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.The QB-34, QB-37 & QT-47 are Regulated fast chargers, which will not overcharge the battery. A 45 minute charge provides about 70% charge for emergency power, and another 1 hour 15 minutes delivers 95% power. However, connect the QB-34, QB-37 or QT-47 for 2½ hours or longer whenever possible to bring your Quantum Batteries to 100% charge level. This assures maximum battery power and extends your cells' lifetime. However, it is not recommended to charge for more than two days at a time.