably be better than 85%, without knowing the exact makeup of Model 3 cells. Dropping to 0% is one of the worst things you can do though, so just take steps to ensure that utilizing the lower end of capacity doesn't result in you falling off the end at any point.

L2 charging rates are sufficiently slow compared to the battery capacity that questions of temperature, etc. aren't the primary factors anymore when you're talking about charging from 35% vs. 45%, only the effects of the beginning and ending charge state. Of course, I'm also not a battery chemist so take my words with a grain of lithium salt.

 

[SageBrush]

I've decided to take prophylactic steps to reduce plating in the winter if it is doable within my limitations. This question comes to mind:

If my L2 charging rate is constant, will the starting SoC affect xxx plating ? By how much ?
I'm trying to decide whether to shift my usual 40% SoC use to the right in the winter. Say, instead of 35-75%, use 45-85% SoC

Sorry, OP corrected

 

[camalaio]

Sorry, OP corrected

Ah, ok. You'll be better off shifting towards the low end, regardless of whether or not it's winter. Keep in mind if you drop below 20% the car will start dropping features that take standby power though.

Also, don't worry about plating specifically. It's counter-productive, as there are many complex processes and interactions in a lithium ion cell. Plating is one of very many. Keep to general battery health guidelines (e.g. use between 30-80%, lower top end is better, long term storage around 65% IIRC, use DC fast charging only when necessary) and you'll be just fine.

 

[SageBrush]

I do state this as someone that worries about this though

Yes, I think it was you who is to blame

Just kidding, I want to thank you for spurring me to read about the topic. It has prompted me to only charge at home at the end of a drive in the winter.

I'm still not sure how to handle those days when I want the car at 100% SoC and pre-heated in the early morning. What is the battery energy flow during pre-heating if the car is attached to the EVSE ?

 

[JohnSnowNW]

FWIW, we have not changed our charging procedure seasonally. Our Model X averages usage between 35-80% with a constant charge rate of about 26A.

Our 80% has fallen to 202 miles from a high of 207, over 2 years and 23k miles. Winters here are a bit more brutal than NM.

I realize this is a small data point...and I'd be interested to hear any "expert" opinion on any procedure that could potentially minimize plating.

 

[camalaio]

Yes, I think it was you who is to blame

Just kidding, I want to thank you for spurring me to read about the topic. It has prompted me to only charge at home at the end of a drive in the winter.

I'm still not sure how to handle those days when I want the car at 100% SoC and pre-heated in the early morning. What is the battery energy flow during pre-heating if the car is attached to the EVSE ?

The car will pull whatever it needs from the EVSE for pre-heating, and leftover power is used to charge the battery (if it is not yet charged). If it's already charged to the limit you set, then it's simply only pulling power for the heat.

The upcoming (or is it here? away from my car for a while) feature of scheduling a departure time is useful here. It aims to finish charging and preheat your cabin just before the time you set to leave. This is the absolute best thing you can do, minimising waste power and being at 100% for as little time as possible. Without the feature, you have to guess based on what the car says for time remaining and schedule the charge appropriately.

 

[SageBrush]

Winters here are a bit more brutal than NM

trivia: NM has mountains. The tail end of the Rockies, for the most part.
We do not tend to mention this on open forums because it interferes with the Hot Chile message

I share your sentiment. I want my Model 3 to be the last car I buy, so I'm always on the lookout for that extra edge.

 

[SageBrush]

About the chemistry of plating (thinking aloud here ... no expertise involved):
At a higher SoC more Li ions will be nicely intercalated into the anode and cell potential will be higher. The net charging potential will then be lower and the ion flow concentration and therefore ion cloud aroun the anode. reduced.

Or so I imagine. Poppycock ?

 

[Uncle Paul]

I would imaging that varying your charging techniques from time to time, would also help in extending battery life.

 

[insaneoctane]

I've read a lot about high temperature and high SOC being the enemy.... But I haven't read much on low SOC being bad. Someone willing to point me to a few good references for this information? BTW I am not refuting it, just interested...

 

[5_+JqckQttqck]

Can't find the graph but summer 20-60/70 is optimal. Colder months 20-80/90 is optimal. Less than 10% and above 90% = the worse for plating.

Here's some reading if you're interested.

https://www.nrel.gov/docs/fy18osti/70616.pdf

 

[gecko10x]

I've read a lot about high temperature and high SOC being the enemy.... But I haven't read much on low SOC being bad. Someone willing to point me to a few good references for this information? BTW I am not refuting it, just interested...

You might find this post interesting:
Battery Degradation Scientifically Explained

I didn't read the linked article, but I think it says that stress cracks are introduced above 60% SOC, and they heal when the stress is lowered by being at a low SOC.

 

[KenC]

trivia: NM has mountains. The tail end of the Rockies, for the most part.
We do not tend to mention this on open forums because it interferes with the Hot Chile message

I share your sentiment. I want my Model 3 to be the last car I buy, so I'm always on the lookout for that extra edge.

Well, skiers love to hear about Taos and Al's Run, so not everyone worries about the Hot Chile message.