Battery estimate high fluctuation

[Alexgd]

We charged up to 90% when we left st Mary mt for Bozeman. In car navigation showed we should arrive at Helena supercharger with over 30% remaining. We drove at 55 mph on a 70 mph highway. Temps were mid 40s and it was raining but not a monsoon.

Over the first hour we watched in increasing consternation as the charge remaining indicator for Helena moved down in fits and starts to 4% before we decided to divert to great falls supercharger, adding an hour to our travel time.

Over three years of Tesla driving I have never seen the remaining charge estimate be so unreliable. Could something be wrong with the car (MYLR)? If the car knows distances, speeds, and elevations for major roads, how could it get the charge estimate so wrong? Any advice?

 

[RTPEV]

I've found the in-car nav to be pessimistic if anything, but usually pretty accurate. That said, I'm not a speed freak, and I'm not usually driving through very mountainous terrain.

That said, I just did an ABRP run with my own (calibrated) car (M3LR, but 2018 model) an starting with 100% at St. Mary, it had me arriving at Helena with 26%. I switched over to a 2022 MYLR starting with 90% SOC and it recommended charging at Great Falls. Setting Great Falls to "AVOID", it had the arrival SOC at Helena at -2%. I added in rain at 40F temp, and it dropped to -10%. Even my own car with those road conditions and 90% start SOC arrived at Helena with 6%. I would not have attempted that trip...ABRP was trying really hard to reroute me to Great Falls or Missoula.

So I would say there is probably nothing wrong with your car's drivetrain/battery--it seemed like it was probably performing adequately.

But your in-car nav telling you you had 30% arrival SOC was clearly an error! That is the mystery. There is no way that was accurate. I hate to sound like I'm asking stupid questions, but are you sure it was the Helena supercharger you were routing to and not one of the alternates?

I guess the lesson is to not put all that trust in the in-car nav (which is surprising because it is usually pretty rock solid). I normally pop up ABRP anyway, but yeah, I would keep an eye on it, and at least for the time being, double check with a second route planner app.

 

[Bouba]

The 2022.16.1.1 update was supposed to add factors like the weather and gradients...so first, do you have 2022.16.1? And if you do, is it possible that Tesla calculated the original estimation before it got any information about conditions and then readjusted...in fact, could the forecast have been much worse than the reality ?

 

[RTPEV]

The 2022.16.1.1 update was supposed to add factors like the weather and gradients...so first, do you have 2022.16.1? And if you do, is it possible that Tesla calculated the original estimation before it got any information about conditions and then readjusted...in fact, could the forecast have been much worse than the reality ?

Good call...except it's still extremely generous for it to suggest 30% arrival SOC, even in perfect weather.

Also wondering if there was some strange driving behavior prior to departure, such as an extended drive at 10mph downhill or something like that? (half serious)

 

[Alexgd]

Thanks for your replies. Since superchargers are few and far between in MT yes it was Bozeman we had plugged into the navigator and it calculated Helena supercharger as an intermediate stop. I could have charged longer to 100% in St Mary but since the car forecast arrival in Helena with 30%+ I felt there was no need since the car nav had always been fairly accurate, much more so than ABRP.

We just got the 2022.16.1 update today so it did not factor into the Montana adventure.

 

[Bouba]

Thanks for your replies. Since superchargers are few and far between in MT yes it was Bozeman we had plugged into the navigator and it calculated Helena supercharger as an intermediate stop. I could have charged longer to 100% in St Mary but since the car forecast arrival in Helena with 30%+ I felt there was no need since the car nav had always been fairly accurate, much more so than ABRP.

We just got the 2022.16.1 update today so it did not factor into the Montana adventure.

Hopefully from now on the estimations will be more accurate

 

[father_of_6]

Just yesterday I took my 5th long road trip in the M3 in 1.5 years of ownership and for the first time, the range estimate was wildly inaccurate. I'm on 2022.16.2.

It first gave a low estimate while Supercharging, causing me to charge an extra 20% above what I actually needed to get home. Once I started driving again, the estimate jumped up significantly. Then while driving, it continued to creep up one percent at a time almost another 8% over the course of 2 hours. Finally arrived home with 5% less than the highest estimate.

For the first time in a year and a half, I no longer trust the guessometer. Sadly, just like almost all other software updates during my ownership, they've once again pushed a regression. I don't think I'd ever buy another Tesla... very disappointing, because it's *so* fun to drive. They just keep making it worse with every software release.

 

[The Lorax]

Similar story here. On a recent road trip, I watched as the estimated battery percentage at destination dropped by nearly 10% shortly after leaving a supercharger, causing us to divert and charge again earlier than anticipated. Yesterday, I watched as the estimated % actually jumped up by nearly 10% part way through the trip, only to see it gradually drop back down to it's original estimate by the time we reached our destination. Is this an issue with the new variables they've introduced into the range calculations? I wonder if battery temp due to supercharging is juicing the estimate at time of charging and then falling out of the calc as the trip progresses and the battery cools?

