Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health

[Jeremy3292]

Why wouldn't it see the bottom 50%? Just skip a day of charging, and boom, bottom 50%! You are welcome!

and you are overthinking this, and there are WAY too many variables.

As a datapoint, I had a 70 mile roundtrip commute for the first 20 months of 3 ownership. I'd charge every few days at work, sometimes one, sometimes two, occasionally three, depending on how busy the free chargers were. Pretty much always charged to 90%. I had an HPWC at home and almost never used it. Still don't, but that's because I haven't commuted to work in person since Covid. At this point, I charge once or maybe twice per week. I try to let it get down to 10-20% every now and again, but its pretty hard. Stacy's Mom is sitting out in the garage right now with 127 miles(44%) remaining(aka 289 miles at 100%), not plugged in.

Look at this thread for some more information... How I Recovered Half of my Battery's Lost Capacity

Yes, I have seen that thread many times. It is quite long winded.

My point was Tesla recommends plugging in every single day in the owners manual and based on my routine driving schedule I would never hit below 60% if charging to 90% every day.

So my plan was to vary my charging to 70% 80% 90% and not plugging in every single day so my battery sees the bottom half SOC.

 

[AlanSubie4Life]

So my plan was to vary my charging to 70% 80% 90% and not plugging in every single day so my battery sees the bottom half SOC.

I would plug in every day if convenient and set the SOC to the minimum that very comfortably gets you through the day.

Batteries do best with lower SOC and minimum cycle depth. But I don’t think these will likely dominate the capacity loss you see.

But there will be no way to do the counter factual, so may as well just do what is supposed to be best.

As a bonus it matches Tesla recommendations!

The only downside of not seeing the lower 50% is that somehow it might screw up the BMS but 1) that is not likely to happen 2) it is easily rectified and 3) you’ll probably use low SOC in the regular co

This is what I would do if I could redo things rather than using 90% SoC a fair amount in the beginning (though I doubt it had much impact).

 

[Jeremy3292]

I would plug in every day if convenient and set the SOC to the minimum that very comfortably gets you through the day.

Batteries do best with lower SOC and minimum cycle depth. But I don’t think these will likely dominate the capacity loss you see.

But there will be no way to do the counter factual, so may as well just do what is supposed to be best.

As a bonus it matches Tesla recommendations!

The only downside of not seeing the lower 50% is that somehow it might screw up the BMS but 1) that is not likely to happen 2) it is easily rectified and 3) you’ll probably use low SOC in the regular co

This is what I would do if I could redo things rather than using 90% SoC a fair amount in the beginning (though I doubt it had much impact).

I’m likely only going to use 30% of the battery daily based on ABRP. I want to make sure that BMS calibrates appropriately (even though that’s just a visual thing for the most part) and that I keep the battery in the best health possible.

So I figured if I vary my top SOC between 70% 80% and 90% then my battery will also see 40% 50% and 60% SOC daily (based on a daily 30% DOD). Or I just skip charging one day and take it down to 20% or 30%.

My understanding is you should keep the SOC between 20% and 90% if possible and vary the SOC levels so you are not stuck in one small SOC range. Is that a correct way of thinking?

Also when you say minimal cycle depth are you referring to per use DOD before the next charge?

 

[AlanSubie4Life]

Also when you say minimal cycle depth are you referring to per use DOD before the next charge

Yes

I want to make sure that BMS calibrates appropriately (even though that’s just a visual thing for the most part)

This is way overblown, unless you absolutely never take longer trips, maybe. And maybe not even then. I’ve never seen any significant miscalibration of my pack capacity. It’s rock solid. It may also be better at estimating that it used to be, so some of the lore may now be false legacy info which no longer applies.

It happens of course. Depends on the pack. But does not seem to happen to everyone.

Simplest to keep it simple and change it if it is problematic.

 

[AlanSubie4Life]

I charge the M3 to 317 miles (about 91%) -

This means you have some capacity loss or a car with a BMS that has not figured things out yet. It thinks you are at 76.8kWh.

Interesting with a new 2021 which should be at 79kWh plus and should not show any loss for a while. That is why I think it has just maybe not figured it out yet. Happens occasionally though rare.

I notice the battery indicating estimate miles showing around 300 mils...

This large jump is weird but it does happen. What does the trip meter say?

91% charged (317 Miles) - when I come home dropping them off, the battery shows 285 miles; basically, the battery used 23%, for a 16miles trip (roundtrip) - which is high for EV for that short trip.

