Li-ion batteries prefer to be stored around a 70% charge state, however this may be unrealistic for long term eBike battery storage. We recommend charging the battery completely, removing the charger, and storing in a safe climate controlled environment long term.
If your storage exceeds 3 months, we recommend topping off the battery in 3 month intervals. If your storage exceeds 6 months, we recommend cycling the battery (fully discharge it, then a full recharge) every 6 months. If you are unable to ride your bicycle to discharge the battery, you can flip the bike upside down, and tape the throttle to the full on position to drain the battery.
If you’re interested in Li-ion battery technology, check out this great resource! https://batteryuniversity.com/learn/