2021 SR+ LFP Battery - Usable Battery

[Dozz]

Hi all

I have a March 2021 SR+ with the LFP battery and should have a usable battery of 52.5kwh (as per ev-database). 14000km on the clock

I have been keeping an eye on it lately and all my calculations are indicating that I have only 44kwh usable.

I know its mild but hardly cold by any means here in Ireland.

Have only ever used a Supercharger once. 99% of my charging is at home or in work (11kw charger).
Charge to 100% at lease once a week as per recommendations.
I have Sentry mode off and never precondition the car.
AC would normally be on for my short work commute (9km each way)

Can anyone shed some light on this?

Thanks

 

[MrT3]

The 40 kWh total energy figure is only the energy the vehicle has used whilst actually being driven. Any time spend in Park, pre-heating, sentry mode, daily wake up etc. all contribute to energy consumption but isn't included in that figure so you cannot use it to try and calculate your usable battery capacity.

 

[Dozz]

The 40 kWh total energy figure is only the energy the vehicle has used whilst actually being driven. Any time spend in Park, pre-heating, sentry mode, daily wake up etc. all contribute to energy consumption but isn't included in that figure so you cannot use it to try and calculate your usable battery capacity.

Thanks for that.

 

[Lord Farquad]

Try running it down to 5% then charging it up. My ‘21 Q3 SR+ took 51kw last night from that state of charge. Whilst there will be some charging losses etc I’d expect to see 50+ to help reassure you that the battery capacity is correct. NB the battery has a buffer just over 2kw past 0% so you’ll not get a full 55kw unless you run it way past 0% (dangerous games).

 

[avramd]

Dozz,

Where did you see a recommendation to routinely charge to 100%? My car explicitly warns me not to charge above 90% unless necessary, b/c it will reduce overall battery life. It is also advised not to run the car below 10% charge. Both of these are known to reduce the life of lithium batteries.

Anyway, I'm not quite sure I follow how you are assessing capacity. I assess it with the range estimate at the top of the display (the small battery icon). When my car was new, my rated range was 313 rated miles at 100%. Since I only charge to 90%, my baseline is 280 rated mi @ 90%. I'm at 18k miles on the odometer in 14 months now and my 90% rated range estimate is 265 mi, so I've lost 5.5%.

Earlier on, I appeared to be having more significant range losses - my 90% range was down to 252 rated miles, an apparent loss of 9%. I learned a trick from Tesla that fixes this.

Half of that range loss was an illusion. I was typically plugging my car in when my battery was at 50-70% charge state. The trick is to frequently wait until you are below 40% charge state before plugging back in. It was a slow recovery, but I got 12 miles/5% of estimated battery capacity back over the course of 1.5 months, by doing this regularly. Each individual charge only brought back 1-3 miles worth of estimate, but it rose steadily until my 100% range estimate got up to 296 miles. Then it flattened. Now I make sure that about 1 in 4 charges starts at below 40% charge. That seems to be keeping the battery capacity estimate stable.

 

[spdpsba]

Dozz,

Where did you see a recommendation to routinely charge to 100%? My car explicitly warns me not to charge above 90% unless necessary, b/c it will reduce overall battery life. It is also advised not to run the car below 10% charge. Both of these are known to reduce the life of lithium batteries.

Anyway, I'm not quite sure I follow how you are assessing capacity. I assess it with the range estimate at the top of the display (the small battery icon). When my car was new, my rated range was 313 rated miles at 100%. Since I only charge to 90%, my baseline is 280 rated mi @ 90%. I'm at 18k miles on the odometer in 14 months now and my 90% rated range estimate is 265 mi, so I've lost 5.5%.

Earlier on, I appeared to be having more significant range losses - my 90% range was down to 252 rated miles, an apparent loss of 9%. I learned a trick from Tesla that fixes this.

Half of that range loss was an illusion. I was typically plugging my car in when my battery was at 50-70% charge state. The trick is to frequently wait until you are below 40% charge state before plugging back in. It was a slow recovery, but I got 12 miles/5% of estimated battery capacity back over the course of 1.5 months, by doing this regularly. Each individual charge only brought back 1-3 miles worth of estimate, but it rose steadily until my 100% range estimate got up to 296 miles. Then it flattened. Now I make sure that about 1 in 4 charges starts at below 40% charge. That seems to be keeping the battery capacity estimate stable.

I think the thread is about LFP batteries that come with SR and SR+ (2021) that can be routinely charged to 100%.

 

[MrT3]

Where did you see a recommendation to routinely charge to 100%? My car explicitly warns me not to charge above 90% unless necessary, b/c it will reduce overall battery life. It is also advised not to run the car below 10% charge. Both of these are known to reduce the life of lithium batteries.

It's in the owners manual, but only applies if you have an LFP type battery.

