[jauntywundrkind]

Lithium irons are often 4000 cycle now. For full cycles.

I forget who but I really want to say I was looking at some cells a year or three ago that were 10k cycle count.

And it's not like the battery is worthless at that point. It just means the battery is down to 80% max capacity. You can down cycle it, find some other consumer to use it, replace it, if you need the capacity. But should keep running for a long time.