How do you guys calculate your full rated miles short of charging the battery completely? I had my "Trip" meter on (that always shows current battery in percentage) and changed the setting to show the rated miles on the instrument panel. As soon as the percentage changed on my Trip meter, I noted the rated miles on the instrument panel and did the simple math to get total rated miles. 150 miles with 62% battery gives me 241.9 rated miles (150*100/62), about 3% degradation (S75 at 249 rated miles) with only about 680 miles (in 2 weeks) on the car. Is this a reliable way to get actual battery capacity and degradation? Is my degradation normal?