OrientExpress wrote:Of the current root-cause candidates for this issue, a software bug or a run of defective components, reputable highly-placed sources suggest that a software bug that is providing a corrupted data stream which is being used by various battery management subsystems which cause them to provide faulty indications is the leading candidate.
Actually, the data that we have so far from Nissan's own testing suggests that while over-reporting of capacity loss by the Leaf is a factor in some cases, that doesn't explain the bulk of the capacity loss. To quote from the Wiki section I have been working on:wiki/index.php?title=Battery,_Charging_System#Real_World_Battery_Capacity_Loss
"In late July, 2012, Nissan took 6 of the most severely affected Leafs with significant capacity loss to their Casa Grande testing facility in Arizona. One Leaf owner, Scott Yarosh, got his Leaf back with 3 capacity bars still missing (27.5% capacity loss), although Nissan removed the battery for bench testing and told him that he had only a 15% loss. Interestingly, he reported that Nissan had taken a total of 11 cars for testing. Another owner, Azdre/opossum were told that their Leaf has a 15% capacity loss, although the Leaf still showed 2 capacity bars missing (21.25% capacity loss). Their Leaf had the second best remaining capacity--the best was a 14% loss. A third owner, TickTock, got his car back with all 12 capacity bars restored. His testing suggested that he had not gained any capacity, but that a mis-calibrated sensor was reset and his Leaf now more accurately reports the actual capacity loss. He estimated that his real capacity loss was 15%, not 23%. Further testing showed that the value of a Gid (a unit of energy roughly equal to 80 watt-hours, named for Gary Giddings, who designed and built a meter to show battery state of charge) is apparently temperature dependent. Relying on the Gid-meter led to an inflated estimate of battery capacity loss. The entire thread can be read here.
The limited results available so far (8/8/12) from Nissan's testing suggest that part of the apparent capacity loss is due in some cases to the Leaf reporting a somewhat greater capacity loss than actually exists (6% greater in 2 cases, 12.5% greater in one case). However, all but one of the tested Leafs had at least a 15% loss of capacity, indicating that the problem is more than just incorrect reporting of the battery capacity. "
Again, feel free to make additions, corrections, or add data which contradicts this information. If you go to the Wiki, hyperlinks will direct you to the relevant post on the forum that the information is taken from.