I don't understand why people only charge to 80%... One of the most important things is making sure the cells are properly balanced and this is true of all battery types.
I also don't understand why people make such a big deal about degradation, it's a fact of life with all battery types. It's a fact of life with a number of things. In the lighting world, the lumin output and loss is clearly identified on the packaging. With the Leaf, acceptable loss from the manufacturers stand point is clearly identified by the warranty. Nissan has no way to know how the end user will care for the battery, they must set a threshold to decide when to replace the battery.
The whole concept of battery degradation, failure rates and lifespans has been known for over a century, at least with lead acid batteries.
Expecting a perfect battery, with little or no loss is naive.
It had nothing to do with knowing not to depend on the warranty, that is frankly a stupid argument. It was knowing that I must consider the maximum rate of degradation that isn't covered by the warranty. That's called being an educated consumer without having unrealistic expectations of the manufacturer. If my battery degrades beyond the rate specified by Nissan, within the allotted time frame, they will replace it. It's simple math. I don't remember the numbers any more, but if Nissan says 35% degradation is acceptable by the end of my warranty and my battery has degraded 34%, I'm not going to complain or even attempt a warranty claim.
Batteries have a finite lifespan. They are a consumable. I've managed to get 15+ years out of one of my 12v AGM batteries, and barely 4 years out of another. The one that lasted 4 years sat the majority of its lifespan and gave up when I tried to press it into daily use. The 15+ year battery was used everyday from new and even managed to handle being in a car with no working voltage regulator. It was in a bad spot and the ground clamp would come off every time I did donuts and the voltage would spike to 20+VDC, but when it was hooked up would never go above 16VDC. It was an old clapped out Supra that I didn't care about. Suffice to say, Optima AGM batteries are the only ones I use now. I gave that battery away with that car, last I heard it's still in use. That's an exception though.
In terms of fleet maintenance, I replaced batteries every 3-5 years even if they still tested okay.
He also said that in testing it had traveled more than 300 mi on a circular track (I'm guessing indoor test track).