Note
If your vehicle is equipped with an LFP Battery, Tesla recommends that you keep your charge limit to 100%, even for daily use, and that you also fully charge your vehicle to 100% at least once per week.

Model 3 Owner's Manual | Tesla

Learn how to charge your vehicle and use scheduled charging features.

www.tesla.com

 

[Adopado]

Where did you see a recommendation to routinely charge to 100%? My car explicitly warns me not to charge above 90% unless necessary, b/c it will reduce overall battery life. It is also advised not to run the car below 10% charge. Both of these are known to reduce the life of lithium batteries.

The recommendation is from Tesla! Your car's battery has a different chemistry so the advice is different. We're talking LFP batteries as per the thread title and the OP.

 

[gergelyricsike]

Hello guys i have the same MIC 55kw LFP M3. I only able to get 49.3-49.5 kwh. Is it possible that my car does not have the reduced top buffer? I am on latest software, 18.000km on odometer, mainly 75% home charging on 10amps.

 

[kelvin 660]

Only way to tell is with scan my tesla.
I assume you are calculating battery capacity using this method?
Calculating Your Battery's Estimated Capacity Using the Car's Energy Screen
Mine is running at 53 kWh and same mileage as yours. Sep-21 car

 

[GeorgeSymonds]

The guides to calculate capacity only really work if the BMS is calibrated and the cells balanced.

There’s plenty of guides out there on what to do, but you need to 100% charge occasionally plus leave it over night at a low is state of charge if you can. Repeat a few times over a week or two and most see lost range/capacity come back.

 

[gergelyricsike]

Only way to tell is with scan my tesla.
I assume you are calculating battery capacity using this method?
Calculating Your Battery's Estimated Capacity Using the Car's Energy Screen
Mine is running at 53 kWh and same mileage as yours. Sep-21 car

Yes i did it this way.

 

[gergelyricsike]

The guides to calculate capacity only really work if the BMS is calibrated and the cells balanced.

There’s plenty of guides out there on what to do, but you need to 100% charge occasionally plus leave it over night at a low is state of charge if you can. Repeat a few times over a week or two and most see lost range/capacity come back.

I did that also and that way i lost like 4-5km of range.

 

[init6]

Hello guys i have the same MIC 55kw LFP M3. I only able to get 49.3-49.5 kwh. Is it possible that my car does not have the reduced top buffer? I am on latest software, 18.000km on odometer, mainly 75% home charging on 10amps.

Tesla's manual states that you should charge at least once a week at 100% for LFP batteries. This is required to calibrate the BMS. If you've been charging mainly at 75% for 18,000 km, it sounds like you haven't been following the manufacturers guidance and therefore may not have an accurate calibration.
How many times have you charged at 100% and over what period?

 

[HenryT]

Tesla's manual states that you should charge at least once a week at 100% for LFP batteries. This is required to calibrate the BMS. If you've been charging mainly at 75% for 18,000 km, it sounds like you haven't been following the manufacturers guidance and therefore may not have an accurate calibration.
How many times have you charged at 100% and over what period?

See original post:

Charge to 100% at lease once a week as per recommendations.

 

[gergelyricsike]

Tesla's manual states that you should charge at least once a week at 100% for LFP batteries. This is required to calibrate the BMS. If you've been charging mainly at 75% for 18,000 km, it sounds like you haven't been following the manufacturers guidance and therefore may not have an accurate calibration.
How many times have you charged at 100% and over what period?

I was charging to 100% 1-2times per week 75% is my home ac charging rate compared to supercharger usage.

 

[kelvin 660]

I charge (on average) once every 3 days, from ~55% to 100% and keep a record using that method;

Date	Range (miles)	Watt/Mi	SoC	Battery Kw/hr	Range @100%	Degradation
07-Oct-21	223​	242​	100%​	54.0​	215.9​	0.00%​
17-Oct-21	235​	229​	100%​	53.8​	215.3​	0.28%​
13-Nov-21	243​	222​	100%​	53.9​	215.8​	0.04%​
06-Dec-21	212​	252​	100%​	53.4​	213.7​	1.00%​
18-Feb-22	222​	236​	98%​	53.5​	213.8​	0.94%​
23-Mar-22	242​	220​	99%​	53.8​	215.1​	0.35%​
03-May-22	265​	200​	100%​	53.0​	212.0​	1.79%​
08-Jun-22	244​	211​	97%​	53.1​	212.3​	1.65%​

The Range @100% range is calculated using Battery Kw/hr / 250 w/mile (my all time efficiency since I had the car) and Degradation calculated from loss of range.

The degradation of 1.65% is also similar to what I've seen in SmT and also the TeslaFi battery report.

 

[init6]

I was charging to 100% 1-2times per week 75% is my home ac charging rate compared to supercharger usage.

Was or are charging to 100% every week? I suspect you have to keep doing it hence the comment in the manual.

 

[init6]

See original post:

I was responding to the latest query appended to this thread - not the original poster.