johnlocke said:
If you plan to keep your car for 10 years better plan on at least one battery replacement out of your pocket(currently $8400 with exchange) unless you can live with 50% capacity.
When we're talking about battery life, please avoid exaggeration.
Either the battery degrades more than 20% in 8 years, or it doesn't. If it degrades slower, the worst case is that you hit 80% one day outside warranty, or just under 2.5% loss per year. After 10 years, you'd still have 75% SOH (not 50%).
If it degrades faster that 2.5% per year, then you will have a battery replaced under warranty before 8 years. If the initial battery was replaced after 4 years and 1 day (5% degradation per year), then the replacement battery may reach 80% after 8 years and 2 days (2 days out of warranty). At 5% loss per year, after an additional 2 years, you'd be down to 70% (not 50%).
If there were a group of customers needing
two battery replacements under warranty, the worst-case would be 7.5% loss per year, such that the 3rd battery reaches 80% one day outside the 8-year warranty. In that case, after 10 years, the car has 65% SOH, not 50%.
For a customer with 3 replacements under warranty, worst-case has the 4th pack reaching 80% 1 day outside 8 years (10% loss per year). After ten years, you'd have 60%, not 50%.
Since actual loss is not linear, I could believe that customers who degraded to 80% in 2 years might degrade to 50% in 2 more years. But I believe the percentage of 30kwhr owners getting a new pack every 24 months is small (even before the firmware correction). The comment "if you plan to keep your car for 10 years... live with 50%" implies that 50% after 10 years is the general case. I don't see how that statement can possibly be accurate.