1968 Evinrude Starflite 100 HP outboards Service Manual, Page 81Get this manual
iceIf none of the cells come up to 1.95 volts after the first boost charge, the battery should be given second boostBatteries which do not come up after second boost charge should be replacedBATTERY CHARGING Boost charge 12-volt batteries at 50 amperes for 20 minutes (1000 ampere minutes)If the charger will not give this rate, charge for an equal number of ampere minutes at best rate availableDO NOT boost battery more than this amount for the "light load test"If batteries are to be fully charged by means of a
Correct battery polarity is extremely importantThe battery MUST be connected so its negative post (-) is connected to groundIf the positive post is connected to ground, the pulse pack and voltage suppressor will instantly be damaged, and the rectifier diodes may also be damaged