We recommend recharging the lamps every 2 months and leaving for no more than 3 months without charging. Store the lamp in a dry and cool place preferably no higher than 25c, elevated temperature will increase permanent battery discharge rate.
This prevents the battery from dropping below 2.50V per cell, triggering sleep mode. Li-ion will no longer be recoverable if kept below 2.00V per cell for more than a week.