Ill link a post i made about different Depth of Discharge amounts and the effects they can have on a battery. For instance a DoD of 10% from 100% to 90% is worse for the battery than a 10% DoD from 75% to 65%. Basically there is a lot to what helps keep a battery healthy and its complicated when you are doing small amounts of discharge and charging in a solar system. This is why most manufactures will give a certain statement like 7000 cycles at 80% DoD.
Hopefully this post and the one im linking can help you understand how battery cell chemistry is a very dynamic thing, and there many ways you can measure it, each one only giving a snapshot of the truth. I like to just think of the batteries as living things because of how complicated they are. How could you determine the health of a plant or a person? There are many ways you can measure it per-say, but the absolute truth will be difficult to know. But the more you understand about how health works, the better you can grasp whats really going on.
You could consider your 10% DoD a cycle, but you can do 10s of thousands of those cycles as opposed to just 7000 80% DoD cycles
I have a Growatt with 48V pack, LFP, using a Neey active balancer and Solar Assistant to provide data. Solar assistant will allow me to turn on/off Utility vs Solar/Battery/Utility based on the calculated state of charge of the battery. How low should the state of charge be allowed to go...
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