Facelift model 3 charging habits

[Basicbob]

With regards to the new facelift model what are the best practices for longevity of the battery?

On YouTube they say 20-80% but others say 10-90% on the new models. One even said charge it to 100% occasionally to calibrate the battery.

what’s the consensus for the new facelift model?

 

[nxsynjs]

I dont think it's any different to previous versions. I'm told chemically the optimum is between 50 and 70%. you can use the ranges above but it wont be best.. best but also won't matter a huge amount. Just avoid having it sit at <20% and >90% for days.

 

[Glan gluaisne]

Why should it be any different?

All EVs have a battery management system, and there's no indication that there's been any change to this for the facelift model, it still manages the battery in the same way as has always been the case.

There are very few user behaviour factors that can have even a tiny influence on battery behaviour and lifetime, like all other EV manufacturers, Tesla lock down the BMS behaviour tightly, so they can provide a long battery warranty, no matter what a user tries to do.

Constantly rapid DC charging the battery, with no lower charge rate AC charges, might cause the BMS to struggle to maintain cell group balance after a while, and may cause the BMS to limit the maximum DC charge rate, perhaps. Constantly charging the battery to 100% may have a very slight impact on cycle life and age-related degradation, and is best avoided. Same goes for constantly discharging the battery pack right down to 0% cut-off.

None of these things are very likely to happen in normal use, though, and by default the car comes set to charge to ~90%, unless over-ridden by the user. From my experience of building and running battery packs for several years now, I'd suggest that staying within the 10% to 90% SoC range ensures a good cycle life, 20% to 85% makes a very small improvement. Anything else is down in the noise, and swamped out by age related degradation.

Cycle life rarely, if ever, is the limiting factor for an EV battery pack anyway, so going to extraordinary lengths to get maybe a 10% improvement is pointless, as age-related degradation will be far greater. For example, take an EV with a 50 kWh usable capacity battery pack, that uses 250 Wh per mile, and is driven for the UK average mileage of ~8,000 miles per year. Over a year the battery pack will get cycled through the equivalent of about 40 full cycles. Cycled from 10% to 90% the cells Tesla use are probably good for between 1,000 and 2,000 cycles, so that equates to a cycle life of between 25 and 50 years. Increasing that to maybe 30 year to 60 years by slightly tweaking the way the car is used won't make a jot of difference in the real world, as age-related degradation will cause the pack to fail long before there's a cycle life issue.

 

[pdk42]

Why should it be any different?

All EVs have a battery management system, and there's no indication that there's been any change to this for the facelift model, it still manages the battery in the same way as has always been the case.

There are very few user behaviour factors that can have even a tiny influence on battery behaviour and lifetime, like all other EV manufacturers, Tesla lock down the BMS behaviour tightly, so they can provide a long battery warranty, no matter what a user tries to do.

Constantly rapid DC charging the battery, with no lower charge rate AC charges, might cause the BMS to struggle to maintain cell group balance after a while, and may cause the BMS to limit the maximum DC charge rate, perhaps. Constantly charging the battery to 100% may have a very slight impact on cycle life and age-related degradation, and is best avoided. Same goes for constantly discharging the battery pack right down to 0% cut-off.

None of these things are very likely to happen in normal use, though, and by default the car comes set to charge to ~90%, unless over-ridden by the user. From my experience of building and running battery packs for several years now, I'd suggest that staying within the 10% to 90% SoC range ensures a good cycle life, 20% to 85% makes a very small improvement. Anything else is down in the noise, and swamped out by age related degradation.

Cycle life rarely, if ever, is the limiting factor for an EV battery pack anyway, so going to extraordinary lengths to get maybe a 10% improvement is pointless, as age-related degradation will be far greater. For example, take an EV with a 50 kWh usable capacity battery pack, that uses 250 Wh per mile, and is driven for the UK average mileage of ~8,000 miles per year. Over a year the battery pack will get cycled through the equivalent of about 40 full cycles. Cycled from 10% to 90% the cells Tesla use are probably good for between 1,000 and 2,000 cycles, so that equates to a cycle life of between 25 and 50 years. Increasing that to maybe 30 year to 60 years by slightly tweaking the way the car is used won't make a jot of difference in the real world, as age-related degradation will cause the pack to fail long before there's a cycle life issue.

This paper seems to indicate that cycle degradation is still the dominant factor compared to time degradation:

As expected, the capacity loss of the cycle-life aged cells was higher than that of the calendar-life aged cells. However, the measurable capacity loss for the calendar-life aged cells indicates continued immobilization of Li+ ions. Furthermore, electrolytes extracted from the calendar-life aged cells showed more LiPF6 hydrolysis products than those extracted from the cycle-life aged cells. We discuss possible mechanistic causes for the observed aging behaviors in this article.

Calendar-life versus cycle-life aging of lithium-ion cells with silicon-graphite composite electrodes (Journal Article) | OSTI.GOV

 

[Glan gluaisne]

This paper seems to indicate that cycle degradation is still the dominant factor compared to time degradation:




Calendar-life versus cycle-life aging of lithium-ion cells with silicon-graphite composite electrodes (Journal Article) | OSTI.GOV

My experience of building packs with various chemistry cells suggests that under real-world operating conditions this isn't the case. It also varies a very great deal between different chemistry cells. For example, about ten years ago or so I did some tests on cycling some relatively new LFP cells. They had about a 20% degradation after 8000 cycles run from 10% to 90%. At the same time, I tested some NCA cells (virtually identical to early Tesla 18650s) and they had a 20% degradation over the same cyclic charge/discharge range of about 650 cycles.

Since then, cell chemistry seems to have come on in leaps and bounds, with both cycle life and age related degradation being improved. The first through really quite subtle changes in chemistry, almost all of the latter coming from cleaner and better controlled production techniques.

 

[Durzel]

I typically leave my charge limit on 50% if I'm not going anywhere, but it's not always plugged in.

The only consensus seems to be not to charge it to 100% and just leave it like that. Everything else is, to a greater or lesser extent, speculation.

It's easy to get a bit obsessive about this stuff, and get lost down a rabbit hole of "where's my missing miles!" etc, but at the end of the day the battery has a 8 year warranty. If when it actually gets to the point where it's behaving abnormally, and easily provable, then that would be the time to be doing service requests, etc.