A lithium battery used only half of the electricity on the first day and then fully charged it. If it is still the next day, it will be charged in half, and it will be charged twice in total. This can only be counted as one charging cycle, not two. Therefore, it is usually possible to complete a cycle after several charges. Each time a charge cycle is completed, the amount of power is reduced a little. Lithium battery life will eventually need to be replaced.