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Discussion Starter #861
I did some more testing on my LTO cells.

This was from the same pack, half the cells were stored at 2.23 volts
The other half was stored at 2.14 volts.
Cells were stored like this for around 2 years.

The results were as follows. I ran the test on two different cells of each voltage, so 4 cells tested in total with the same numbers.
2.23 volts = 20.5 amp hours
2.14 volts = 20.6 amp hours

This means that, optimally so far, 2.14 volts would be the best storage voltage.

I really believe that 2.00 volts, and this is what I initially stored them out may have been the best storage voltage if not for them falling below 1.5 volts per cell. From my testing with Lithium Ion 18650 cells, storing at lower voltages was OK. I stored them at 2.9 volts with no issues. The 18650 cells did not have a BMS to drain the cells like the LTO cells have and that probably was the issue.

That all being said, I would recommend the 2.14 storage voltage as that would give you more than enough amp hours of capacity to prevent the cells from falling below 1.5 volts per cell. There is not that much difference between the 2.14 and 2.23 to probably matter. I will personally be storing them around 2.14 volts per cell.

If you are going to store them for 5+ years and never check them, and have the BMS on them, then you probably will want to store them at 2.23, which is about 50% capacity at that voltage.
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