1995 Johnson/Evinrude Outboards 25, 35 3-Cylinder Service Manual, Page 224Get this manual
3Capacity Test Satisfactory capacity tests can be made only when the battery electrolyte equals or exceeds 1.225 specific gravity at 800 (2r C) m 4Terminal Voltage Test
extreme caution during any load testingImproper procedures could overheat battery and cause electrolyte gassingThis might cause an explosive atmosphereaVariable Load High Rate Discharge Tester (Recommended) Connect tester to battery terminal postsDischarge at rate of three times battery ampere hour rating for 15 secondsIf the voltage is 9.6 volts or higher at the end of 15 seconds, the battery has good output capacitybFixed Resistance Tester This equipment has built-in load for high-rate discharge testingFollow equipment manufacturer's instructions regarding test period and meter readingscEngine Load for Resistance Twist and remove the spark plug leadsConnect voltmeter across the batteryCrank engine for 15 secondsIf voltage is 9.6 volts or higher at the end of 15 seconds, the battery has good output capacityBattery 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 "Iight load test If batteries are to be fully charged by means of quick charger, the charge rate must be "tapered" (reduced to safe limit) when the electrolyte temperature reaches 1250 (52 C), or when gassing becomes excessiveFailure to do so may harm the battery&