In late 2010, I did a small, informal survey of Roadster owners in the Northwest to get some idea of how our battery packs were holding up. The top-level result was that we were seeing very little degradation, with small variations between packs being a larger effect than capacity loss from use. When the controversy with LEAF battery pack degradation in hot-weather climates emerged last year, I did broad survey of LEAF owners and shed enough light on the subject that Nissan's Andy Palmer recently encouraged every LEAF owner to read the survey results paper. Now, I'd like to return to the Roadster and do a more thorough study across the full Roadster owner base. My goal is to find answers to questions like these: How does the Roadster battery pack hold up over time and miles? How does our battery pack degradation compare to Tesla's original guidance that the our packs will have 70% to 80% of original capacity after 7 years or 100,000 miles? How well does the Roadster's active thermal management protect the battery pack against hot and cold weather? How do version 1.5, 2.0 and 2.5 Roadsters compare in battery longevity and major maintenance? What about Roadster vs Roadster Sport? How many Roadster owners have had major drivetrain component replacements? Now that the factory warranties are ending on more and more Roadsters, what would the value proposition be for an extended warranty? I hope this will be a valuable community resource in both the near future and long term. Contribute to the Study I invite all Roadster owners to participate in this study. I takes just a few minutes to fill out the survey form, available here: Plug In America Roadster Survey Form The survey asks for your name, email and VIN sequence number, but keeps those fields private. Your private contact info will not be used for any purpose other than the survey. Except for those private fields, all of the survey data will be available for others to examine and analyze. After you've filled out the form once, there's an update form you can use to correct or add a value, or to do an update with newer info, without filling in the values that haven't changed. Submit as often as you like, records are grouped by vehicle so there's no problem with having multiple reports on the same vehicle. Results Released at Teslive, July 13th, 2013 I released results from the Roadster Battery study, using data collected from the survey and via OVMS. A quick summary of the major results: The projections from the various data sets studied suggest that Roadster batteries will be at 80% to 85% capacity after 100,000 miles, on average. Stated another way, the study shows an average loss of about 3.7 ideal miles of range (1.6%) per 10,000 miles driven. As there is considerable variation among vehicles with similar mileage, an individual owner’s experience may vary significantly from the average. The survey found no significant correlation between climate and battery pack longevity. Individual experience may vary. The survey data for high-mileage vehicles is sparse with little variation in climate among those vehicles, so it’s possible an effect from climate will emerge as more data is collected. The survey found no significant correlation between vehicle age and battery pack longevity, although the study has no data on the first year of use, nor use beyond 4.5 years. The full paper with more detail is here: Plug In America Roadster Battery Study Results Paper For an overview of the data showing survey participants by geographical area visit this page: Survey Results page. The Vehicles List page shows an abbreviated table of the survey data, sortable by various criteria, which provides an easy way to examine some of the most interesting information collected. The full survey data is available for download in tab-delimited test and JSON formats, see the Results page for the links.