Those are pretty cool batteries!
While I have no experience with them but I found this.
BU-702: How to Store Batteries â€“ Battery University
They say that they need to be stored at 40% capacity for long life and not 100% like lead acid.
"While lead acid must always be kept at full-charge during storage, nickel- and lithium-based chemistries should be stored at around a 40 percent state-of-charge (SoC). This minimizes age-related capacity loss while keeping the battery operational and allowing for some self-discharge."
"Finding the exact 40 percent SoC level to store Li-ion is less important that removing some charge and voltage serves as a handy fuel gauge indicator. At 40 percent charge, most Li-ion has an OCV of 3.82V/cell at room temperature.
To get the correct reading after a charge or discharge, rest the battery for 90 minutes before measurement. If this is not practical, overshoot the voltage on discharge or charge by 50mV. Discharge to 3.77V/cell or charge to 3.87V/cell, and the rubber band effect will settle the voltage at roughly 3.82V. Figure 1 shows the typical discharge voltage of a Li-ion battery."
How you do that is beyond me...
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