The 5 amp 12 volt Battery Tender charger is a fully automatic High Frequency switch mode charger.
This charger has a 4 stage charging cycle (Qualification, bulk, absorption and float).
When the recharge is complete the charger will float the battery for an extended period of time at full state of charge. This is specifically designed for AGM batteries but will easily recharge all lead acid batteries. Form the small Powersports batteries up to and including large deep cycle batteries for virtually any lead acid battery.
It is completely safe and includes a 72 hour timer to prevent further damage to marginal batteries. It is a smart charger that you just put on and leave on until you are ready to use the vehicle.