Battery Detection The charger will automatically select the correct charging voltage based on the battery voltage type. The 6V or 12V symbol will light up on the LCD display depending on the battery type that is connected to the charger. Battery Bar Indicator The LCD display shows the battery state of charge by the percentage on the battery bar. The battery bar will flash as the battery is being charged. The battery bar will increase as the battery state of charge increases and will keep constant at 100% when it is fully charged.