General Information

When you charge the battery, observe the following conditions:
^ Use a constant voltage power supply with an end charge voltage of 16.0 Volts-Direct Current (VDC) and equipped with a voltmeter that is accurate within 1 percent.
^ When charging more than one battery, connect the batteries in parallel with each other; positive to positive (+ to +) and negative to negative (- to -).
^ Ambient (surrounding) temperature should be 15-38°C (60-100°F). A battery that is extremely cold may not accept current for several hours after charging has begun.
^ Ventilate the charging area.
^ Do not charge the battery if the built-in hydrometer is clear or light yellow. Replace the battery if you discover this condition. Refer to Battery Hydrometer Displays Dark or Yellow Dot. Battery Hydrometer Displays Dark or Yellow Dot
^ Do not charge the battery if the electrolytes are frozen.
^ If the battery feels hotter than 52°C (125°F), or if violent gassing or spewing of electrolyte through the vent holes occurs, discontinue charging or reduce the charging rate.