A trickle charger slowly charges a battery. Trickle chargers are designed to add power to a battery at the same rate the battery discharges itself over short time periods. In this way, the battery charge can be sustained indefinitely, which is ideal for batteries that may not be used frequently, such as marine batteries. However, even though it delivers an extremely slow charge, some trickle charger models can only be connected to a battery about once a month for approximately two days to prevent damage to the battery cells and possibly cause a boil-over of battery acid. Other trickle charger models, commonly referred to as floater chargers, can be connected to a battery indefinitely. Review the owner’s manual to determine which type of charger you have before leaving it connected to a battery for more than a couple of days.
Set the switch on the front of the trickle charger to the correct voltage for the battery. For automobile, truck and most marine batteries, the setting will be 12 volts.