2022 LFP Model 3 - Best method of Charging ?

[mrluke]

So picked up my Model 3 in December , and currently still on my 17p per KW tarriff until Jan 31st,

On the 31st im moving over to BritishGas EV Tarriff , so charging from 12am to 5.30am @ 12p a KW.

I currently do 60 miles a day and charging up on Sunday,Tuesday and Thursday .

Currently in winter im using between 40-55% per 2 days, so im charging it upto 100% every time. I calculated i should most of the time be able to get back to 100% in the allocated hours using the cheaper 12p a kw providing i charge every 2 days.

Would any one be able to answer these questions.

> They say charging LFP batterys to 100% each time is the way to go, does it use a lot more electricty getting from say 90% to 100% ? More cost effective to only charge to say 90% or 80%.

> Is only running my batterys down to 50% most of the time bad ? should i be going lower to like 30/20% ?

> Whats the best way for setting a charge schedule ?, Via the Tesla or via the Gen3 Tesla charger.

I plan to keep this car for quite a long time so ideally want to treat it as nice as possible.

Thanks !

 

[qwickshot]

If you are using the car daily, I really wouldn’t think about it, just plug it when it’s parked and charge it when you need it. Job jobbed.

The only thing I would say is that I would avoid charging it to 100% if you know you are not going to use it the following day. I don’t use my car to commute so leaving it pinned at 100% 5 days a week is not the best idea.

Yes LFP should be charged to 100% regularly to help calibrate the BMS and it’s a more stable chemistry. But leaving it at 100% for long periods will still degrade the battery faster than it other wise would do.

 

[Astrape]

> They say charging LFP batterys to 100% each time is the way to go, does it use a lot more electricty getting from say 90% to 100% ? More cost effective to only charge to say 90% or 80%.

Teslafi gives you its estimate of efficiency of each charge. If you like this level of detailed data you may want to try it. You get a months free trial with the referral code.

Teslafi tells me charging efficiency is generally 95/96% efficient on my 7kW home charger at current temperatures. The last 5-10% goes a lot slower and the efficiency varies in the 80-95% region. If you start from a higher percentage SOC the efficiency is lower because the battery has not already been warmed by taking charge. In your case the efficiency will perhaps be more likely >90% for the last trickle charge.

> Is only running my batterys down to 50% most of the time bad ? should i be going lower to like 30/20% ?

LFP batteries dont suffer from battery memory in the Tesla with its excellent battery management. So the low level is not important.

As for all battery chemistries running in the 20-80% region or 10-90 will give slightly better battery condition in the long term. However there are two counterpoints. One is that Tesla recommends charging to 100%. This is due to the difficulty of calibrating the charge level against the voltage in an LFP battery. In cold weather the first LFPs were finding 20-30% charge disappearing during journeys due to SOC errors. Since its critically important to know your state of charge correctly Tesla started to recommend 100% charging. The second point is that from a battery lifetime this is not optimal, however the life of the LFP battery is so long 500k miles+ that this probably doesnt matter in the real world.

Personally bing a fussy engineer I charge to 90% most of the time and 100% once a fortnight. But it probably doesnt make a meaningful difference to battery degradation. LFP degradation is really low compared yo the cadmium batteries. We’ll see in a few years time!

The Puzzling Reason Why Tesla Misleadingly Recommends Charging the LFP Batteries to 100%

When Tesla started deliveries of the Model 3 RWD with lithium ferrophosphate (LFP) batteries, it made a strange recommendation on its website and in the ...

www.autoevolution.com

> Whats the best way for setting a charge schedule ?, Via the Tesla or via the Gen3 Tesla charger

I presume either scheduling will work fine. Would the charger resume after a power cut?

For my charger scheduling in the car allows it to resume after our regular power loss (live in a forest).

I plan to keep this car for quite a long time so ideally want to treat it as nice as possible.

Thanks !

 

[thewishy]

If you are using the car daily, I really wouldn’t think about it, just plug it when it’s parked and charge it when you need it. Job jobbed.

The only thing I would say is that I would avoid charging it to 100% if you know you are not going to use it the following day. I don’t use my car to commute so leaving it pinned at 100% 5 days a week is not the best idea.

Yes LFP should be charged to 100% regularly to help calibrate the BMS and it’s a more stable chemistry. But leaving it at 100% for long periods will still degrade the battery faster than it other wise would do.

This is supposedly not the case for LFP, as the cell voltage is a little lower than NCA.

Charging to 100% means you're not going to get regen for a portion of the next journey. I'd suggest you charge to 80% most of the week, then one night a week charge to 100%

 

[Astrape]

Why in the long term battery degradation will be so much less of an issue in LFP batteries:

>90% capacity at 500-1000k miles!

 

[qwickshot]

Those tests will be based on cycling the battery. The clue in the graph is ‘equivalent’, so what that means they are cycling the battery from a fixed % to a fixed % (E.g. 20% to 70%) and not full to empty. They then correct the cycle count based on the % charged/discharge, the above example would be 0.5 cycles.

The above will not apply if the cell has been stored at 100% capacity for long periods of time as that causes battery aging that can not be measured via cycling the battery and takes a long time because you cant artificially speed it up.

