Herm said:
edatoakrun said:
the key is that these are laptop cells and that implies a shorter life.. but if you only drive 40 miles a day with a 300 mile pack it will be cycled so gently that it may last much longer. Cost effective depends on how much Panasonic charges Tesla for them. The 3.4Ah cell has an energy density of 265wh/kg, and that is not quite twice the 150wh/kg that Nissan uses now.
I've been interested in this too. The 18650 cells they use in the roadster are only rated for around 300 cycles. But being the battery pack is so huge, if you only drove 40 miles per day on average, it would take about 6 years to actually cycle them 300 times.
I'm in the laptop business and I've even dabbled in battery refurbishment (replacing the cells in laptop battery packs) and I've come to the conclusion that a laptop cell when treated properly can last 6 years and still be able to hold most of its original charge. That assumes the number of cycles is low, but also that the battery has never been totally discharged for very long periods of time. However, once you start hitting 7 or 8 years, the batteries just start to drop like flies no matter what. So that would worry me with a Tesla considering how expensive their battery packs are. Of course, if I could afford a Tesla to begin with, then maybe it wouldn't bother me so much.
Anyway, the point is.. I have a sneaking suspicion that a 10-year-old Leaf will still have a much more reliable battery pack than a 10-year-old Tesla. I guess time will tell.