Battery Charging

Use a charger, with an end voltage of 16 V, equipped with a voltmeter that is accurate to within 1 percent.

The ambient temperature should be 15-38°C (60-100°F). A battery that is extremely cold will not accept immeasurable current for several hours after starting the charger.
^ The charging area should be well ventilated.
^ Do not charge the battery when the built in hydrometer is clear or yellow (3). Replace the battery if there is a cranking problem.
^ Do not charge a battery that appears to be frozen.
^ Batteries showing a green dot in the hydrometer (1) do not need to be charged unless they have just been discharged (such as cranking the engine).