A 100% DOD cycle can reduce battery's impedance

[DaveEV]

I found this tidbit while reading on TMC:

You have to be careful on that. Calendar and cycling losses are not additive. The NREL battery degradation model (which has been matched to actual cell behavior of the same NCA chemistry) says to take which one is worse, but not to add the losses together. The reason for this is because cycling suppresses electrolyte film growth, which is the main cause of degradation from storage (see page 11 here):
http://www.nrel.gov/vehiclesandfuels/energystorage/pdfs/45048.pdf

Impedance normally directly correlates with capacity.

Anecdotal evidence with LEAF Spy typically shows a small bump in Ah and Health readings after a "100%" charge and I discharge to below to LBW, but this typically goes away within a couple days.

Anyway thought this was interesting and may provide for some discussion. Of course, the battery used in this study is not the same lithium chemistry as is used in the LEAF.

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[surfingslovak]

You have to be careful on that. Calendar and cycling losses are not additive.

Very neat! Thanks for sharing. That said, I disagree with stopcrazypp from the Tesla forum in this instance, since I believe that calendar and cycling losses were additive. Stoaty's aging model is based on an NREL study, which specifically calls this out. The fact that Stoaty has been able to fit this model to field data reported by dozens of owners within an acceptable error margin would seem to confirm the validity of this approach. To my knowledge, this has not been attempted on this scale before. Perhaps with lab data, yes, but not with data from the field. Much like what I said to RegGehueert, I don't mean to dismiss such opinions and reports. It's just if we want to give owners relevant and useful tools for battery life predictions, we have to focus on the big picture first, and then try to refine it by considering secondary and tertiary contributing factors. I'm not quite sure how to classify this, but I believe the statement about calendar and cycling losses to be incorrect.

 

[Stoaty]

If the calendar and cycling losses were not additive, Nissan wouldn't have been focused on how many miles per year the Arizona bar losers had driven. Recall that their 76% after 5 years "glide path" was based on the average 7500 miles per year that drivers in that area were putting on their vehicles (which of course was a post hoc rationalization).

 

[smkettner]

Is it even possible to discharge LEAF to this level? Is this VLBW, Turtle, or complete shut down?