Yet Another Degradation Thread (YADT): Battery age vs. use?

[Dolemite]

Probably an impossible/difficult question but... If one were to leave a Model 3 plugged in & sitting in a garage at room temperature, maintaining 50% charge, what would battery degradation look like in 10 or 20 years without any driving?

Asked another way: What % of battery degradation does age account for, vs. use? 1 vs. 99? 10 vs. 90? 30 vs. 70?

 

[KenC]

I'll guess deg at 50% indefinitely will be low, maybe not 1% low, but probably low single digits, low.

 

[Chisale]

I'll hazard a wild guess. The degradation from sitting in a climate controlled/shaded garage at 50% charge continuously supplied would be on the order of a couple tenths of a percent per year for the first 8-10 years. Then creeping up to 1-2% for the next several years after that before finally reaching a tipping point in the approx 20 year range where it starts increasing rapidly.
So, in other words, most the degradation we see would be from actual use until it gets much older than any current Tesla on the road.

 

[user212_nr]

I know people say "next to nothing", but if you leave anything unattended and unused they tend to break completely. Even if some of the components can be stored for 20 years, the system itself was not designed and tested for such a thing and the result is unexpected things happen.

In any case, the battery's "age" is measured by its use cycles and the depth of those cycles. We don't really have it down yet to a measurement that we can just look at like an odometer, not even close, but it is very common not to consider the age at all. Cars are judged by miles and airplanes are judged by the number of takeoffs and landings. The number of miles or hours isn't even necessarily counted.

When you talk about decades, corrosion is a major issue across all of the systems - electronics, wires, cells, screws, terminals, etc. An even bigger issue is the battery becoming outdated. In 20 years, we will probably be swimming in batteries. So age is a big factor, but not for the reason you mention.