Sears 1.5 amp charger

[stinger222]

I've got one of those 1.5 amp trickle batt chargers from Sears. Does it hurt to leave it plugged in all the time when the boat is sitting at in the slip? Will it overcharge the battery, or will it just maintain the charge. I'm not sure if this one shuts off when it reaches a full charge, but someone told me it doesn't matter because its only throwing 1.5 amps in there and its not hurting the battery.