 

[Bouba]

Similar story here. On a recent road trip, I watched as the estimated battery percentage at destination dropped by nearly 10% shortly after leaving a supercharger, causing us to divert and charge again earlier than anticipated. Yesterday, I watched as the estimated % actually jumped up by nearly 10% part way through the trip, only to see it gradually drop back down to it's original estimate by the time we reached our destination. Is this an issue with the new variables they've introduced into the range calculations? I wonder if battery temp due to supercharging is juicing the estimate at time of charging and then falling out of the calc as the trip progresses and the battery cools?

Is it possible, for example, that a road was blocked...and then cleared...while you were driving ?

 

[avs007]

Without having known other details, it is possible that it added a charging stop and you just didn't realize it. On my last trip a few weeks ago, I was charging at a SC looking at the energy graph, and it said I would arrive at my destination with 20%. I looked at my current SoC and thought that was wierd as I made this trip before. I looked closer at the nav, and saw it was trying to have me make a charging stop somewhere for a few minutes, showing my arrival % at my intended SC as 20%. I had forgotten to tap the remove all charging stops, then the energy graph showed my arrival % as 5% or something like that.

Also, rain makes a huuuuuge difference. On one leg of a different trip, my arrival percentage was shown as 18% but it had started raining quite heavily part way. I ended up arriving with 7%. This is why I always plan for a 20% buffer cus rain and wind can easily sap 10% or more.

 

[The Lorax]

Is it possible, for example, that a road was blocked...and then cleared...while you were driving ?

Good point but because this had happened before, I was watching for route changes etc to try to explain it. I would understand a percentage point here and there but not a sudden jump by +10%. It's almost as if the algorithm was looking back at the last section of driving to predict the rest of the trip. When it dropped the pre-supercharging (cold battery, higher consumption) portion, the estimate jumped up and then slowly decreased for the remainder of the trip as the battery cooled back to normal temps as the temperature effect of supercharging wore off.

 

[shephard357]

Soooo…fast forward to Jan 2024…had the same issue! I added my destination to the nav in the car and it planned 2 stops. Fortunately, I was eating so I let it continue to charge after it said the car said I was good to continue at the first charge stop. When I left the charger, it estimated 29% at the next stop. For the first 20 minutes or so after I departed, the remaining fluctuated +/- 3%…then all of a sudden, it drops to 15%. From there, it slowly drops (over the next 45 minutes to hour) to estimate 9% at next charge stop. I took over and manually added a closer stop.

The stop I added was about 30 miles closer than the original stop…I arrived at the new stop with around 16%!!!. I’d have been on fumes if I’d continued! NOT COOL!

I would absolutely love to know WTH happened and how to predict and avoid in the future. Fortunately, I was in a region and area where I had an intermediate stop…had I not, it would have been far more interesting, and not the good kind. FWIW, on the final leg from the final charge to destination, I arrived with slightly more charge than estimated when leaving the charger…

Anyone have any feedback?!?

 

[Bouba]

I have had two incidents where my energy consumption suddenly tripled without any reason....and that was for my regular commute on the flat ....so, have you checked your energy consumption chart for the trip to find where you were losing energy ? I have found that no matter how much energy I use going uphill, the regen is incredibly efficient and I get a lot back going down. Is it possible that there was a physical problem, brakes binding or something. Whenever you have an anomaly you should photograph all your energy consumption pages before you supercharge and they are wiped out...so it can be analyzed at a later time

 

[Supcom]

I have had two incidents where my energy consumption suddenly tripled without any reason....and that was for my regular commute on the flat ....so, have you checked your energy consumption chart for the trip to find where you were losing energy ? I have found that no matter how much energy I use going uphill, the regen is incredibly efficient and I get a lot back going down. Is it possible that there was a physical problem, brakes binding or something. Whenever you have an anomaly you should photograph all your energy consumption pages before you supercharge and they are wiped out...so it can be analyzed at a later time

I've had a few of these cases where the car's estimate of SoC at arrival at the next supercharger starts dropping precipitously a few miles after leaving a charger. This is especially worrisome driving in parts of Texas and Oklahoma because there are often long distances between superchargers with no bailout options. I've gotten into the habit of cross-checking the car using A Better Route Planner. ABRP tends to overestimate energy usage, so has been a safe alternative to the car's estimates. ABRP takes into account weather, traffic delays and what percentage of the speed limit you drive.

I often travel with a bicycle on a roof rack, when adds about 15% to the energy usage at interstate speeds. Although the car will adjust to this, it takes a number of miles so the initial charging plan is always overly ambitious. However, ABRP allows you to calibrate the energy usage to your driving and can have multiple profiles. So, I have a separate profile for when the bike is on the car that accounts for the increased energy usage.