290mi at max charge after 6 months

[jpfive]

2021 MYP March build, 82kwh pack. 6,000 miles on odometer. My estimated mileage varies quite a bit, between 280-300mi. Sometimes the 100% SOC estimate will show low 280s, other times it will be in 290s. It’s interesting how mine varies so much with such few miles, but I’m not overly worried about that low number. Daily charge usually set between 60-80% except for trips I charge 100%

I routinely take a 225mi all highway trip door-to-door with this car, and although my number estimate has dropped under 300mi at 100% charge, what is interesting to me is that my SOC on arrival has essentially remained unchanged since it was new on this predictable/repeatable drive. Typically driving 78-80mph on autopilot, using 310-320ish wh/mi, 71-73Kw from trip computer, and have always arrived with a few percent remaining.

This means that my usable range in the car has not actually degraded like the BMS sometimes suggests when displaying lower EPA mileage estimate numbers at me.

Same here (see earlier post). %SOC is a real number. Range is a construct - a living, breathing, animal that varies by constantly changing conditions. We worry too much. Cheers.

 

[AlanSubie4Life]

This means that my usable range in the car has not actually degraded like the BMS sometimes suggests when displaying lower EPA mileage estimate numbers at me.

I doubt your 100% charge has changed that much yet from the 303 miles. It is probably just under 300 miles. What was it exactly on your last 100% charge?

My estimated mileage varies quite a bit, between 280-300mi. Sometimes the 100% SOC estimate will show low 280s, other times it will be in 290s.

This is not the BMS estimate, to be clear.
The picture you provide of the battery gauge with extrapolation showing 283 miles should be ignored. It is just an extrapolation and does not use BMS information (except for the current rated miles remaining).

I recommend mostly ignoring these estimates and quoting them only when you are at over 80-90% SoC, when they will be within a few miles of correct. The actual BMS energy estimate (your rated miles remaining) is actually usually quite accurate (seems typically within a couple % at a high SoC).

The reason you have been able to make that trip with minimal changes to ending SoC is because you have probably not lost more than 1-2kWh of capacity (about 4-8 rated miles) so far.

It’s good that you have such a trip - it is a good benchmark for you - in a year or two you’ll likely need to Supercharge somewhere along the route briefly to make it comfortably (or drive more slowly or draft more consistently). No big deal.

The 72-73kWh is exactly what you’d expect for (say - you said a few % arrival) a 97% discharge:

73kWh/0.99/0.97/0.955 = 79.6kWh

So within about 1-2kWh of your original 80.6kWh degradation threshold.

 

[roblab]

Normally any battery will degrade approximately 5% the first year and then about 1% each year thereafter. It is possible that in some instances degradation will be less.

But if someone buying a new Tesla thinks that they will keep the full rated range over several years, that's just wrong. It doesn't happen. If someone NEEDS to have a large amount of range five years from the purchase date, they need to purchase more range now, ie: buy the bigger battery. If the M3 battery won't give you enough, one might have to move up to a different car. Mine gets over 400 miles on a charge. So far.

With chargers every hundred miles or so in many parts of the country, having bigger batteries are probably not as necessary other than for convenience, but one should never buy the smallest size battery available thinking range will stay the same.

 

[JWAMY]

I doubt your 100% charge has changed that much yet from the 303 miles. It is probably just under 300 miles. What was it exactly on your last 100% charge?


This is not the BMS estimate, to be clear.
The picture you provide of the battery gauge with extrapolation showing 283 miles should be ignored. It is just an extrapolation and does not use BMS information (except for the current rated miles remaining).

I recommend mostly ignoring these estimates and quoting them only when you are at over 80-90% SoC, when they will be within a few miles of correct. The actual BMS energy estimate (your rated miles remaining) is actually usually quite accurate (seems typically within a couple % at a high SoC).

The reason you have been able to make that trip with minimal changes to ending SoC is because you have probably not lost more than 1-2kWh of capacity (about 4-8 rated miles) so far.

It’s good that you have such a trip - it is a good benchmark for you - in a year or two you’ll likely need to Supercharge somewhere along the route briefly to make it comfortably (or drive more slowly or draft more consistently). No big deal.

The 72-73kWh is exactly what you’d expect for (say - you said a few % arrival) a 97% discharge:

73kWh/0.99/0.97/0.955 = 79.6kWh

So within about 1-2kWh of your original 80.6kWh degradation threshold.

Thanks for info. I usually keep display on percent instead of miles so I’ll need to check if it charges higher than 280-290 next time I take this trip and charge it to 100%. Trip is 224mi, usually arrive with 1-3% SOC. Here is last weeks trip at 50% SOC and half through trip.

never checked when it was brand new what mileage it charged up to so I just have what others report for the mileage estimate at 100% SOC

 

[AlanSubie4Life]

usually arrive with 1-3% SOC. Here is last weeks trip at 50% SOC and half through trip.

So assuming you started at 100%:

36.7kWh/0.99/0.955/0.5 = 78kWh

So I guess I’d expect ballpark 78/80.6*303rmi = 293rmi for you at a full charge.

But lots of rounding errors here so could easily be close to 297rmi, or as low as 290rmi.

Easiest to just see what the car says at 100%. Then you know your approximate capacity loss.