This is 9%. This could definitely happen. Would take about 400Wh/mi though; high for this time of year. Remember energy used while parked is not counted on the trip meter. What did it say?

 

[Jeremy3292]

Yes

This is way overblown, unless you absolutely never take longer trips, maybe. And maybe not even then. I’ve never seen any significant miscalibration of my pack capacity. It’s rock solid. It may also be better at estimating that it used to be, so some of the lore may now be false legacy info which no longer applies.

It happens of course. Depends on the pack. But does not seem to happen to everyone.

Simplest to keep it simple and change it if it is problematic.

Thanks. So based on what you said previously the routine I should likely follow is to charge to 80%, my daily DoD will generally be 30% leaving me at 50% SoC every evening, and then charge to 80% and do it all over again to keep the daily DoD low. And yes of course I'll run errands and take road trips so it's not a hard and fast rule just a general practice.

"I would plug in every day if convenient and set the SOC to the minimum that very comfortably gets you through the day.

Batteries do best with lower SOC and minimum cycle depth."

 

[AlanSubie4Life]

So based on what you said previously the routine I should likely follow is to charge to 80%, my daily DoD will generally be 30% leaving me at 50% SoC every evening, and then charge to 80% and do it all over again to keep the daily DoD low

Or you could do 60% or 70%. It depends how often you expect to end up in a situation where you will use a lot more than 30% and what you are comfortable running down to. 70% is better than 80% as it will give better regen when it is cold.

You know you are setting too low when you have to worry about your SOC during the day, or you park below 20% and cannot use features.

 

[Jeremy3292]

Or you could do 60% or 70%. It depends how often you expect to end up in a situation where you will use a lot more than 30% and what you are comfortable running down to. 70% is better than 80% as it will give better regen when it is cold.

So I could also vary top SoC at 60% 70% and 80%, correct?

 

[AlanSubie4Life]

So I could also vary top SoC at 60% 70% and 80%, correct?

Of course, it just depends on how much you want to fiddle around. It is supposed to be easy. Changing the set point all the time, assuming you charge every night, doesn’t really change the effective depth of discharge very much (average swing ends up the same, all else being equal, I think). Plugging in every night is what minimizes that. (Not talking about the minimum - talking about the swing.)

As I said, these factors are unlikely to matter much in any case. They might, though! Just not a lot of evidence suggesting that they matter much for the Tesla batteries to date.

 

[Candleflame]

Yes

This is way overblown, unless you absolutely never take longer trips, maybe. And maybe not even then. I’ve never seen any significant miscalibration of my pack capacity. It’s rock solid. It may also be better at estimating that it used to be, so some of the lore may now be false legacy info which no longer applies.

It happens of course. Depends on the pack. But does not seem to happen to everyone.

Simplest to keep it simple and change it if it is problematic.

It used to be an issue on old 2018 cars when tesla had a different bms algorithm where cars would experience a memorylike effect if theyd spend a lot of time sitting between 40 and 70%. But has since then been patched. Presumably this is where the notion comes from. The temporary soc miscalibration still happens, ie my car spent the last 8 weeks at 50 to 60%. Few days ago i charged the car to 70%. When it woke up from sleep it was at 74%. It does not seem to affect rated range anymore though its almost like model 3 ignores 50% soc voltage readings now. The downside could possibly be that if i would have charged to 98% the car may have overshot slightly to i. E. 101%. But id hope even hot voltage readings become a lot more accurate at high soc.......

 

[Scottish mod3]

What can 6,000 electric vehicles tell us about EV battery health? | Geotab

Found this interesting insights factors that correlate to EV battery degradation based on real world data. Was researching on best charging practicer or what not to do... As planning to keep my M3 for long time... Although, not sure how relevant it is on the new MIC LFP batteries which has a diff chemistry than typical NCA/NCM. Interesting read anyway..

 

[mdanieltech]

So I've had my M3 LR for 2 months and I've watched the range percentage when I do my normal weekly driving to work.

Round trip it takes roughly 20% (Not including after work driving)

I've read around that you shouldn't charge to 100% or drop below 20% unless your going on a trip

My question is this

Wise to charge to 100% for the week wear it down to almost 0% by Friday?

or

(What I'm doing right now)
Charge to 80% and not letting it dip below 30% normally charging every other day/every 2 days

Just trying to get the best life out of my battery

Thank you

 

[ro_explorer]

Wise to charge to 100% for the week wear it down to almost 0% by Friday?

