Data over a few thousand miles

[ILLCOMM]

I wrote a Google Script to pull data from my MS (75D) every hour (using the API) and dump it into a Google Sheet. Of course that makes charting really simple. Finally got around to playing with the data and thought it was mildly interesting, enough so to share. Takeaways:

1. max range does gradually decline over time, and
2. average efficiency (in Wh/mi) is north of 300 which makes it hard to achieve rated range (which I believe is calculated at 280 Wh/mi)

I think if I knew these things at purchase I would have gone with the 100D as I semi-frequently make a ~220mi trip which can get dicey given the above.

NB: I usually charge to 70% which you can see in the top-left chart.

 

[TexasEV]

Max REPORTED range is decreasing over time, but the data doesn’t tell you if it’s a real range decrease or if the algorithm that estimates state of charge is becoming less accurate over time. If you only charge to 70% I suspect the latter.

 

[ILLCOMM]

Max REPORTED range is decreasing over time, but the data doesn’t tell you if it’s a real range decrease or if the algorithm that estimates state of charge is becoming less accurate over time. If you only charge to 70% I suspect the latter.

About once a month I charge to 100%.

I thought charging to a lower max (e.g., 70%) was good for the battery in the long run. It that not correct?

 

[TexasEV]

About once a month I charge to 100%.

I thought charging to a lower max (e.g., 70%) was good for the battery in the long run. It that not correct?

What’s “good for the battery” and what gives the most accurate state of charge estimate are two different things. While charging to only 70% may theoretically be better for battery longevity, and lab tests may show a statistically significant difference, as a practical matter many years of Model S use has shown no meaningful difference. Remember the early Model S firmware only let you choose charge level of 92% or 100%— the slider came about because of misguided EPA policy on how range was advertised.