Looking at a used Leaf, there are 10/12 bars which isn't bad ... but using LeafSpy SOH is 74%, and cells 1, 3, 5, 20, 24, 25, 27, 33,36, 39, 41, 43, 79, 81 and at least one more show up as "weak cells" during our short test drive. The pack wasn't fully charged before our test ride (LS says 94.6% SoC). Just how bad is this, anyone have any luck with taking a used leaf with such a pack to a dealer for a factory replacement or does the warranty only start kicking in at 8/12 bars or some such?

Sorry if this is a long since beaten to death, but as a new member my search priv has yet to be enabled

The capacity loss warranty is 8 bars and 5/60, so at 10 bars you're SOL unless there are individual cells dying. The primary battery warranty is 8/100, and if individual cells are causing imbalance, that's warrantable. However, "weak" doesn't mean unserviceable from a warranty standpoint. The LBC will throw codes for individual cells that are over-under charging beyond limits or have too low an internal resistance. If there aren't codes in the LBC, there's nothing to warranty.

Thanks, that's helpful. But I lack population data...how often do cells marked "weak" by leafspy turn into failures? That there are so many, combined with any one cell actually failing is "fatal" (turtle mode or worse) isn't it? Or am I misunderstanding the nature of the LEAF pack?

Yah, if you actually get a failed cell (especially a low-resistance issue) it will usually turtle the car. Nissan doesn't actually publish specs about how weak a cell needs to be before the LBC throws a code, I think simply because the algorithm for determining failure has so many factors involved. When Spy tells you "weak" I'm pretty sure it's using simpler criteria, just flagging the strongest and weakest cells, and every battery will have 10% or so of cells that are near the bottom of the barrel. We don't have a great many Leafs here in central Arkansas, but I can tell you I've only ever seen one Leaf battery with cell imbalance codes, and that was a '13 which would have been replaced anyway (it ended up getting the recall update to the later-style battery pack). Imbalance codes are very rare, even in batteries that are on their last legs.

LS can't just be marking all the relatively low cells, because in the six LEAFs I've test driven, only 1 has had multiple weak cells reported at a high SoC (and for test drives, unsurprisingly the sellers have the packs charged above 90% before I get there ;>).

I could easily imagine you could be right at steep discharged states ... that is where I'd expect to start seeing such warnings.

Well, seems like I need to steer clear of that vehicle, which is a shame as is otherwise better than the others I've been looking at (previously repaired hail damage and the like, so impaired ACV). But I'd still like someone with some insight into the LeafSpy internals/correlation with failure/replacement experience to enlighten me on how Nissan can give it a 10/12 (80+%), LS 74% AND to have so many "weak" cells at over 90% SoC. Seems like there ought to be something obviously wrong ... but darned if I guess without disassembling the pack and modules ... which no one in their right mind would let me do as part of a test drive (and given my two left thumbs, no one should allow me to do anyway ;>. I can analyze the data, but I ought not be the one taking it apart ... if we want it to go back together ;>).

Degradation and capacity loss happen, and it's kind of like telling someone who's buying a gas-fueled vehicle that they'll positively need to replace the engine in 10 years even if they do everything right. Just another reason EV's aren't ready for prime time and may never be.

Just another reason Cali and CARB are completely out of their minds, too... but that's for another thread in a different forum.