 

[frankvb]

This is not the BMS estimate, to be clear.
The picture you provide of the battery gauge with extrapolation showing 283 miles should be ignored. It is just an extrapolation and does not use BMS information (except for the current rated miles remaining).

Actually it does use information from the BMS - it uses what the BMS currently thinks is the remaining capacity, and what it thinks is the 100% capacity to determine the SoC, and then extrapolates that back to 100%. It's probable not very accurate at low SoC. But maybe you meant the same and just expressed it differently.

 

[a2t2]

mine has 10K miles on it (2020 MYP) and shows 261 at max charge. Ive never used superchargers just my garage level 2 30 amp. I had tesla "diagnose the battery pack" over the air and they said it was normal but Im not so sure. I just bought it used so many the dealer was thrashing it. And I do as well on occasion.

 

[AlanSubie4Life]

Actually it does use information from the BMS - it uses what the BMS currently thinks is the remaining capacity, and what it thinks is the 100% capacity to determine the SoC, and then extrapolates that back to 100%. It's probable not very accurate at low SoC. But maybe you meant the same and just expressed it differently.

There is no capacity from the BMS directly used in these calculations. I said they use the current rated miles remaining (they don’t provide the energy to this API so that’s what you get for energy - which is fine since it directly translates to energy in excess of the buffer, with the constant*0.955). As far as I know, the API only directly has access to these current miles and the state of charge (apparently to only the nearest %). The 100% energy value is not known to the API I gather (otherwise there would be no need to extrapolate!). If the API had access to more significant digits for the SOC, the extrapolation would be better, though at very low state of charge, it would be pretty poor still, since you’d lose perhaps even another significant figure from the miles (single digit). And you’d effectively be extrapolating from a single digit value of miles to a three digit value using a percentage with either one or two digits. Not a recipe for accuracy or precision! In any case the value provided to the user with this extrapolation is typically good to only about two significant figures (so 290, 280, 270, etc.) , and sometimes just one (actually the case here I think) (200/300). In this case his 283 value could potentially be translated to one significant digit, since he may have had single digit rated miles, so in that case about 300 miles is about as good a guess as you can make numerically. Cannot be any more precise than that (saying 280 or 290 would be false precision, and certainly 283 provides false precision).

 

[AlanSubie4Life]

mine has 10K miles on it (2020 MYP) and shows 261 at max charge.

For your car starting at 291 miles (not sure if it got any change in constant), 261 miles is just a 10% capacity loss, which is fairly normal for a car that is over a year old. Higher than many, but not abnormal. It’s a lottery. I doubt using it hard makes all that much difference (there’s not a very large evidence base for heavy kW users).

 

[Silicon Desert]

I agree with the advice to change to the % display in the car. I just did a one time calc of what minimum % I was comfortable with (eg, across town and back + 5%). And then never thought about the range projection again. For daily driving, it doesn’t matter (except maybe that minimum) and for road trips, the trip computer (and ABRP) report to you in %s anyway. So once you get used to it, it saves a lot of brain cells.

Your brain works better than mine. I can't think in terms of percent. I tried it for about 2-3 months when I first got the car. I never saw a street sign that read "X percent to San Francisco". It is easier for me to quickly look at the distance I need to go and compare that to the readout. I agree it might not be as accurate as % or whatever, but it is in the same units of measure as the road signs. I'm just old-school, yet understand that some people like % and some like mileage and that's why Tesla provides both.

 

[a2t2]

+1 for that. And if my car keeps loosing 10% every 10k miles i wont be so happy.

 

[spdracer888]

+1 for that. And if my car keeps loosing 10% every 10k miles i wont be so happy.

Mine is less than a year old and mine NEVER got above that since December of last year.

 

[a2t2]

Hoping that it’s just a lot of short cycling fooling the computer. I don’t usually drive far between charges. But the miles are usually F1 driving lol

 

[AZMurph]

Your brain works better than mine. I can't think in terms of percent. I tried it for about 2-3 months when I first got the car. I never saw a street sign that read "X percent to San Francisco". It is easier for me to quickly look at the distance I need to go and compare that to the readout. I agree it might not be as accurate as % or whatever, but it is in the same units of measure as the road signs. I'm just old-school, yet understand that some people like % and some like mileage and that's why Tesla provides both.

I know what you mean, but I use the nav to tell me if I can get there or not on longer trips. The miles projection is based on rated miles and not accurate if you drive faster than the rated wh/mi anyway. It would be great if the car had an option to show you both miles and % at the same time. Then everybody would be happy.

 

[AZMurph]

I know what you mean, but I use the nav to tell me if I can get there or not on longer trips. The miles projection is based on rated miles and not accurate if you drive faster than the rated wh/mi anyway. It would be great if the car had an option to show you both miles and % at the same time. Then everybody would be happy.

Or drive up a hill

 

[Rocky_H]

+1 for that. And if my car keeps losing 10% every 10k miles i wont be so happy.

The good news is: Your car will NEVER lose any %!! It will ALWAYS say 100% when it's holding as much as it can, no matter how little that is! It's just a fullness measurement--not anything about how much energy that is. See how happy you can be with just using % on the display? (sarcasm off)