No, not wise at all. You will stress the hell out of the battery. Keep it 80-20 as much as comfortably possible.
You say it is taking 20% round trip ... then keep it 60-80, or better yet, 40-60 daily. This applies, of course, to the scenario in which you have a charger at home and can comfortably plug in every day. Keeping the battery swing low will lower the chemical stress, therefore, slower aging.

I kind-of abused my M3LR in the first 2 months of ownership and I lost 5kWh battery already. I only have 10K Km and almost 3 months since I got it brand new and the Max nominal capacity is 76kWh (down from 82 theoretical max as new - more like 81 realistically).

 

[Candleflame]

I kind-of abused my M3LR in the first 2 months of ownership and I lost 5kWh battery already. I only have 10K Km and almost 3 months since I got it brand new and the Max nominal capacity is 76kWh (down from 82 theoretical max as new - more like 81 realistically).

this is not related to you charging to 100% or abusing your battery. Your degradation is normal. 5% first year, then quickly moving to 8-10% in the second year. This is average, some cars will be a bit better, some worse.

As for the OT, dont charge to 100% unless you have to (i.e. roadtrip) but its especially important to not keep it there. avoid 90% if its hot (i.e. >25C) and just use 80-85% instead.

 

[ro_explorer]

5% first year

9 weeks is far from "first year" ... is not even first quarter. After 9 weeks was at 76.5 ... now, at 11 weeks old. 76.1 ...
My cell phone has less degradation after a year than my car got after not even 3 months.

 

[Tam]

Wise to charge to 100% for the week wear it down to almost 0% by Friday?

No. Not wise. Your owner's manual says there's no benefit to delay charging.

Both extremes of 100 and 0% are bad.

Driving at lower end is worst. If you have to choose on a road trip then choose the lesser evil of 100%.

Your 12V battery doesn't get recharged from your main battery pack at its lower end. Due to Ohm's law, the motor doesn't spin unless there's enough power.

Power = Voltage x Current

When your Voltage drops, the law would torture your cell by squeeze all the Current it can get in order to yield the same Power to move your car.

or

(What I'm doing right now)
Charge to 80% and not letting it dip below 30% normally charging every other day/every 2 days

Just trying to get the best life out of my battery

Thank you

Charge at 90% as soon as you can. There's no advantage for your battery health to wait.

 

[Candleflame]

9 weeks is far from "first year" ... is not even first quarter. After 9 weeks was at 76.5 ... now, at 11 weeks old. 76.1 ...
My cell phone has less degradation after a year than my car got after not even 3 months.

im not sure what you are obsessing about. How many kms of rated range have you lost?

 

[oreobbq]

So I've had my M3 LR for 2 months and I've watched the range percentage when I do my normal weekly driving to work.

Round trip it takes roughly 20% (Not including after work driving)

I've read around that you shouldn't charge to 100% or drop below 20% unless your going on a trip

My question is this

Wise to charge to 100% for the week wear it down to almost 0% by Friday?

or

(What I'm doing right now)
Charge to 80% and not letting it dip below 30% normally charging every other day/every 2 days

Just trying to get the best life out of my battery

Thank you

So you know what's recommended and you're asking if you should go ahead and do the opposite..

 

[KenC]

...
My question is this
Wise to charge to 100% for the week wear it down to almost 0% by Friday?

or

(What I'm doing right now)
Charge to 80% and not letting it dip below 30% normally charging every other day/every 2 days

Shallow discharges are best for longevity, so the first option is the worst choice. The second option is okay, but Tesla recs keeping it plugged in, so the best option is keeping it topped up. You can run 80-60, daily, just fine. Of course, it's possible that 60-40 is better, but the difference is likely quite minimal. But, between 80-60 or 60-40 is fine. Choose what's convenient. I run 60-50 for my 30 mile commute. Works for me. YMMV.

 

[ro_explorer]

im not sure what you are obsessing about.

Extremely high degradation in just few weeks of use. 3-5% in a year is fine, 6% in little over 2 months is bad.

How many kms of rated range have you lost?

16Km so far, in just 2 months. Brand new was showing 570 at 100% ... now it is showing 554 at 100% and that value is decreasing with 1 Km every few days, after almost every charging session ... even if I charge 20-60%.