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"Real-world data showed that Tesla battery degradation was less than 10% after over 160,000 miles (257,500 km)"

According to the graph there's a slight dip during the first 50k and then it levels out to a steady decline. There is no data for batteries around 60% capacity, since there are none yet :)

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I have some done some tests on 2900mAh Samsung cells from 2008. I have tested about 50 cells so far that were pretty abused, meaning they were discharged to less than 2.2V for several months. This is very bad as their normal operating range is 4.2-3.2V if you are really pushing them.

About half of the cells are effectively dead, internal shorts or electrolyte leaks. Included in this half are cells with mA discharge currents which is very out of spec. Not suitable for use.

The other half lived with an average capacity of 2050mAh with a std deviation of 150mAh. This is only a degradation of about 30% which was pretty surprising to me.

If you leave a lithium ion battery pack at a low level of charge for a long time, it will kill it. If you don't, it won't.

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