Model 3 SR+ LFP Battery Range, Degradation, etc Discussion

[AlanSubie4Life]

I.e. if the car thinks that its battery capacity is 60 kWh, and you charge from 50% to 100% at the end of your experiment and put 35 kWh (instead of 30 kWh) in, then that suggests that the BMS has gotten off by 5 kWh.

There’s nothing in the car that allows you to measure this. There is just the kWh added number, which is just the number of miles added * the Wh/mi constant. And even that formula is incorrect if you’re above the degradation threshold!

In short, the kWh on the screen is not a good measure of how many kWh were added to the battery. Close, usually, but won’t be helpful for this purpose. You can just look at how many miles were added and that is completely equivalent, even if the BMS was super confused and the actual amount of energy added was far different than what it displays (due to BMS drift that it figures out/resolves on the 100% charge).

I know, pretty confusing.

Pretty much all you can do in this case is see how much your predicted 100% charge shifts (and try to minimize the potentially large error on that extrapolation if not using SMT), and compare to the actual 100% charge value.

 

[MRT336]

Quick question about charging on these LFP batteries. I just took delivery of a 2022 M3 SR+ with the LFP battery. I understand that EV batteries take longer to charge as they get to the top percentage of the battery capacity, but does charging them regularly to 100% also use more energy? In other words, does charging from 80-100% use the same amount of electricity as charging from 40-60%? I'm trying to determine if there is any downside to keeping it charged to 100% all the time.

 

[AlanSubie4Life]

Quick question about charging on these LFP batteries. I just took delivery of a 2022 M3 SR+ with the LFP battery. I understand that EV batteries take longer to charge as they get to the top percentage of the battery capacity, but does charging them regularly to 100% also use more energy? In other words, does charging from 80-100% use the same amount of electricity as charging from 40-60%? I'm trying to determine if there is any downside to keeping it charged to 100% all the time.

There’s a tiny difference at the very top in the taper in some vehicle types but it’s pretty negligible. If you use 7.7kW charging it is “more noticeable.” So small it is not worth worrying about. If you have a wall meter you can roughly see when the rate starts to drop off. At 7.7kW it might not happen until close to 100%. Additionally I think the LFPs accept more charge current at 100% (limited regen not much of an issue with these batteries) so it may be that it makes no practical difference at all for LFP.

But you are right that you want maximum charge rate to minimize charging overhead. So use 7.7kW (32A @ 240V) and I would say don’t worry about this issue. In any case you can measure it yourself.

 

[3sr+buyer]

Quick question about charging on these LFP batteries. I just took delivery of a 2022 M3 SR+ with the LFP battery. I understand that EV batteries take longer to charge as they get to the top percentage of the battery capacity,

The top taper should be minimal with typical AC charging at home at around 7kW. It is more noticeable with DC fast charging (Supercharging for Teslas) which can have peak charging rates that are much higher than 7kW but is not much faster than typical AC charging near 100%.

 

[thebestiam1]

2021 Model 3 w/ LFP / 980 Motor checking in. 100% is showing 246 miles. Is that normal? Also it it bad to charge to 100% everyday?

 

[Baluchi]

2021 Model 3 w/ LFP / 980 Motor checking in. 100% is showing 246 miles. Is that normal? Also it it bad to charge to 100% everyday?

Mine is at 246 too, which seems reasonable.

Might want to look back through the thread, because I think the 100 percent thing has been discussed at length.

 

[Cassady Brewer]

So probably a stupid question but is the LFP battery only on the Model 3 and not the Long Range and Performance?

 

[RichAZ/CapeCod]

So probably a stupid question but is the LFP battery only on the Model 3 and not the Long Range and Performance?

Correct.

 

[Cassady Brewer]

Ok thanks appreciate it! I didn’t know that.

 

[3sr+buyer]

So probably a stupid question but is the LFP battery only on the Model 3 and not the Long Range and Performance?

