We recommend charging the internal battery of the Lithium booster immediately after purchase, every 30 days and after every use. By frequently charging the battery, you maximize the power potential of the unit, and ensure that whenever you need it, the unit will be ready. Keeping the battery fully charged also vastly extends the life of the unit. In any case, it is important to keep the power at least above 60% and must better above 85% as noted in the manual instruction.