There is a huge thread about LFP batteries in this thread with contributions from people who actually work with them.

So yes, they last a lot longer but that doesn’t mean things like storing them at 100% for long periods of time do not cause degradation.

You have to remember your battery warranty is 70% degustation at 8 years. It’s set at that level so they don’t have to change any due to degradation of cars are usually abused. But on a 60 kWh battery, the difference between 90% and say 85% after 10 years is significant because you don’t have loads spare to start with.

That said, if you are just going to keep the car for 3-4 years, it will not be your problem to worry about.

 

[mrluke]

Just to note , Im not leaving the battery sitting @ 100%

Im driving the car every day, so its decreasing on average around 20-25% per day when being used.

Thanks everyone for the information though . I actually run TeslaMate from home and it states on my last charge

47% to 100% / Efficiency was 95% @ 5.0c ( 34.24kWh used and 32.59kWh added ) ( 4.7 hours duration )

 

[WannabeOwner]

> Whats the best way for setting a charge schedule ?, Via the Tesla or via the Gen3 Tesla charger.

I just use the car's schedule. Thus my Charger is always powered - so if I come home daytime and need to charge immediately I can just start it from the car.

Also, the car schedule will always start at Off Peak - there isn't any internet or anything else that needs to be "up" to make that happen. It will also start charging if I come home late (several hours after Start time).

But its probably splitting hairs vs controlling from Charger end and using the Charger APP to override if needing a day-time charge etc.

What about pre conditioning before departure? Would a charger-schedule be off at that time? That might be a reason to schedule from car - then you can just use APP 5 - 10 minus before departure to turn Climate on.

The only negative with this is that Car Schedule will NOT stop at the end of off peak - so if you come home "empty", and want to replenish to "full" over two nights, you'll have to intervene - e.g. set LIMIT to 30% more than SOC on day one, and increase by another 30% on day two (adjust that 30% to whatever your car can add during the duration of your off peak tariff)

> Is only running my batterys down to 50% most of the time bad ? should i be going lower to like 30/20% ?

My view is that I might need to go somewhere unexpectedly so I plug in whenever I come home and tomorrow morning I will have a full tank - on the off chance that I might need it.

Pick what percentage you feel comfortable with for "full tank" - 80% / 90% etc.

And then one-a-week / similar set the LIMIT to 100% for LFP recalibration benefit.

 

[Astrape]

It’s a good question so I decided to dig a little deeper.
This chart says that for LFP sitting at any charge >70% may increase the rate of calendar aging, ie salt formation on the anode which reduces the battery capacity by a few percent.
Calendar aging tails off rapidly after the first year, on LFP it causes capacity loss typically 2.5-4% in year 1, then tailing off with similar additional loss over the battery lifetime.
Whether accelerating the rate of aging at the start by high state of charge increases the overall loss is not clear from anything I read. My verdict is if its not clear its not worth worrying in the context of the high life and stability of LFP

Figure 5 from Calendar Aging of Lithium-Ion Batteries I. Impact of the Graphite Anode on Capacity Fade | Semantic Scholar

Figure 5. (a-c) Anode potential over SoC from half-cell measurements; (d-f) capacity fade over storage SoC for different storage periods. The location of the central graphite peak in the new condition is highlighted by a dotted vertical line. - "Calendar Aging of Lithium-Ion Batteries I. Impact...

www.semanticscholar.org

 

[Astrape]

In this chart (topone) from the Preger paper, we can see that it makes little difference to the cycling degradation when the discharge is 0-100%. To 80% capacity remaining (20% degradation) the number of cycles with 40-60% cycling is about 7800 and for 0-100% is 6500. The contrast with the NCA battery is noteworthy. So again the implication is that it doesnt make a lot of difference whether you use the full battery depth of discharge.

6500 cycles is over a million miles. At an average 12000 miles a year for 20 years, 1200 cycles are needed. So for normal users LFP batteries on paper have more than enough life. What we need to confirm these bench tests is more years of experience of Tesla LFP. But nothing I have seen reported in the fleet data so far warns us that keeping high state of charge or high discharge depth is causing unexpected loss of capacity.

Preger et al battery degradation vs cycling depth, temperature, discharge rate

 

[Ashdeman]

> They say charging LFP batterys to 100% each time is the way to go, does it use a lot more electricty getting from say 90% to 100% ? More cost effective to only charge to say 90% or 80%.

> Is only running my batterys down to 50% most of the time bad ? should i be going lower to like 30/20% ?

> Whats the best way for setting a charge schedule ?, Via the Tesla or via the Gen3 Tesla charger.

According to TeslaFi my Model 3 RWD charged at 95% efficiency last night when going from 25% to 72%, ill let you know what it says when I top up to 100% tonight/tomorrow night.

I tend to let mine go down to 20-30% and then charge it back up to 100% over the next 2 or 3 nights (only get 4 hours on cheap rate leccy), I don't think it matters though wether you recharge at 50% or 30%. If I needed range the next day for a trip then I'd happily charge it from any state of charge.

