The Panasonic (Tesla) battery system degradation

Tesla Model S battery degradation data.

Author: Maarten Steinbuch , professor in Systems- and Control at Eindhoven University of Technology (TU/e).

Updated: April 14, 2018.  Tesla Motors provides an 8-year infinite mile battery failure warranty but it doesn’t cover degradation. Therefore it is highly relevant for every Tesla driver to know what to expect of the degradation of the capacity over time, because it is equivalent to the range of your car. In the Netherlands, Merijn Coumans is updating on a regular basis, via theDutch-Belgium Tesla Forum,  a file of owners’ data, created by Matteo. The most recent (Apr 23, 2018) version of the results is displayed below. Detailed explanations are also in the google doc file, as well as at the end of this blogpost. The new files also have data input possibilities for USA and other non-km (i.e. miles) drivers.

1In the figure the percentage of range loss is shown on the vertical axis. The horizontal axis displays the distance (in km) driven with the vehicles.

The red fitted line has a slope above 60.000 km (say 40,000 miles) of 1% per 50.000 km (30,000 miles). On average the batteries have 91% remaining at 270.000 km (170,000 miles). If the linear behavior would continue, then the ‘lifetime’ (still 80% capacity left) can be calculated as follows: 91-80 = 11% times 50.000 km =  550.000 km, plus 270.000 km, gives 820.000 km (510,000 miles)! Note that a ICE car has a average lifetime of 220.000 km (140,000 miles)… And remember: if an ICE fails after say 300.000 km, you have a problem. The battery in a Tesla EV after the suggested 820.000 km (ok, lets take 500.000 km, still great!) still has 80% capacity left!

To put in into perspective, on a 0-100% scale, it looks like this:

2Here is a nice video introducing an interactive graph from Teslanomics

The way to measure this is to do a full charge (100%) and then check the EPA rated range (in North America) or Typical range (in Europe and Asia/Pacific). In the plot, these numbers are then compared to the range numbers the car displayed when it was new. For example, for the 85 kWh Model S85 variant, this is about 400 km typical range or 265 mi EPA rated range. Even though this is mostly a reliable method, sometimes the computer in the car can’t accurately estimate how much energy the battery holds and might display an inaccurate range number. To improve accuracy, it is a good idea to run down the battery to almost empty and then charge to 100%, once a month. This is known as rebalancing the battery. However, the battery shouldn’t be left at 0% or 100% for more than 2 hours.

The data collected by Merijn, also include how many Supercharger visits were done, among other details. See the forum for more information, or if you want to upload your data.

Besides Mileage vs Remaining Range, the file includes two other charts: Charge Cycles vs Remaining Range and Battery Age vs Remaining Range. From literature and research we know typically that 80% of battery capacity remains after 1000-2000 full cycles, strongly dependent on the temperature of the batteries. The data below support these numbers.

3

4

Here is a recent update from the USA with almost 130000 miles driven as max.

tesla-battery-degredation-pluginFrom the USA+ drivers I could find the following previous data of the Plug in America Survey, and used it to generate the following picture:

PlugInAmericaData

I compared all provided data with the EPA 265 miles number for the 85kWh Model S and to the 210 miles EPA number for the 60 kWh models. It is not clear of course how trustworthy this data is, and how peoples measured..

If you like the km version, here it is:

PlugInAmericaDatakm

The plot below is from UK-manufactured Nissan Leafs, 2013 24kWh models, thanks to  forum users and via Simon Canfer.c563dltxqaa_ik6-jpg-large

Links on battery degradation:

Here are some plots from 2013

From a Tesla Blogger

A nice video on battery degradation can be found here.

How to prolong Lithium-based batteries?

Some data from 2013 from the Tesla Forum

Here is a very nice report on the Tesla Roadster by Plug-in America, one result is the following one, based on 126 vehicles:

roadster

Source (read more): https://steinbuch.wordpress.com/2015/01/24/tesla-model-s-battery-degradation-data/