I have been using a 12 volt motor cycle battery charger for a long time, it has a 1 amp and a 2 amp setting.

I watch the voltage with a digital voltmeter and take it off charge when it peeks out. That is to say when the voltage drops down about .3 volts from the highest reading , its fully charged. I get very long battery life doing this.

lower charge rates are easier on a battery , when over charged. But its still hard on them and takes away from the life of the battery.

Lead acid batteries should NOT be charged by a constant current charger as suggested by some. Instead they should be charged using a constant voltage source that is preferably current limited to reduce initial charging current. The voltage should be set to approx 2.30-2.35 V/cell and the initial current limit to somewhere between 10 to 30% of the stated capacity. For a 12V, 7Ah battery a voltage of 13.8-14.1V and a maximum initial current of 0.7 to 2.1 A. is about right. As the battery is charged the current will decrease automatically to approx. 3-4% of the rated capacity, i.e., 0.21-0.28A for a 7Ah battery. When this happens the battery can be considered fully charged.

Some automotive chargers like mine have a selection for charging Gell Cells