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Anyway to estimate remaining lifecycle of a LiFePo4 (second hand)

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adriansantos

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I bought some second hand Sinopoly 3.2 100ah batteries (but sold as 90ah, marketing strategy). I found out is 100ah based on the model. Anyways tested the capacity and its >90ah, playing between 91-93ah, at least it is still >80% of 100ah.
But is there anyway to estimate remaining cycle for this batt, it was designed for 2000 cycles, i have no info from the buyer since they are just resellers.
Will internal resistance test mean anything, if yes, are there any table/info that can give estimates?1610465256231.png
 
No. But...

IR is always good to know.

I would assume the cell has about 1000 cycles on it based on cycle life and 90%+ rated capacity.
 
Cycle life (2000 cycles in your case) is usually rated to 80% capacity (or 80Ah in your case).

It’s not perfectly linear but if you are getting slightly over 90Ah now (meaning >90% capacity, you are probably about halfway to 80% of original rated capacity.

So you probably have another ~1000 cycles to go before capacity drops to 80Ah.

The end of life at 80% of original rated capacity is also somewhat arbitrary - the cells will continue to function past that point, just at ever-reducing capacity.
 
fafrd said:
Cycle life (2000 cycles in your case) is usually rated to 80% capacity (or 80Ah in your case).

It’s not perfectly linear but if you are getting slightly over 90Ah now (meaning >90% capacity, you are probably about halfway to 80% of original rated capacity.

So you probably have another ~1000 cycles to go before capacity drops to 80Ah.

The end of life at 80% of original rated capacity is also somewhat arbitrary - the cells will continue to function past that point, just at ever-reducing capacity.
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thats also my thinking on this. thanks
 
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