Charging power (W) = voltage (V) * charging current (A). The selected AC charger or MPPT, PWM solar control charger is nominal A. For example, the battery is a 12.8V lithium iron phosphate battery; because there are two stages in the charging process (lead-acid has three stages), the first stage is called CC mode (constant current). When the battery voltage is lower than 14.6V, the charger will charge with the maximum current until when the battery voltage reaches 14.6V, it will switch to CV mode (constant voltage). At this time, the charger voltage remains unchanged at 14.6V, while the charging current naturally decreases, until the charging current drops to 10% of the rated charging current, the charging is completed. Note that unlike lead-acid batteries, lithium batteries do not require a floating charge function (FC). The floating charge will affect the number of cycles of lithium batteries.