Graph battery capacity (ending range) over time at given charge level

mkolowich 7 years ago updated by James 6 years ago 13 1 duplicate

One of the most important things for an EV owner to understand over time is how the battery range at, say, 90% charge declines over the lifetime of the battery.

I would like to see a graph for any given completed charge level (e.g. all 90% charges) that shows the ending range for each charge for that level. There should be a choice for x-axis of:

  • Odometer reading
  • Date
  • Charge number

Also, it may be useful to allow smoothing to make the chart more readable (I.e. average last 3 charges)

Duplicates 1

James --

I appreciate the changes you just pushed out: x-axis as odometer rather than date, and ability to define the trend line.  Nice job -- this is one of the most useful reports yet!




That is amazing!  Here is mine for an MX 90D over the better part of two years:

A couple of observations:

1.) my impression is that the best independent variable is mileage rather than time: would it be difficult to make the x-axis switchable to odometer rather that date?  That said, both are helpful; and 

2.) what I’ve read suggests that the trend line is a curve rather than a straight line, with degradation diminishing over time, and my chart certainly suggests that degradation is not, in fact, linear: most of the early points are below the line and most of the later points are below the line.  Or is the trend line simply drawn from first point to last point?  It would be neat to figure out the trend line curve, so that degradation could be predicted into the future, based on the curve!

In any event, great job on this — this is hugely useful.



Great job!

By the way I have the impression that the filter on "Include Completed Charges Greater Or Equal To: " is not taken into account.

If I put 100, I'd expect to only see 30 dots (the number of 100% charges I ever did) but I see much more.

Thanks.  I found the error.  It wasn't working correctly when filtering 100% charges.


I concur with your observation.  Changing the “include charges greater than or equal to” number does not change the graph for me either, nor the list of included data points.

Under review

How about something like this - https://www.teslafi.com/battery.php

It might take a minute to run the first time.  I had to clear out all of the cached data.

For those who don't know, this graph already exists:


Having said this, I would like Teslafi implementing it as well, but with actual measured data. It would be more precise and the deviation in the dots that we see in the chart above would be very limited.


On the TMC Forum there are a couple threads asking "What is your 90%".  There appears to be a lot of interest.  It appears a lot of people are getting 7 miles short of the EPA when charging to 80% or 90% (prorated).  I think if this information was provided it would be an ideal statistic.  Besides knowing what my car is doing the second most important part is how is my car doing compared to the fleet.  I.E. Do I have a problem with my car.  Having a NEW Car that is 7 miles short had me worried that my battery has already degraded.

I would like to see my car/battery compared against the fleet (i.e. similar Car/battery) too 


I'd really like this

I am very interested in this.  I actually just started another thread not knowing about this one to show the ending Rated Range on the Charge line but some history graph and details numbers would be nice.  I also like the comparison of the fleet which might help to determine if a car is having a problem.


Great request! I was wondering if there is a chance of adding some TeslaFi fleet statistics (anonymized of course) broken out by model/battery/odometer range. Perhaps with a calculation of estimated degradation? Maybe add the fleet stats to the graph as a comparable?