Car battery charger QA 1: Can't reach the maximum charging current? To protect the battery, the system automatically identifies the battery voltage and selects the most appropriate current to charge the battery. When the battery voltage is low (for example, the 12V battery voltage is less than 11V), the system automatically charges the battery at the maximum current. (3 gears can adjust charging current, large current, fast charging) 2: The LifePO4 battery is not fully charged? When the battery is fully charged, it has a callback function, reducing the charge by about 1V-2V, which is normal. Added a small current after full charge uninterrupted charging. 3: Fan noise? It is normal that the fan has wind. Battery charger automotive parameters AC input :100v-240v~ 50/60 hz. Output voltage :12V / 24V. (normal - Max:13.2V-14.6V / 26.5V-29.2V). Lithium /LiFePO4/ lead acid (AGM,GEL,EFB, MF, Flooded, VRLA, SLA and wet battery..). Max: Lithium :12.4V-14.6V / 24.8V-29.2V. Lead acid :14.7V / 29.4V. LifePO4:14.6V / 29.2V. Output current :12V20A & 24V10A Support ah: 5AH-300AH... can have more capacity, the larger the capacity needs longer charging time. Minimum starting voltage > 2.0 V Power and load :MAX; 280W Size :158 x90x50mm(6.22 * 3.54 * 1.97 inches) .Net weight: 470g Note :1 Only charge the lithium battery with battery protection board(BMS). 2 Charge the battery below 15AH with the minimum current