Did my dealer inadvertently hurt my battery?

[GDN]

Driving style can definitely impact the BMS as well. I drove a Tesla Model 3 for almost 4 years. I used Teslafi, which is an incredible service that tracks every mile driven along with charges, etc. The Ford API and data stream isn't good enough to be able to capture good stats.

However, my Model 3 when compared to about 70 other cars with the same number of miles was in the lower 10% of range being reported. I drove many very small drives 2 to 5 miles. Rarely had a long drive. My 310 mile rated car was down to about 270 miles max on a charge.

Following advice and research - I did two things. I would let the charge drop to about 10% before charging to about 93%. I did that for a few charges and I purposely got out and took a few 250 mile drives. This gave the battery and BMS a chance to recalculate and level out any anomalies in charges of cells. Within 2 weeks I had the range on my car back up to about 285.

When I returned to my short drives, the range started to drop right back down.

Drive and charge habits can definitely affect what the BMS sees and the health of your battery.

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[MickeyAO]

No, and I have huge respect for Mickey’s experience and guidance on this question. However, I have driven Teslas over 250k miles, had one of their earliest MS deliveries in 2012, had two full battery replacements in my 2012 car, spent a lot of time with their techs. Tesla has a built-in procedure in the BMS and MCU that runs a conditioning procedure that does exactly what I said to correct the BMS and recondition the pack when range “appears” to drop, recovering lost range. It isn’t really lost, but the BMS loses track over time, so needs to “see” the entire battery from time to time to know its status. The procedure is a documented Tesla service process that intentionally runs the battery under stress to near zero, and then charges its to 100%, and then does the cycle again. Tesla would not have this if it was bad for the battery.

This is the owner method:
https://help.tessie.com/article/78-calibrating-the-battery-management-system

There is a Tesla Service Center shop procedure method using a hidden menu on the Tesla MCU that firsts tests the battery’s health, then runs the cycling procedure, discussed here:
https://tesla-info.com/guide/tesla-bms-calibration.php

We are seeing this same phenomenon with the Lightning - the best way to have your truck reset the GOM is to do a full charge and the run to to as close to zero as possible, then fully charge again. It’s ability to project range is dramatically improved after doing this.

You should search for the SAE paper we published many years ago about the degradation in Telsa NCA (specifically Model S 18650s) cells when using the fast charging profile followed by an aggressive discharge profile. You might be surprised at how quickly they reached end-of-life conditions. Might explain why you had two battery replacements in the early Teslas.

 

[PungoteagueDave]

You should search for the SAE paper we published many years ago about the degradation in Telsa NCA (specifically Model S 18650s) cells when using the fast charging profile followed by an aggressive discharge profile. You might be surprised at how quickly they reached end-of-life conditions. Might explain why you had two battery replacements in the early Teslas.

I’ve read that paper, and my issues didn’t have anything to do with cell degradation - one was a blown contactor, before they had repair procedures, and the other was a BMS issue. I misspoke above - the replacements were on my 2014 Tesla - I had 50k on my 2012 S 85 when trading it in on a ‘14 P985D that needed a new battery at 75k and then again at 125k. In both cases I had lost under 5 miles range, and did a ton of road tripping with supercharging. Because Superchargers were so widely spread in those days, I often came in nearly empty, and frequently had to charge to 100%, but was always careful to never leave the battery at either extreme state for more than a few minutes. Tesla’s techs attributed my battery’s healthy sustained range to “running it hard and putting it away wet”, suggested that thrashing it high and low was why it always showed as new.

I had the same experience with the ‘19 MX that I traded on the Lightning in July (for more than I paid new) - in fact it hadn’t lost a single mile of its 325-mile indicated range in 48,000 miles, and had the same driving history - about 1/2 road trips with 100% charges to near zero, with the rest of the time being maintained at 80% with my two Tesla wall chargers set to 20-amp, relatively slow charging. I get that you are a technical subject expert on batteries and know way more than I do about this. My experience is obviously anecdotal, only 3 cars, informed by conversations with service techs and a lot of time on the Tesla forums, but it is my experience with those three Teslas and over 250k miles driving them with little range loss and no cell failure (and no actual pack failure considering it was non-battery issues that caused the replacements) that charging practices aren’t particularly important - as Elon says - just drive it and let it manage itself. Plug it in every day, don’t fully charge unless needed, don’t leave it fully charged, and only run to empty sparingly. Be judicious in using DCFC because that creates heat and wear, but use that too when needed - it is only a thing. And at least in my case, I saw little to no impact from using my vehicles in the widest possible range of battery extremes - cold, hot, empty, full, fast charge, slow charge, etc. What I would NOT do is stay in the middle of the pack’s range forever, never pushing the top and bottom, never exercising its charging speed ranges. That which is not used is lost.

 

[Jim Lewis]

We should all hope the Ford Lightning battery does as well as the Tesla Model S batteries. This is an owner-self-reported study (I wonder what @MickeyAO thinks of the results-whether they're for real?).

Source: https://maartensteinbuch.com/2015/01/24/tesla-model-s-battery-degradation-data/

The owners' data is tabulated in the following Google Sheets spreadsheet with self-reporting of each owner's charging lifestyle.

Tesla Battery Survery - Google Sheets (text version of the link is:

The following seems a rather tempered summary of real-life experience with EVs and how best to treat your vehicle's battery to be one of the scatter points above the trendline instead of below it.

(the date of the article seems to be from about 2020, as the most ancient comments are 3 years old).

How Long Should An Electric Car’s Battery Last? (myev.com)

and Renault's advice:

How long does an electric car battery last - Renault Group

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