Since there isn't much else to talk about right now, I thought it would be an interesting exercise to predict and discuss the Model X range and battery capacity degradation over time. Given the fairly extensive research done on the Model S, and the average mileage driven for personal cars, we can make some predictions and assumptions. Many of the EV nay-sayers and FUD-spreading short sellers claim that the Tesla battery will need to be replaced sooner rather than later, and that this significant expense should be considered when purchasing the car (and when considering the overall environmental impact of the car).
Research suggests that the problem with battery degradation over time with Tesla's current generation battery packs is not as bleak as some would have you believe. If anyone has comments or finds a flaw in my math, please let me know.
Assumption 1: Model X battery pack will have similar performance to existing Model S battery pack.
We can assume that the Model X and S use the same cells and battery packs, and that performance of the 2015/2016 Model X will be similar to those in the 2012-2014 Model S. A fairly comprehensive owners survey in the Netherlands plotted out the actual range of several Model S cars, as reported by their owners over time. Based on these survey results, it appears that the Model S cars in the wild as of the beginning of 2015 (cars manufactured between 2012 and 2014) lose on average 6% in battery capacity/range after 50,000 miles. After that initial hit, it appears that range decreases at a much slower rate (1% per 30,000 miles). Again, these are averages with some cars performing better and some worse.
Assumption 2: Model X is driven close to the "average" of other cars.
It may be surprising to some that the average number of miles driven for a passenger car is only 11,244 miles per year (in the United States, data as of June, 2015). The calculations below use that average for estimates. But I'll include actual mileage numbers in the table as well in case people want to do the math for their own driving habits. For kilometer equivalents, you'll also have to do some math.
Could it really be true that a Model X would still have 84% of its range (215 miles) after 30 years of use and 337,000 miles driven? Data seem to suggest that. And this is good news for EVs in general, and Tesla in specific. Again, if anyone finds a flaw in my math, please let me know. Or share any other thoughts or observations.
References:
Tesla Model S Owner's Survey on range degradation over time: Tesla Model S battery degradation data | Steinbuch
Average miles driven per year by vehicle type (United States): Alternative Fuels Data Center: Maps and Data
Research suggests that the problem with battery degradation over time with Tesla's current generation battery packs is not as bleak as some would have you believe. If anyone has comments or finds a flaw in my math, please let me know.
Assumption 1: Model X battery pack will have similar performance to existing Model S battery pack.
We can assume that the Model X and S use the same cells and battery packs, and that performance of the 2015/2016 Model X will be similar to those in the 2012-2014 Model S. A fairly comprehensive owners survey in the Netherlands plotted out the actual range of several Model S cars, as reported by their owners over time. Based on these survey results, it appears that the Model S cars in the wild as of the beginning of 2015 (cars manufactured between 2012 and 2014) lose on average 6% in battery capacity/range after 50,000 miles. After that initial hit, it appears that range decreases at a much slower rate (1% per 30,000 miles). Again, these are averages with some cars performing better and some worse.
Assumption 2: Model X is driven close to the "average" of other cars.
It may be surprising to some that the average number of miles driven for a passenger car is only 11,244 miles per year (in the United States, data as of June, 2015). The calculations below use that average for estimates. But I'll include actual mileage numbers in the table as well in case people want to do the math for their own driving habits. For kilometer equivalents, you'll also have to do some math.
Could it really be true that a Model X would still have 84% of its range (215 miles) after 30 years of use and 337,000 miles driven? Data seem to suggest that. And this is good news for EVs in general, and Tesla in specific. Again, if anyone finds a flaw in my math, please let me know. Or share any other thoughts or observations.
Model X anticipated range loss over time. 90D with 257 miles (EPA) rated range | |||||
Year | Cumulative Miles Driven | Estimated Range (miles) | Range Lost (miles) | % Range Lost | % Range Retained |
0 | 0 | 257 | 0 | 0.00% | 100% |
1 | 11244 | 253.53235 | 3.46765 | 1.35% | 98.65% |
2 | 22488 | 250.0647 | 6.9353 | 2.70% | 97.30% |
3 | 33732 | 246.59705 | 10.40295 | 4.05% | 95.95% |
4 | 44976 | 243.1294 | 13.8706 | 5.40% | 94.60% |
5 | 56220 | 239.66175 | 17.33825 | 6.75% | 93.25% |
6 | 67464 | 238.70815 | 18.291854 | 7.12% | 92.88% |
7 | 78708 | 237.75454 | 19.245458 | 7.49% | 92.51% |
8 | 89952 | 236.80094 | 20.199062 | 7.86% | 92.14% |
9 | 101196 | 235.84733 | 21.152666 | 8.23% | 91.77% |
10 | 112440 | 234.89373 | 22.10627 | 8.60% | 91.40% |
11 | 123684 | 233.94013 | 23.059874 | 8.97% | 91.03% |
12 | 134928 | 232.98652 | 24.013478 | 9.34% | 90.66% |
13 | 146172 | 232.03292 | 24.967082 | 9.71% | 90.29% |
14 | 157416 | 231.07931 | 25.920686 | 10.09% | 89.91% |
15 | 168660 | 230.12571 | 26.87429 | 10.46% | 89.54% |
16 | 179904 | 229.17211 | 27.827894 | 10.83% | 89.17% |
17 | 191148 | 228.2185 | 28.781498 | 11.20% | 88.80% |
18 | 202392 | 227.2649 | 29.735102 | 11.57% | 88.43% |
19 | 213636 | 226.31129 | 30.688706 | 11.94% | 88.06% |
20 | 224880 | 225.35769 | 31.64231 | 12.31% | 87.69% |
21 | 236124 | 224.40409 | 32.595914 | 12.68% | 87.32% |
22 | 247368 | 223.45048 | 33.549518 | 13.05% | 86.95% |
23 | 258612 | 222.49688 | 34.503122 | 13.43% | 86.57% |
24 | 269856 | 221.54327 | 35.456726 | 13.80% | 86.20% |
25 | 281100 | 220.58967 | 36.41033 | 14.17% | 85.83% |
26 | 292344 | 219.63607 | 37.363934 | 14.54% | 85.46% |
27 | 303588 | 218.68246 | 38.317538 | 14.91% | 85.09% |
28 | 314832 | 217.72886 | 39.271142 | 15.28% | 84.72% |
29 | 326076 | 216.77525 | 40.224746 | 15.65% | 84.35% |
30 | 337320 | 215.82165 | 41.17835 | 16.02% | 83.98% |
Tesla Model S Owner's Survey on range degradation over time: Tesla Model S battery degradation data | Steinbuch
Average miles driven per year by vehicle type (United States): Alternative Fuels Data Center: Maps and Data