For me I've just set my Hypervolt charger to only charge between 0:30-04:30, leave the cars charge limit @ 100% and just plug it in - its worked flawlessly everytime. I heard that it can be a bit off a faff getting the cars schedule to charge only during off peak hours, you can set a start time or an end time but not both I think, so you end having to mess with the charge limit slider to ensure it will end before the off peak rate ends.

 

[WannabeOwner]

I heard that it can be a bit off a faff getting the cars schedule to charge only during off peak hours

Yes ...

so you end having to mess with the charge limit slider to ensure it will end before the off peak rate ends

Given you've got TeslaFi you could put a schedule to STOP charging at end of Off Peak

You could also schedule to set LIMIT to 100% just before off peak, once a week, or something like that. And then to turn it down (e.g. to 80% / 90%) after Off Peak finishes, on that day)

And an ALERT if you forget to plug in and, say, the SoC is below 50% ...

And to set the AMPS to 32 just before Off Peak ... in case you've manually turned them down for any reason ...

... yup, all of those have caught me out at some point in the past!

I don't think it matters though wether you recharge at 50% or 30%. If I needed range the next day for a trip then I'd happily charge it from any state of charge

Maybe you wouldn't forget! I would, at least once-in-a-while, so I prefer to charge the car up to a set limit (e.g. 80% / 90%) so that I am sure to have charge if I need it "tomorrow" - potentially "unexpectedly"

 

[Ashdeman]

TeslaFi still reported 95% efficiency when charging from 53%-100% last night

 

[Unknowuser2022]

This is supposedly not the case for LFP, as the cell voltage is a little lower than NCA.

Charging to 100% means you're not going to get regen for a portion of the next journey. I'd suggest you charge to 80% most of the week, then one night a week charge to 100%

I have an LFP model Y. I charge to 100% every day. I can absolutely confirm, that regen from 100% is perfectly acceptable, if anything the overall regen is better. I can’t even tell if there is a difference in regen between 80% and 100%. They’re never a need to use the foot brake for normal driving. (I had a M3 previously and that has 0 regen from 100%). Based on degradation performance, I don’t want anything other than an LFP Battery car in the future.

 

[Unknowuser2022]

This is supposedly not the case for LFP, as the cell voltage is a little lower than NCA.

Charging to 100% means you're not going to get regen for a portion of the next journey. I'd suggest you charge to 80% most of the week, then one night a week charge to 100%

I have an LFP model Y. I charge to 100% every day. I can absolutely confirm, that regen from 100% is perfectly acceptable, if anything the overall regen is better. I can’t even tell if there is a difference in regen between 80% and 100%. Theres never a need to use the foot brake for normal driving. (I can say this as I had a M3 previously and that has 0 regen at 100%). Based on degradation performance, I don’t want anything other than an LFP Battery car in the future.

 

[LEE3]

Byorn Nyland conducted a test on an early RWD LFP M3 where he ran the car down to it completely shutting down and managed to drive an extra 40 or 50 kilometres once the % hit zero. This suggests there’s a significantly larger capacity with these batteries which Tesla hides so any battery degradation, particularly in the first year of use will most probably be absorbed with this hidden portion of capacity that Tesla hide from us.

 

[WannabeOwner]

regen from 100% is perfectly acceptable,

Do you have the "blended brakes" in Aust? (Which AFAIK we don't in UK ... I thought it was only USA). If that's the case would you know if it was regen or brakes at 100%? (I don't know the answer as not had the opportunity to try it )

 

[Adopado]

I have an LFP model Y. I charge to 100% every day. I can absolutely confirm, that regen from 100% is perfectly acceptable, if anything the overall regen is better. I can’t even tell if there is a difference in regen between 80% and 100%. Theres never a need to use the foot brake for normal driving. (I can say this as I had a M3 previously and that has 0 regen at 100%). Based on degradation performance, I don’t want anything other than an LFP Battery car in the future.

Is Aust Australia or Austria? If Australia I doubt that the battery is being challenged by low temperatures at present. I'm guessing that regen at 100% may be different after a properly cold night.

 

[qwickshot]

Speed is really relevant when considering regen. Max regen is a fixed power amount at a given SOC and battery temperature but the faster you go, the more power you need to slow down.

Regen at 100% is fine when you are going <30mph, it’s pretty normal.

However, if you are going 70 mph, you get about the same amount of regen power as when slowing down from 30 mph but as there is so much more energy and inertia, you really don’t slow down at all for a really long time. If you charge to 100% and then go down a hill, it will stop regenerating pretty quickly as it can’t take any more.

 

[Jason71]

Speed is really relevant when considering regen. Max regen is a fixed power amount at a given SOC and battery temperature but the faster you go, the more power you need to slow down.

The key point being that it is a squared relationship so the kinetic energy the car is carrying at 60mph is 4 times what it is at 30mph rather than double while the energy consumption of the regen is fixed so the rate of regen deceleration at 60mph would be half what it is at 30mph.

Overall deceleration would not be half since air resistance would be greater ( also a squared relationship) which would mask this to some degree but not sure how much. We always ignored that in the GCSE maths I am using here