NMC -vs- LFP Batteries

[Tom Sawyer]

Thanks for posting these informative videos. It’s very helpful to understand the chemistry behind EV charging practices. In practical terms, the key takeaways are:

• performing 2 separate charge sessions over a couple of days, each consuming 30 kWh each is way better than a single charge consuming 60 kWh.
• Even better, performing 3 separate charge sessions over a few days, each consuming 20 kWh each is way better than a single charge consuming 60 kWh.
• Don’t store your EV at a high SOC % in hot climates

Finally, in an interview Musk explained why it takes so long to charge from 80% to 100%. Sometimes as long as charging from 20 to 80%. His answer (we can ALL relate to this):

You need to equate the charged particles (ions) to a car trying finding a space in a crowded parking lot. As the parking lot fills up, you need to drive around the lot more times to find an open space, often passing the same areas multiple times. You keep driving around hoping someone pulled out, and then you get there and another car (ion) beat you to it! 🙁

Actually there’s more to it than that. Dr. Dahn seems to focus more on state of charge (expressed as SOC for us who are still learning abbreviations) than charge rate. His takeaway for lithium nickel manganese cobalt oxides is the lower the SOC, the better.
His presentation focuses on the NMC chemistry.

 

[KevinRS]

Part of what complicates these calculations is you do not know how much reserve the manufacturer has set. They are mandated to cover the battery to still have a certain % of original charge capacity at 8 or 10 years, so after testing, they set the 100% you see at something less than the cells 100% capability, and set 0% higher than zero. Recent info seems to indicate that even for people charging to 100%, they are seeing little degradation on later generation EVs.
If a manufacturer sets 100 to 80, and zero to 20, and you keep it between the indicated 20-80, you might end up actually only using 36-64% for little gain in lifetime at all.

We will have to see what Slate's recommendations are when they release final specs.

 

[ezjob]

If the recommended charging and discharging is from 20 to 80% this will definitely hinder my buying decision especially on a 150 mile battery.

 

[phidauex]

Part of what complicates these calculations is you do not know how much reserve the manufacturer has set. They are mandated to cover the battery to still have a certain % of original charge capacity at 8 or 10 years, so after testing, they set the 100% you see at something less than the cells 100% capability, and set 0% higher than zero. Recent info seems to indicate that even for people charging to 100%, they are seeing little degradation on later generation EVs.
If a manufacturer sets 100 to 80, and zero to 20, and you keep it between the indicated 20-80, you might end up actually only using 36-64% for little gain in lifetime at all.

We will have to see what Slate's recommendations are when they release final specs.

The MachE, on release, set the SOC range to about 5% to 96%, and that was considered conservative at the time. There is indication that a future update moved that out to 97%, but I haven't confirmed that with my own measurements. No one will set their range to 20%-80%, that simply isn't needed.

The advice for charging will probably be something vague like, "charge to 80% for daily trips, and to 100% as needed for longer trips". No one should be worried about only having access to 60% of the battery they paid for - that is just FUD.

 

[AZFox]

If the recommended charging and discharging is from 20 to 80% this will definitely hinder my buying decision especially on a 150 mile battery.

I originally had a similar opinion.
Now I've looked into it more, and learned a lot from experienced members here who are EV owners. I've determined that, for me, that issue is a nothingburger.

YMMV is especially applicable here.
I intend to use the Slate for purposes it's well-suited for (mostly urban runabout duties). I can charge at home, and I have an ICEV available.

FWIW, My Likely Battery Choice swung all the way from "probably Extended" to "definitely Standard". Vote in the poll and have a look at this thread:
🔋 The Extended Battery Decision (Poll: Which battery option suits you best?)

 

[ezjob]

My problem is that I am very limited to Super Chargers or any chargers for that matter. I'm in North MS and Tupelo is 35 miles from me. It only has a few charging stations.

When I travel up into North Ms close to TN line there are even less chargers available. I'd like to take road trips in this truck without running out of power.

 

[phidauex]

My problem is that I am very limited to Super Chargers or any chargers for that matter. I'm in North MS and Tupelo is 35 miles from me. It only has a few charging stations.

When I travel up into North Ms close to TN line there are even less chargers available. I'd like to take road trips in this truck without running out of power.

Play around with https://abetterrouteplanner.com/ - they have basic specs for the Slate loaded already so you can select it as a vehicle, and choose standard or extended range. Just plot the trips you'd like to do, set some options like what SOC you'll depart home with, and what minimum SOC you'd like to arrive with, and it will show you the choices. Very powerful app, and I find it is quite accurate, and slightly on the conservative side (which is what you want).

 

[KevinRS]

The MachE, on release, set the SOC range to about 5% to 96%, and that was considered conservative at the time. There is indication that a future update moved that out to 97%, but I haven't confirmed that with my own measurements. No one will set their range to 20%-80%, that simply isn't needed.

