The QB-34 is a fast charger, 110/120 VAC for Quantum Battery 1/1+. It is the nature of all lead acid or gell cells to charge rapidly to about 3/4 power, then slowly to 100% charge. All "fast" chargers, regardless of make, require a long "topping off" time to charge from 3/4 to full charge. The only exception would be an unregulated charger or one capable of seriously overcharging a lead acid battery if left connected even 20 minutes too long.