1990 Johnson Evinrude "ES" 9.9 thru 30 Service Manual, P/N 507871, Page 279Get this manual
3 Capacity Test Satisfactory capacity tests can be made only when the battery electrolyte equals or exceeds 1.225 specific gravity at 80 (27 C)4Terminal Voltage Test
Use extreme caution during any load testing Improper procedures could overheat battery and cause electrolyte gassingThis might create an explosive atmosphere aVariable 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 readings Engine Load for Resistance Disconnect charge coil connectors between armature plate and power packConnect voltmeter across the batteryCrank engine for 15 seconds If voltage is 9.6 volts or higher at the end of 15 seconds, the battery has good output capacityU