Jim Lewis
Well-known member
- First Name
- Jim
- Joined
- Jan 10, 2023
- Threads
- 39
- Messages
- 799
- Reaction score
- 671
- Location
- San Antonio, TX
- Vehicles
- Honda Accord 2017; 2023 Lariat ER
- Occupation
- Retired
If you high-mileage folks know your HVB SoH ~every 10K miles, it would be interesting to know how it declined vs. miles driven. Most BATTERY CAPACITY vs. MILES DRIVEN graphs I've seen for EVs show a slightly faster initial drop, then a more gradual loss of capacity. Here's an April 2023 article from InsideEVs showing the latest data then (Tesla's 2022 Impact Report) for the Tesla models S/X. That's NCA lithium-ion chemistry but, IIRC, ~the same holds for NCM chemistry.I think most importantly you guys should be sharing your battery condition! Mine is at 98.5% with 17k miles.
Source: Tesla: Battery Capacity Degradation Averages 12% After 200,000 Miles (insideevs.com)
P.S. For any of you thinking about the Standard Deviation depicted in the graph, don't take that as the standard deviation for placement of the remaining battery capacity of individual vehicles on the graph. That's probably the standard deviation of the mean battery capacity retained plotted on the graph for each plotted value of MILES DRIVEN. Usually, standard deviation of the mean is referred to as STANDARD ERROR. If s is the standard deviation for individual vehicle data, the standard error is s / sqrt(N), where N is the sample size used to determine the mean at any point. So, if the battery capacity of several hundred thousand vehicles were used to determine the mean points plotted in the graph, the standard deviation for individual vehicles might be significantly larger. Graphs I've seen where individual vehicle data points have been plotted around a "best fit" curve, such as shown in the above graph, usually have significantly more scatter in the remaining battery capacity for individual vehicles for any amount of miles driven.
The original source doesn't offer any details on how the graph was created and what "standard deviation" means: https://www.tesla.com/ns_videos/2022-tesla-impact-report.pdf#page=39 Actually, the source explains the steeper initial drop by saying the data for that is probably from vehicles that have been little driven and the decline you're seeing is simply from increasing age amongst ~sitting still vehicles. The authors suggest the slope further along the graph with increasing miles driven better reflects the effect of extensive driving (combined with age) on remaining battery capacity.
And it's marketing material!
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