With 4 Amps of power, it can quickly take batteries from dead to ready-to-start in under 2 hours. The Automatic voltage detection makes this charger incredibly easy to use, simply connect it to your battery and it automatically selects the correct charging voltage for your battery type. The voltage selection button allows you to manually set the voltage if you prefer. To charge 12 volt Lithium ion batteries, just press and hold the lithium ion button for 3 seconds, its that simple. The charger’s multi-stage charging feature automatically adjusts the current and voltage based on the charging needs of your battery and ensure optimal charging performance and battery health.