We are all concerned with battery degradation. How does the battery age over time and use. Being at 94,000 miles after 2.5 years I thought I share my findings here to give everyone an idea what to expect.
I have been keeping track of my rated range over time and wrote down the numbers. I've also added my car to a battery survey regularly (MaxRange Tesla Battery Survey). Later I started using a tool that looks at the CAN bus data and displays the available capacity in kWh. This is not available through the normal UI.
How much has my battery lost in those 2.5 years and driving 94k miles: aprox 21 miles. When brand new, it had 271 miles, now it's 250 miles when fully charged. That would be 7.75% loss. Not too bad, but this is only half the truth. Looking at the data I and other have collected, it shows that degradation starts 'fast' and then slows down and it seems to flatten out.
Here is a screen shot from the mentioned Tesla battery survey. The blue dots are all entries, the pink dots are my entries. What's interesting is how the battery loses capacity quickly at the beginning and then the curves becomes pretty much a flat line. It seems that after an initial drop in capacity the batteries are holding up extremely well without loosing additional capacity. My data shows I have not lost any capacity in the last 30-40k miles.
Here are screenshots of the app that shows the actual usable capacity reported from the car. The one on the right is when I started using the app at 70k miles in April '16. The usable capacity shows 73.4 kWh. In November '16 at 94k miles it shows 73.6 kWh. Technically it went up a little but small variations are normal and due to other factors.
A little more info about my car. I obviously drive a lot.
About 40k miles I have driven on road trips only charging at Superchargers. Aprox 500 times have I charged on a Supercharger.
I live in Orange County, CA which has a pretty high average temperature.
Many trips were around Arizona and Nevada where the temperatures are very high.
My lifetime energy usage is 320 Wh/mile
I usually charge to 80% daily and about twice a month (on average) I charge to 100%.
I have charging set to 2 am at night.
On road trips I regularly drive the battery down to less than 10 miles.
About 6 times have I driven the car beyond 0 miles.
Conclusion:
- Degradation appears to be fast in the beginning and then slows down significantly and seems to almost be non existing after the first 50k miles.
- Frequent Supercharging doesn't seems to hurt the battery.
- Hot ambient temperatures don't seem to hurt the battery as much as I thought.
- using the full capacity (charging to 100% and driving all the way to almost zero) doesn't seem to hurt much.
- Tesla is keeping the battery very healthy no matter what I do.
- My car is and 'old' 85 with the old cells. I assume the new cells (70/75/90/100) are better in terms of degradation.
I have been keeping track of my rated range over time and wrote down the numbers. I've also added my car to a battery survey regularly (MaxRange Tesla Battery Survey). Later I started using a tool that looks at the CAN bus data and displays the available capacity in kWh. This is not available through the normal UI.
How much has my battery lost in those 2.5 years and driving 94k miles: aprox 21 miles. When brand new, it had 271 miles, now it's 250 miles when fully charged. That would be 7.75% loss. Not too bad, but this is only half the truth. Looking at the data I and other have collected, it shows that degradation starts 'fast' and then slows down and it seems to flatten out.
Here is a screen shot from the mentioned Tesla battery survey. The blue dots are all entries, the pink dots are my entries. What's interesting is how the battery loses capacity quickly at the beginning and then the curves becomes pretty much a flat line. It seems that after an initial drop in capacity the batteries are holding up extremely well without loosing additional capacity. My data shows I have not lost any capacity in the last 30-40k miles.
Here are screenshots of the app that shows the actual usable capacity reported from the car. The one on the right is when I started using the app at 70k miles in April '16. The usable capacity shows 73.4 kWh. In November '16 at 94k miles it shows 73.6 kWh. Technically it went up a little but small variations are normal and due to other factors.
A little more info about my car. I obviously drive a lot.
About 40k miles I have driven on road trips only charging at Superchargers. Aprox 500 times have I charged on a Supercharger.
I live in Orange County, CA which has a pretty high average temperature.
Many trips were around Arizona and Nevada where the temperatures are very high.
My lifetime energy usage is 320 Wh/mile
I usually charge to 80% daily and about twice a month (on average) I charge to 100%.
I have charging set to 2 am at night.
On road trips I regularly drive the battery down to less than 10 miles.
About 6 times have I driven the car beyond 0 miles.
Conclusion:
- Degradation appears to be fast in the beginning and then slows down significantly and seems to almost be non existing after the first 50k miles.
- Frequent Supercharging doesn't seems to hurt the battery.
- Hot ambient temperatures don't seem to hurt the battery as much as I thought.
- using the full capacity (charging to 100% and driving all the way to almost zero) doesn't seem to hurt much.
- Tesla is keeping the battery very healthy no matter what I do.
- My car is and 'old' 85 with the old cells. I assume the new cells (70/75/90/100) are better in terms of degradation.
