This 12-volt battery tender constantly monitors the battery without the possible damaging effect of trickle charges (boiling dry or over-charging). Initial charge brings the battery to full charge at approximately 14.2 volts, after which the charger converts to a float charger, monitoring at approximately 13.6 volts. Although there is a constant charge being applied to the battery, there is little or no current (approx. 10 milliamp). One snap cord included.