Yes, in the US, the following Model 3 come with LFP batteries:

• Some late 2021 Standard Range Plus (with 253 mile EPA range). (Most 2021 Standard Range Plus have NCA batteries (263 mile EPA range).)
• 2022 Rear Wheel Drive (with 272 mile EPA range).

 

[TexaCali]

And while we are on LFP basics, it is worth re-iterating that LFP batteries are much less prone to fires than other chemistries currently in use. I've seen a few news reports of Tesla fires recently (newsworthy because they are rare), but none have been LFP vehicles.

Remember, the only stupid question is the one you fail to ask (because you were worried it might be stupid).

 

[3sr+buyer]

And while we are on LFP basics, it is worth re-iterating that LFP batteries are much less prone to fires than other chemistries currently in use.

Yes, fire risk of battery chemistries: LMO < LFP << NMC < NCA.

However, LMO and LFP have lower energy density (i.e. batteries are bigger and heavier for the same capacity). LMO also has poor longevity, the opposite of LFP's good longevity. LMO was used in early Nissan Leaf (they don't catch fire, but they also degrade quickly -- probably made worse by the lack of liquid cooling in the Leaf).

With the relatively flammable NCA chemistry, something beyond depending on quality control at the battery supplier was needed, due to the large number of cells in each pack. Hitting the Books: How Tesla engineers solved the problem of exploding EV batteries | Engadget describes some of what Tesla was thinking in the early days, and some of the fire mitigation design so that a failed cell is less likely to cause the entire pack to catch fire.

Teslas do have a very low rate of fires, mostly due to crash damage, but there was some recent news of a Model Y catching fire while driving and not crashing.

 

[AlanSubie4Life]

Teslas do have a very low rate of fires, mostly due to crash damage, but there was some recent news of a Model Y catching fire while driving and not crashing.

A bit off topic, but just a comment: If it was the one near the construction site or whatever it was, that one looked like it was a cabin fire, it didn't have the appearance of starting from the pack. That's a second fire of that type (there was the recent parked one recently reported, which also could have been arson). Obviously those types of cabin fires could be something like the PCS catching on fire or some other high current electronics and thus be an issue with the vehicle, but it could also be consumer electronics in the cabin (lithium batteries!) catching fire due to malfunction (happens quite a lot).

 

[username123]

I am going on a trip for one month. I am planning to leave the car plugged in inside of the garage with the slow charger that it comes with but should I leave it at 50% or 100%

 

[Ther0ck]

I am going on a trip for one month. I am planning to leave the car plugged in inside of the garage with the slow charger that it comes with but should I leave it at 50% or 100%

I would say 50% since 100% is not necessary. Charge it to 100% when you get home.

 

[amit_gunner]

I would say 50% since 100% is not necessary. Charge it to 100% when you get home.

Well i am also going away but only for a Week i am gonna leave it unplugged inside garage around 50% SOC.

 

[RichAZ/CapeCod]

Hope you guys doing the "going away and leaving it plugged in/unplugged, 100% -- 50% report back on the results.

Bet ya all a cup of coffee and a donut there will be none to be seen.

Rich

 

[AAKEE]

Well i am also going away but only for a Week i am gonna leave it unplugged inside garage around 50% SOC.

Nice, with sentry off, I guess?

 

[3sr+buyer]

I am going on a trip for one month. I am planning to leave the car plugged in inside of the garage with the slow charger that it comes with but should I leave it at 50% or 100%

For a month of storage, 50% is likely to be better for the battery than 100%, although it may not necessarily be that noticeable with an LFP battery.

Charge it back to 100% when you get back if you are concerned about the BMS losing track of the actual state of charge.

 

[TSLM3CAN]

10k update:
M3 RWD with LFP batteries
10,000 kms in 3+months.
Range dropped from 438kms to 433kms. My understanding is first 2km loss due to calibration, droped within first few weeks. So the real loss is 3 kms. Zero supersharging . Daily level 2 home charging to 100%.
So far so good