mod note:title changed from '15% battery degradation after 42k miles' as it seems to be a misunderstand of how to calculate battery degradation I have never given it much thought about my battery life. I figured that since I've only gone through 130, or so, cycles of my battery, I figured my degradation wouldn't really be noticeable. I have read articles on how little degradation there is on the model S, but I need to share my numbers because they are alarming. Below are the numbers I came up with on an excel spreadsheet of my kWh use today and my percentages. Below is taking into account the 5% buffer and is based on a 80 kWh battery. Battery Capacity (kW/h)85Battery Buffer (kW/h)5kW/h for 100% charge80Miles on my Tesla42,394August 31st 2015 Percentage at start91%Percentage after30%Percentage Used61%Total Energy Used kWh41.4Miles Driven124.2Average Energy (Wh/mi)33461% of 85 kWh battery48.8 my 61% use kWh41.4 At this rate, my full charge would be 67.9 kWh That is 85% battery capacity To sum up, my % of decline is .357% per 1,000 miles. I know there is a curve but this is very alarming. When I purchased the car, I was not told that I could lose 36% the battery life at 100,000 miles. If anyone has other numbers to contradict or agree, please share. I will continue to track the numbers and update.