It’s not my assertion, it’sTesla’s. The owners manual, in addition to recommending to LEAVE YOUR VEHICLE PLUGGED IN (Tesla’s upper case, not mine), says “There is no advantage to waiting until the battery level is low before charging. In fact, the battery performs best when charged regularly”.
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Model 3 Performance Battery Degradation One Month (Story)
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I was referring to the fact that many technicians claim driving history is taken into account when calculating rated range while institutional knowledge here says otherwise.
favo
P3D+ owner
Did my second 100% charge yesterday (up from about 70%). I got 296 miles again, so no improvement. Other than twice charging to 100%, I have always charged to 90% (generally every day). I have never supercharged. 1666 miles on the car.
I agree with that. Sometimes the techs know less than the aficionados and owners.
I don't disagree the manual says that. But tesla's expert says otherwise, and Tesloop is an example of a lot of battery cycling being ok.
Jedi2155
Model 3 has Arrived.
Ambient temperature has a big impact on charge capacity so I'm wondering on how that is impacting your car. Whats your build date and charge rate? My personal results are 306 miles (as of Sunday) via a supercharger ~2700 miles, August build. Approx. 80% of my charges have been superchargers. See my post here about battery capacity.
One nice thing about superchargers is that they heat up the battery a lot allowing it to take a bigger charge than home charging. The downside is the obvious wear and tear .
In regards to the 90% charge, I'd personally use 80% and just let go down a little lower daily unless you really need that extra range. 80% is the sweet spot between maximum longevity and capacity.
favo
P3D+ owner
My details are in my sig. (P3D+ VIN 554xx built 7/21/18, delivered 8/28/18, if you're on mobile). I charge at 32A from a NEMA 14-50.
Re: charge rate recommendations, the "70% charge rate is optimal" statement by Jeff Dahn preceded the 2170 batteries, as far as I know. There were some (at least minor) chemistry changes, not to mention the form factor change and various changes in the pack. Not sure if we can take Dahn's 70% as gospel for the Model 3. Elon's tweet about 80% to 30% SOC range being good for the battery was from 2014. Recent reports in this thread say to charge to 90% to allow BMS to better calibrate pack capacity. And of course the manual just says leave it plugged in. Not so straightforward to know what's best.
I've heard a number of folks say 100% charge takes a long time. What amps are you charging at? On my HPWC the charging will slow down the last few percent but not nearly what you describe.
Stretch2727
Engineer and Car Nut
A few weeks back I had a lot of worries about battery degradation on my model 3. The car was only charging to about 280 miles which is almost 10% loss. Even had the service center check the car when it was in for other service but they said everything was ok. I have a very short commute of 12 miles and was charging everyday.
Some things I have learned.
The miles reading is based on calculated battery capacity only. It does not vary with driving style or temperature.
It appears the Tesla BMS (Battery Management System) will loose some calibration if you are shallow charging.
The analogy I would use is if you are trying to find the capacity of a bucket that hold 5 gallons (20 quarts) only using 1 quart of water. If you only add a quart and measure the height change to estimate the capacity any error in the height measurement is multiplied by 20. If you use 2 gallons to estimate the total capacity any error is multiplied only 2.5 times. This is greatly over simplifying but explains what I believe is going on. This is why shallow charging leads to these errors.
The charging cycle allows the BMS to measure the energy (water) going into the battery with the change in the overall voltage (height) of the battery to estimate capacity. My guess is the Tesla BMS errors to the low side to be sure the actual range is never underestimated.
I have been following advice I saw to only charge when you are below 100 miles. I am charging to 80%. So now most cycles are about 30% to 80%. The extrapolated charge is back to 308 miles with 247 miles of charge at 80%. I charged one time to 100% @ 307 miles. It took a few cycles to have it correct. The car has almost 7K miles.
Hope this helps anyone concerned about the battery capacity.
Some things I have learned.
The miles reading is based on calculated battery capacity only. It does not vary with driving style or temperature.
It appears the Tesla BMS (Battery Management System) will loose some calibration if you are shallow charging.
The analogy I would use is if you are trying to find the capacity of a bucket that hold 5 gallons (20 quarts) only using 1 quart of water. If you only add a quart and measure the height change to estimate the capacity any error in the height measurement is multiplied by 20. If you use 2 gallons to estimate the total capacity any error is multiplied only 2.5 times. This is greatly over simplifying but explains what I believe is going on. This is why shallow charging leads to these errors.
The charging cycle allows the BMS to measure the energy (water) going into the battery with the change in the overall voltage (height) of the battery to estimate capacity. My guess is the Tesla BMS errors to the low side to be sure the actual range is never underestimated.
