Charging Odyssey batteries is not as relaxed as many users believe. Charging should be limited to a voltage range of 14.2 to 15V per battery (trickle charge 13.8V). A 6A automatic charger is strongly recommended for the PC680. If you use a manual or larger automatic charger, a 10A charger should charge a flat PC680 in about 2 hours, a 20A charger 1.5 hours. I have been advised that charging above 6A reduces the life expectancy of a PC680 but not by how much! Chargers with less than 1.5A may not be able to charge a deeply discharged battery.