For the optimal condition to store the battery when not in use for the long term:
-Store at ~50% of charge, check every few months.
-Store in low-temperature storage space ideally at 25°C/ 77°F
-Periodically use the battery every few months to keep the chemical in the battery moving.
*To read more resources about the battery cell type in your HyperJuice have: https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries