Sudden range loss and battery popping at SC

[Judders]

So my model 3 has been pretty much always been charged between 90% and 50% while driving and charged to 90% and always plugged in when not in use as recommended in the manual. My range at 90% has been 279/278 pretty much all of the 9500 miles we have had the car until about a month ago.

About a month ago and shortly after the 2020.4 update it randomly dropped to 270@90 and as low as 262@90. Currently it is at 300 at 100%. I always got 310@100 the few times I have taken it there before a trip

I actually saw an increase to 281/282@90% about a week to two before this drop, never went to 100 to see if it was more then 310 but showed 312 on the app if I were to select it.

So after the drops I switched into percentage mode and at one point I only had a max capable of 98%@100 and 49%@50. Talking to the Tesla service center they said that even with degradation that should still always show 100% (seems to be mixed information on this available) and that they expect up to 10% loss the first year on most model 3s, glad I got the longer range. Anyhow I certainly hope that there isn’t this much degradation after such few cycles. I have also had the popping of the battery almost anytime I use a supercharger and that includes preconditioning the battery. Bug reports of course when it happened so it’s documented. It usually would do that once or twice while there, I’ve been told that’s just a pressure valve and not to worry but being they have replaced that on other vehicles and it was fixed to my understanding before I purchased mine I’m slightly worried.

So it will finally get looked at by the service center wednesday this week for that and few other items(hood needs adjustment, broken weather strip connector under the hood, and some paint peeling on the front fender, a lot of exposed primer under the hood).

For a 50k vehicle I of course still love it despite the issues but I really wish Tesla would just make the mileage reflect the epa rating for 310 like they do with the percentages, so it’s not in mine or anyone’s minds. Furthermore with the 325 mile range update and now claimed 350 reached for the same awd dual motors I really hope Tesla would give that to their customers since they claim it’s just software changes.

Will be doing the full charge down to 10% or so and see how many kws total are used down to see if it’s truly just an off calculation and will update that here.

Any thoughts or ideas would be great and if your battery is popping when supercharging please share as well.

 

[DirtyT3sla]

Battery still makes the noise while supercharging, even the updated valves. It's completely normal, especially when it's cold out. As for the 350 mile range, that wasn't Tesla, that was CR doing some random test.

 

[G26okie]

Hah man they better not expect 10% the first year, I expected 10% by like 100k-150k miles

 

[Judders]

Battery still makes the noise while supercharging, even the updated valves. It's completely normal, especially when it's cold out. As for the 350 mile range, that wasn't Tesla, that was CR doing some random test.

Thanks was just watching a few of your guys videos

 

[Judders]

Hah man they better not expect 10% the first year, I expected 10% by like 100k-150k miles

What they told me on the phone for most model 3s. Then drastically slower after. I agree and certainly hope it’s not true.

 

[DaveRZ]

I've seen the percentage being off by a bit on the app quite frequently on mine. It seems the app's percentage doesn't always line up correctly with the car's percentage. Mine was showing 48% the other day at the "50%" mark. Further, if I set my charge to 80% then checked in the car, it was actually closer to 78% (charge hadn't actually happened yet, just comparing where the limit line was placed on the screen).

I don't think there's any real problem here other than the usual rounding errors that present themselves when you try to manage a lithium battery with any accuracy.

 

[AlanSubie4Life]

9500 miles we have had the car until about a month ago.

. Currently it is at 300 at 100%

Sounds like you're doing great. Only 3.3% capacity loss (might actually be a bit more but never mind that, it is still good). The likely reason you didn't see any loss of capacity over the first 9000 miles is that that loss of capacity was hidden from you in the form of more energetic rated miles. (There's no way to tell now, but there is evidence on YouTube that this happens.) That's why I say your actual capacity loss might be larger than 3.3%. (If I had to guess, I would guess you have lost about 7-7.5% from your original kWh capacity (you currently have 73.5kWh including the 4.5% (3.3kWh) buffer below 0%).)

I think 10% loss of capacity over the first one to two years is a nice reasonable and safe expectation (and a good result). Not a big deal and totally expected for any electric vehicle. My Spark EV has lost 20% or so over 3 years and it only started with around 19kWh!

The % thing is just a rounding error issue in the app display; it's not real. Separately, sometimes you'll find that your car stops charging at 98% or so, and you'll have to run it down again in order to be able to retrigger a charge to 100% - totally different issue though.

Will be doing the full charge down to 10% or so and see how many kws total are used down to see if it’s truly just an off calculation and will update that here.

Remember you have to do one continuous drive without stopping at all to measure these kWh. You can't stop, and you can't spend any time in Park. Also it has to be a nice warm day in Temecula. No starting out at 40 degrees!

