opossum said:I'm not sure how relevant driving, charging and storage habits really are at this point. We seem to have heard from people with a wide variety of habits. I don't see his experience posted on this forum, but I know of another Phoenix area Leaf owner who lost a bar this month after about 16,000 miles... despite almost always charging to 80% in an air-conditioned garage, having covered parking at work, almost never fast charging (about three times in over a year), and certainly never running the battery pack dead. This guy was THE gold standard for vehicle care by Nissan's standards, and yet has roughly 15-20% loss as of this month...
TickTock said:My garage isn't air conditioned, but I got five stars across the board on my 1-year mandatory checkup so I am apparently not doing anything that Nissan anticipated would hurt battery life.
TomT said:I think that we have fairly conclusively determined at this point that the portion of the battery report that we get to see is of little value and is very rudimentary at best... The real data goes to Nissan and is for their eyes only...
opossum said:I'm not sure how relevant driving, charging and storage habits really are at this point. We seem to have heard from people with a wide variety of habits. I don't see his experience posted on this forum, but I know of another Phoenix area Leaf owner who lost a bar this month after about 16,000 miles... despite almost always charging to 80% in an air-conditioned garage, having covered parking at work, almost never fast charging (about three times in over a year), and certainly never running the battery pack dead. This guy was THE gold standard for vehicle care by Nissan's standards, and yet has roughly 15-20% loss as of this month...
Interesting, looks like we'll find out next year. Here is a complementary observation. The shop manual tells us that the first capacity bar corresponds to 15% battery capacity. The second bar is only 6.25%. The ratio of the two is: 6.25/15 = 0.4167. If your tech is right, this ratio would suggest that battery degradation growing with square root of time. The third capacity bar should take 1 1/2 years to turn off, instead of just one. The fourth bar two years, etc.LEAFfan said:opossum said:I'm not sure how relevant driving, charging and storage habits really are at this point. We seem to have heard from people with a wide variety of habits. I don't see his experience posted on this forum, but I know of another Phoenix area Leaf owner who lost a bar this month after about 16,000 miles... despite almost always charging to 80% in an air-conditioned garage, having covered parking at work, almost never fast charging (about three times in over a year), and certainly never running the battery pack dead. This guy was THE gold standard for vehicle care by Nissan's standards, and yet has roughly 15-20% loss as of this month...
+1! I whole heartily agree that it has nothing to do with charging (QC included), car color, or habits. Again, just recently, one of the ECOtality techs told me that he was told that drivers in the Phoenix area (not sure if Tucson is included) would experience a loss of a capacity bar every year or every 15K miles. Some people on here seem to despise these 'techs', but this sure sounds valid to me.
I agree that they seem to have little impact in hot climates like Phoenix where temperature effects dominated. That said, I don't think we should extrapolate that to the entire LEAF fleet, since degradation due to heat may not dominated in cooler areas.opossum said:I'm not sure how relevant driving, charging and storage habits really are at this point.
At first blush, that prediction seems unrealistic to me. But on further thought, I must admit that I have never seen a battery capacity degradation curve that started off with a 15% drop in year one. Most curves show the battery losing a lower and lower percentage of capacity each year and eventually leveling off into a more linear region. I suppose it's possible the big drops seen in Phoenix will be experienced by others over some larger number of years and they are now in the more linear portion of the curve. Even it that is so, 6.25%/year is a big number in my book.LEAFfan said:Again, just recently, one of the ECOtality techs told me that he was told that drivers in the Phoenix area (not sure if Tucson is included) would experience a loss of a capacity bar every year or every 15K miles. Some people on here seem to despise these 'techs', but this sure sounds valid to me.
+1RegGuheert said:At first blush, that prediction seems unrealistic to me. But on further thought, I must admit that I have never seen a battery capacity degradation curve that started off with a 15% drop in year one. Most curves show the battery losing a lower and lower percentage of capacity each year and eventually leveling off into a more linear region. I suppose it's possible the big drops seen in Phoenix will be experienced by others over some larger number of years and they are now in the more linear portion of the curve. Even it that is so, 6.25%/year is a big number in my book.LEAFfan said:Some people on here seem to despise these 'techs', but this sure sounds valid to me.
It sure doesn't sound like it. I suspect this is speculative. It's unlikely the curve would start out high then have a reduction in loss as time goes on with the same conditions.LEAFfan said:He said one lost bar per year, so that's 15% loss the first year, 6% more the 2nd year (21%), then another 6% the third year, etc. He knows the bars aren't linear.
RegGuheert said:I have never seen a battery capacity degradation curve that started off with a 15% drop in year one. Most curves show the battery losing a lower and lower percentage of capacity each year and eventually leveling off into a more linear region.
I have anticipated something linear as well, and I did not see a 15% drop coming in the first year. The only explanation I would have is that calendar life loss seems to be the dominant force. While cycling losses seem to increase linearly with time and the number of cycles, I believe that calendar life degradation increases with the square root of time.Ingineer said:I suspect the curve will be largely linear, Nissan only essentially made the first bar equal to 2 before loss shows, probably to stem off panic.
Correct. Note the mildly elevated temperature however. 25C or 77F would suggest that they wanted to either accelerate aging or tried to simulate harsher conditions. The NREL reports we looked earlier at determined that constant 28C or 82.4F was causing about the same level of calendar loss for their NCA cells as the climate in Phoenix would. Another thing worth noting is that the test cycle is more agressive as well: 2.5 to 4.2V compared with Leaf's 3.2 to 4.1V (turtle to full charge).Weatherman said:The graph shows cycle fade, which, from the model studies, would be expected to be more linear.
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