1989 Johnson Evinrude "CE" 9.9 thru 30 Service Manual, P/N 507754, Page 281Get this manual
3Capacity Test Satisfactory capacity tests can be made only when the battery electrolyte equals or exceeds 1.225 specific gravity at 80 (27 C) [IJ 4
Terminal Voltage Test
Use extreme caution during any load testingImproper procedures could overheat battery and cause electrolyte gassingThis might create 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 seconds If 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 testing Follow equipment manufacturer's instructions regarding test period and meter readings cEngine Load for Resistance Disconnect charge coil connectors between armature plate and power packConnect voltmeter across the batteryCrank engine for 15 secondsIf voltage is .6 volts or higher at the end of 15 seconds, the battery has good output capacity