I would expect if you go from 300 miles down to 0 miles that you'll see:

(73.5kWh-3.3kWh)*0.98 = 68.8kWh on the trip meter.

The 0.98 is the trip meter correction factor (approximate).

It may be easier and no less accurate to log your charging voltage, current, and charging time from near 0 miles, to the nearest minute, to 100%, and multiply by your charging efficiency (about 0.885 (to 100%) - 0.89 (to 90%) for 32A charging). That will give you your kWh available at 100%, all the way down to 0% (not including the buffer). You do need to correct the efficiency for your charge rate. And it can't be cold of course (no energy can be spent warming the battery otherwise the calculation will be wrong).

 

[Judders]

Sounds like you're doing great. Only 3.3% capacity loss (might actually be a bit more but never mind that, it is still good). The likely reason you didn't see any loss of capacity over the first 9000 miles is that that loss of capacity was hidden from you in the form of more energetic rated miles. (There's no way to tell now, but there is evidence on YouTube that this happens.) That's why I say your actual capacity loss might be larger than 3.3%. (If I had to guess, I would guess you have lost about 7-7.5% from your original kWh capacity (you currently have 73.5kWh including the 4.5% (3.3kWh) buffer below 0%).)

I think 10% loss of capacity over the first one to two years is a nice reasonable and safe expectation (and a good result). Not a big deal and totally expected for any electric vehicle. My Spark EV has lost 20% or so over 3 years and it only started with around 19kWh!

The % thing is just a rounding error issue in the app display; it's not real. Separately, sometimes you'll find that your car stops charging at 98% or so, and you'll have to run it down again in order to be able to retrigger a charge to 100% - totally different issue though.



Remember you have to do one continuous drive without stopping at all to measure these kWh. You can't stop, and you can't spend any time in Park. Also it has to be a nice warm day in Temecula. No starting out at 40 degrees!

I would expect if you go from 300 miles down to 0 miles that you'll see:

(73.5kWh-3.3kWh)*0.98 = 68.8kWh on the trip meter.

The 0.98 is the trip meter correction factor (approximate).

It may be easier and no less accurate to log your charging voltage, current, and charging time from near 0 miles, to the nearest minute, to 100%, and multiply by your charging efficiency (about 0.885 (to 100%) - 0.89 (to 90%) for 32A charging). That will give you your kWh available at 100%, all the way down to 0% (not including the buffer). You do need to correct the efficiency for your charge rate. And it can't be cold of course (no energy can be spent warming the battery otherwise the calculation will be wrong).

Thanks that was super informative! At the service center now and their replacing the front bumper because of paint issue, adjusting the hood, replacing the broken weather strip connector and had already ran diagnostics on the battery before I was here. Will share the report once I get it but they said it appears all normal and the recommend running the battery down to 20% more often to help with the BMS calculation. I supercharge rough 20% of the time by their report. Granted I only do it at all because I got 2 years free when I got the car. Have needed to maybe once or twice otherwise.

 

[Judders]

So here’s a picture of their recommendations for the battery range, no mention of degradation.

<10% to 100% once a month
Down to Around 20% and charge to 90% once weekly
And vary the store capacities so say 80 one charge 90 next 75 another time etc.

 

[DaveRZ]

Thanks for sharing that!

I'm fully in agreement with occasionally going low and high on the charge levels in order to keep the computer calibrated to the voltage of the pack. High charge equalizes the modules, and low and high voltages calibrate the computer. Laptop and cell phone manufacturers have been suggesting this for years.

I'm skeptical about the whole "don't charge" some nights and leave it at varying levels as much as you can idea. This seems to fly in the face of what we've been told by Tesla, and what my general understanding of how battery management computers work. I see no logical benefit that "sitting" at 40% overnight would do (for battery estimates) since there's no equalization, and its not like the computer will be about to somehow get a more precise reading by sitting overnight. But hey, I'm not a battery engineer.

I had a service writer at a Chevy dealership once try to convince me that Chevy truck parts were slightly better than GMC truck parts (the "good stuff" goes to the chevy trucks first, then the rest goes to the GMCs). He really wasn't kidding, was totally serious, and had been working there for quite some time. Oh, and the same company owned the GMC dealership next door, so its not like he was just trying to drum up business.

What I do take away from this is a reinforcement of my belief that all information you are told must be taken with a healthy dose of skepticism. People add their own spin to information they hear, intentionally or not. Even official information from Tesla on battery care that came from their engineering department still had to go through marketing, legal, pubic affairs, etc... before being sent out. Its a guarantee you're never getting the whole story.

 

[Wennfred]

My battery took a dump after 2020.12.1