Tech talk about NMC cell chemistry and charging parameters

[Benjamin Nead]

The battery packs in the Slate EV Truck will come with the lithium ion cell formulation known as NMC, or Nickel Manganese Cobalt. I've noticed conversations here on the Slate Forums in more than one thread regarding the assets and limitations of NMC. There is debate over whether EVs with this cell chemistry should strictly adhere to a charge/discharge cycling regime of 80% to 20% or not. It's probably prudent to start a dedicated thread here for just that topic.

I'll start with the Wkipedia page titled Lithium Nickel Manganese Cobalt Oxides . . .

https://en.wikipedia.org/wiki/Lithium_nickel_manganese_cobalt_oxides

Next is a YouTube video from the Engineering Explained YouTube channel with host Jason Fenske. This is one of the best overviews on NMC I've seen, taken down to a molecular level of what exactly is going on inside the cell pouch during charging, discharging, storing and use. How does heat or cold effect the performance and longevity? And, yeah, that whole 80 to 20 percent thing. It's a quick paced talk with a lot of information that's worth coming back to for successive viewing . . .



Jason references the work of Jeffery Dahn a couple of times in his video. Dr. Dahn of Dalhousie University in Halifax, Canada, might be the most knowledgeable living authority on NMC cell chemistry. Linked in the Engineering Explained video notes is this one: an hour long discussion with Dr. Dahn on EV Battery Health . . .



And this article from The Korea Economic Daily outlines the business relationship between Korean cell Manufacturer SK On and Slate . . .

https://www.kedglobal.com/batteries/newsView/ked202504250003

Have fun!

 

[Imhotep]

This is great information for an EV noob like me. Feeling better about using level 1 charging for the 20 miles I usually travel per day. Thanks for posting!

 

[GaRailroader]

With respect to the 80/20 rule, that is what I follow with our Tesla Model 3 for daily driving needs. On my 150 mile range Nissan Leaf, I charge 100% every time. Nissan doesn’t have the same features as the Tesla for setting charge limit. If I only wanted to charge it 80% I would have to figure out how long it would take to get to that level and set the charging time to cut off at that time. I wonder if Nissan is just limiting user access to the full battery so that when I charge it from 0 miles to 150 miles I am really charging it from 10% to 90% or something like that.

 

[GaRailroader]

In this article they are indicating the small pack has a 47 kWh net capacity versus the 53 kWh gross capacity cited everywhere else. I wonder if they will not be doing the 80/20 thing and giving you full access to the 47 kWh usable and use the leftover 6 kWh for the 80/20 longevity protection. If this theory is correct and we can get 150 miles out of the 47 kWh usable then the efficiency ends up being 3.2 miles/kWh instead of the 2.8.

https://www.caranddriver.com/news/a64564869/2027-slate-truck-revealed/

 

[Benjamin Nead]

In this article they are indicating the small pack has a 47 kWh net capacity versus the 53 kWh gross capacity cited everywhere else. I wonder if they will not be doing the 80/20 thing and giving you full access to the 47 kWh usable and use the leftover 6 kWh for the 80/20 longevity protection. If this theory is correct and we can get 150 miles out of the 47 kWh usable then the efficiency ends up being 3.2 miles/kWh instead of the 2.8.

https://www.caranddriver.com/news/a64564869/2027-slate-truck-revealed/

Yeah, I can't account for that discrepancy with Car and Driver. I don't think we're really going to know the true range of the Truck until it goes through the EPA testing cycle.

One of the things I took away from the Engineering Explained and Jeffery Dahn interview videos (above) was the variations of NMC formulas. Higher nickel content may give slightly improved range, but at the expense of longevity of the cells.

 

[Neil Nelson]

Great videos. Learned a lot.