The advice for charging will probably be something vague like, "charge to 80% for daily trips, and to 100% as needed for longer trips". No one should be worried about only having access to 60% of the battery they paid for - that is just FUD.

Not what I meant at all. You paid for the range the manufacturer stated. If there is a hidden reserve to ensure the battery lasts the warrantee period, it isn't part of the range you bought.
Recent studies have been finding that in real world conditions, recent generations of EVs are seeing very little range reduction even if charged to 100% regularly. The very early ones were a different story, but battery construction, management and temperature control have improved.

 

[Tom Sawyer]

My problem is that I am very limited to Super Chargers or any chargers for that matter.

What would hinder your charging at home or work?

Slate.auto: Charging

GOT AN OUTLET? YOU CAN CHARGE.
Many people think you need to install special equipment to charge an EV at home. We’re here to tell you: if you can charge your phone, you can charge a Slate. So, if you’re new to EVs and it seems a little, well, technical, we got you.

 

[metroshot]

The MachE, on release, set the SOC range to about 5% to 96%, and that was considered conservative at the time. There is indication that a future update moved that out to 97%, but I haven't confirmed that with my own measurements. No one will set their range to 20%-80%, that simply isn't needed.

The advice for charging will probably be something vague like, "charge to 80% for daily trips, and to 100% as needed for longer trips". No one should be worried about only having access to 60% of the battery they paid for - that is just FUD.

Never believed in undercharging.

Always charge to 100% no matter L2 at home or DCFC at Tesla Superchargers.

Since there's a buffer so that you never can reach true 100%, charging to "100%" is actually 96%.

Not worried at all since there's a 8 year HV battery warranty which I will never get to.....

 

[KevinRS]

Never believed in undercharging.

Always charge to 100% no matter L2 at home or DCFC at Tesla Superchargers.

Since there's a buffer so that you never can reach true 100%, charging to "100%" is actually 96%.

Not worried at all since there's a 8 year HV battery warranty which I will never get to.....

Exactly, and the manufacturers calibrate that buffer to make that warranty work. In California the requirement is now 10 years/150k miles for 70% range. So most manufacturers are going to build to that standard.

 

[metroshot]

Exactly, and the manufacturers calibrate that buffer to make that warranty work. In California the requirement is now 10 years/150k miles for 70% range. So most manufacturers are going to build to that standard.

That's correct - 10 years in CA.
My 2018 PHEV has a 10 year HV battery warranty and it's still going strong after 8 years.
Hoping it makes 2 more years.....

 

[ezjob]

What would hinder your charging at home or work?

Slate.auto: Charging

Charging at home is fine. It’s the road trips up hwy 25 that worries me. There are no chargers along that highway from Amory, MS North to TN.
Does the Slate come with a 240v plug for home? What about a 240v wall outlet?

 

[phidauex]

Not what I meant at all. You paid for the range the manufacturer stated. If there is a hidden reserve to ensure the battery lasts the warrantee period, it isn't part of the range you bought.
Recent studies have been finding that in real world conditions, recent generations of EVs are seeing very little range reduction even if charged to 100% regularly. The very early ones were a different story, but battery construction, management and temperature control have improved.

Apologies, my bolded statement was more for ezjob's concern about having to restrict charging - he won't need to do that. You are right that the reserves/overbuilds are standard, I just mean that a reserve of more than 10% would be very unlikely. There is a minimum reserve as well - about 2% each on the top and bottom end, to prevent low voltage disconnect, and prevent needing to change to constant voltage charging to push all the way to chemical 100%.

On stationary/grid energy storage systems we often use initial overbuilds of 30-40%, but that is for systems pushing 7000-9000 cycles over a 25 year period, the equivalent of around 2 million miles on an EV.

It has been good to see the reports and research coming out - the battery manufacturers were (generally) conservative in their estimates and it is paying off in the form of batteries performing very well compared to their promises. My MachE is at just over 50k miles and 5 years, and is at 91.5% State of Health.

 

[beatle]

Charging at home is fine. It’s the road trips up hwy 25 that worries me. There are no chargers along that highway from Amory, MS North to TN.
Does the Slate come with a 240v plug for home? What about a 240v wall outlet?

Based on their low price strategy, I really doubt Slate will include an EVSE with the truck. A lot of manufacturers are no longer providing them with new vehicles, including Tesla and Rivian. There are now a lot of relatively inexpensive 3rd party EVSEs to use with 120v and 240v receptacles (Tesla's UMC is the best and most flexible, IMO) and many people have already installed hardwired EVSEs at home.

If you haven't already, take @phidauex's advice and plan a trip using ABRP. It will likely take you on a different road that has charging infrastructure.