I have been following advice I saw to only charge when you are below 100 miles. I am charging to 80%. So now most cycles are about 30% to 80%. The extrapolated charge is back to 308 miles with 247 miles of charge at 80%. I charged one time to 100% @ 307 miles. It took a few cycles to have it correct. The car has almost 7K miles.
Hope this helps anyone concerned about the battery capacity.
The statement about temperature is misleading, or rather incomplete. I think what you mean is that rated range doesn’t take into account that the car uses more energy in the cold, so it has less range (cold air is denser so it takes more energy to overcome air resistance, tires have different friction in cold, etc.). However rated range is IS lower in the cold because batteries have less capacity in the cold. So when you say rated range is based on battery capacity only, that is true, including the fact that cold batteries have less capacity so a lower rated range will be reported. This is why Teslas have always shown lower range in winter than in summer, and every year starting in the fall we see new owners in cold states posting wondering why their car has lost range.
Mine has 6,600 miles currently, and charging to 90% every day for over a week has been giving me an extrapolated 100% charge level of around 295 lately (down from around 300 that I was getting initially when charging to 90%). That's better than the 288-ish I was getting when I was charging to 75% or so regularly, but still a little bit too bad that it's below 300 miles. Ambient temperature that might affect capacity hasn't been an issue, either, around here in the SF Bay Area, where we've had an uncommonly warm fall in the parts I inhabit (as in 75 - 85 Degree highs virtually every single day for a long time).
Last thing I'll try, is the let-it-go-down-to-30% plan you describe above, charging only when the car gets down to 100 miles, and then fill it to 80%. The only thing I don't like about this approach is that it goes against Tesla's advice to keep the car plugged in every day, which you can't do, at least not on the days you're getting close to that 30% level (Since the lowest I can set the charge limit to, is 50%). Still, there might be a happy medium if I set the charge limit to 50% (which should result in a plugged in car but no charging on days it's actually above 50%), and then set it to not charge at all once it goes below that level, until 30% is hit (then charge to 80%).
In the end, I just want to do this sort of test (before it gets cold) just to verify I've got appropriate capacity, after accounting for some amount of actual degradation. One reading in the 305 range would be nice before we head in to the "cold" months of 40-ish degree weather . . . . we'll see.
Stretch2727
Engineer and Car Nut
Yes agreed, the range is lower in the cold but the battery capacity is not effected by the cold. So the miles displayed should not change due to temp.
Stretch2727
Engineer and Car Nut
Yes agreed is better for the battery to charge every day to some lower 60-80% level. It does throw off the calibration if you not driving very far each day. Once you are comfortable you do not have any degradation by charging 30-80% you can go back to charging every day knowing it will throw off the calibration of the BMS. The capacity will be there even for a long trip.
Could not find a way to edit the post I wanted to say that for this last charge to 100% where it only went to 99% I took it down to 19%.
I am starting to think that some of our batteries have some bad cells. Reason is I see ppl with 10-15k+ posting over 300 miles range with 100% and 275 with 90%. So I think it boils down to some of us have more bad cells then others. The guy that started this thread says he got a new battery and there are plenty of post here with similar reading to his. That would mean that some of us especially the guys with less are candidates to at least ask for a new battery and see what happens.
I am starting to think that some of our batteries have some bad cells. Reason is I see ppl with 10-15k+ posting over 300 miles range with 100% and 275 with 90%. So I think it boils down to some of us have more bad cells then others. The guy that started this thread says he got a new battery and there are plenty of post here with similar reading to his. That would mean that some of us especially the guys with less are candidates to at least ask for a new battery and see what happens.
I wish I was using TeslaFI from day one but as I remember at 1500 miles I was still at 279 for 90%.
Now as you can see I am hovering just above 270 for 90% it is a little disappointing to see the loss. I mean sure we all know some is normal but I guess we expect it later on not up front. That is what I like about tracking every datapoint with TeslaFi you have actual data history and you can download to Excel if you like. Not trying to see anyone on it but sure does make tracking everything about the car easy. I am amazed that the trip data is so accurate that you can see the exact parking spot you parked in for every trip kinda insane.
In any case maybe the starter of this thread is right if you think something is wrong get it checked out. For me I'm tracking the date points and seeing where it goes. As you can see from my data in a month i have gone from est 100% of 304 to 302 with about 1700 miles driven in that time. Let's see if it levels off or keeps going. I do find it odd that I cannot charge to 100% and even lately the 90% fall short to 89%. But like I said the value of logged data.
Sorry but that’s just not correct. All batteries have lower capacity in the cold. Here’s one of many explanations you can find about it:
Discharging at High and Low Temperatures
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