Charging a battery is best done by the slow charging method (often called trickle charging), with a low amperage charger. Quick charging a battery can actually "cook'' the battery, damaging the plates inside and decreasing the life of the battery drastically. Any charging should be done in a well ventilated area away from the possibility of sparks or flame. The cell caps (not found on maintenance-free batteries) should be unscrewed from their cells, but not removed.
If the battery must be quick-charged, check the cell voltages and the color of the electrolyte a few minutes after the charge is started. If cell voltages are not uniform or if the electrolyte is discolored with brown sediment, stop the quick charging in favor of a trickle charge. A common indicator of an overcharged battery is the frequent need to add water to the battery.
When it becomes necessary to replace the battery, be sure to select a new battery with a cold cranking power rating equal to or greater than the battery originally installed. Deterioration, embrittlement and just plain aging of the battery cables, starter motor and associated wires makes the battery's job all the more difficult in successive years. The slow increase in electrical resistance over time makes it prudent to install a new battery with a greater capacity than the old. Details on battery removal and installation are covered in Section 3.