Go Power GPC-45-MAX 45 Amp 3-Stage Converter/Battery Charger, Compact Design, UL Listed, Includes 15-Amp Male Plug, RV & Marine Applications

The charger is built to charge flooded or wet cell batteries to 100 percent by using 4-stage charging. The first stage of charge is called "bulk charge", this is when the charger puts its full output into the batteries. The second stage is "absorption" where the charger holds the batteries at 14.4 Volts direct current and tapers off the amperage going into the battery. The third stage is called "float" when the charger drops the batteries to a lower voltage of 13.5 Volts direct current to avoid excessive gassing of the batteries, this is done so you do not need to constantly fill the distilled water on your battery/batteries. The fourth stage is called "equalize" and this is used when you have more than one battery. Anytime you have more than one battery in a system, the two batteries will end up at different levels of charge. Equalize will charge the batteries to a higher voltage then normal to ensure that both batteries stay at the same charge level. The "equalize" is done automatically by the charger when the battery bank requires it.