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

[AAKEE]

I had the same thought, so I ran the battery health test in service mode yesterday. The results showed battery health at 92%, but the estimated range is still 227 miles. That math doesn’t add up, right (I started at 253, so 92% should be 232)?

The health test is probably a bit too positive.

The delivered energy is dependant on the power during the discharge. Lower power makes the battery deliver more energy.

The healt test use the AC/climate (?) to discharge the battery?
Anyway it is a slower discharge than normal driving (from where the BMS calculated energy comes) so the result would by principle exaggerate the real capacity in that test.

 

[eevee-fan]

https://insideevs.com/features/718824/find-tesla-battery-degradation/

 

[AlanSubie4Life]

https://insideevs.com/features/718824/find-tesla-battery-degradation/

Would have been good for the article to quote the source, or at least also provide the reference to TMC, even if the article independently arrived at the method.

Oh well. To be clear this method was arrived at through observations with the help of @ran349 and a few others providing SMT data as a crosscheck.

 

[nicksp]

Question for the battery experts. On my 18 M3LR I see a range of 302 miles. This is a consistent number at full 100% charger. If I drive at 65 mph with manual AC etc I easily get that range.
When Tesla shows range, how do they want you to drive to get that range?

 

[gt2690b]

Question for the battery experts. On my 18 M3LR I see a range of 302 miles. This is a consistent number at full 100% charger. If I drive at 65 mph with manual AC etc I easily get that range.
When Tesla shows range, how do they want you to drive to get that range?

i feel like you just answered your own question

 

[AlanSubie4Life]

Question for the battery experts. On my 18 M3LR I see a range of 302 miles. This is a consistent number at full 100% charger. If I drive at 65 mph with manual AC etc I easily get that range.
When Tesla shows range, how do they want you to drive to get that range?

On the Model 3 LR RWD 2018, they want you to get 223Wh/mi to 224 Wh/mi. (Not 234Wh/mi)

 

[nicksp]

On the Model 3 LR RWD 2018, they want you to get 223Wh/mi to 224 Wh/mi. (Not 234Wh/mi)

Why did you specifically mention not 234 Wh/mi?

 

[nicksp]

i feel like you just answered your own question

I guess I did but just wanted to see what else some more experienced users could add.

 

[AlanSubie4Life]

Why did you specifically mention not 234 Wh/mi?

That is the vehicle constant 76kWh/325mi. Started at ~78kWh. Rated line for that vehicle is 239Wh/mi ,which means 234Wh/mi. (Line is 5Wh/mi high by design.)

95.5% of that 234Wh/mi is the number I gave.

 

[kaimanson]

I just charged mine up to 100% today — 236 miles. Same age, same battery capacity, but less than 17,000 miles on the car…

It keeps letting think that battery degradation is more about time than super charging, cycles, or miles driven.

 

[eevee-fan]

Correction:
LFP not immune to higher degradation at 100%. Better than NMC but still higher degradation.

 

[JuanF1]

LFP degrade at 100% more than NMC!

That is not what is being said !

The following is mentioned (around minute 40):
- You don't want to keep you battery plugged in at 100% for long duration --> but this is valid for any battery technology
- We should not worry too much, since, in general, LFP is good from a lifetime point of view.

 

[DuncanM]

Correction:
LFP not immune to higher degradation at 100%. Better than NMC but still higher degradation.

He states that there is a top buffer so 100% indicated SOC is actually about 95% true SOC and while holding the battery at a true 100% for many days in high temperatures would be problematic, charging to 100% briefly is not, and is required to balance the cells and give the BMS an accurate indication of true SOC.

 

[AAKEE]

He states that there is a top buffer so 100% indicated SOC is actually about 95% true SOC and while holding the battery at a true 100% for many days in high temperatures would be problematic, charging to 100% briefly is not, and is required to balance the cells and give the BMS an accurate indication of true SOC.

For what car?

I would say that Tesla do not use top buffers on their LFP's

 

[eevee-fan]

When at home, I do not charge to 100%, regardless of how long. I do charge to 100% before I go on road trips and also during (hotel charging, long stretches where I do need 100%).

 

[DuncanM]

For what car?

I would say that Tesla do not use top buffers on their LFP's

You can hear his statements starting at 37:50.

 

[yesimon]

He states that there is a top buffer so 100% indicated SOC is actually about 95% true SOC

At that segment he is talking mostly about home/commercial batteries and specifically referring to his own home battery which is limited to ~95%.

 

[karlos22]

There must be some sort of top buffer for the LFP as there is still a lot of regen when the battery is fully charged.

The actual amount I do not know, but clearly if it was 100% true SOC there would be zero regen.

 

[eevee-fan]

There must be some sort of top buffer for the LFP as there is still a lot of regen when the battery is fully charged.

The actual amount I do not know, but clearly if it was 100% true SOC there would be zero regen.

Regen is not battery capacity dependent, it is BMS dependent. Agree that 100% is not true 100% but the car can also be set to allow no regen above 90%. See case of Powerwall that will no charge battery until down to 60%. It is all software.

 

[Bouba]

There must be some sort of top buffer for the LFP as there is still a lot of regen when the battery is fully charged.

The actual amount I do not know, but clearly if it was 100% true SOC there would be zero regen.

Do you have that option where the brakes are applied to mimic regen ?