Do batteries degrade with age?

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I was wondering what the expected battery degradation may be over time?  I ask because I have a large yard...about an acre or more and would like to use the mower and other tools but am a bit worried about needing to have 4 or more batteries available to do the job.  

If the battery on average lasts 35 - 45 minutes when new, I am curious what that might become in 2 years, 5 years, 10 years, and ultimately when replacement would be necessary.   

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Posted 5 years ago

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Basing my opinion solely on this article:

It is comforting to think that the Nissan Leaf offers a guarantee of 70% capacity after 5 years and 60k miles. That's 12k miles per year, and for someone to do that they would be using the majority of the pack's capacity on an almost daily basis.

Since most people only cut their grass once a week or so, the life of lithium cells in Ego packs should exceed that handily. Though the cells in a Leaf likely have little in common with Ego pack cells...

Turn then to the Tesla data. Yes their packs are larger, and because of that their daily depletion will be less than the Leaf's, but Tesla uses 18650 cells, like the Ego packs do, so at least there may be some more similarity there... maybe.

For someone like me who uses only half the pack's capacity at a time, and only cuts once a week, I would expect the pack to last a very long time. For someone who depletes the pack completely every time they mow, and maybe more than once in the case of larger yards, the pack life will obviously be less.

The answer is out there, but since this stuff is just getting into the market it will be tough to tell for some time. Add to that the fact that things are constantly improving, and it's like hitting a moving target.

The electric car data is encouraging, where cells seem to be exceeding expectations.