1997 Johnson Evinrude "EU" 90 thru 115 90 CV Service Manual, P/N 507267, Page 245Get this manual
Cranking Discharge Method 1Check battery voltage If voltage is greater than 12.5 volts, go to Step If voltage is less than 12.5 volts, go to Step 32Separate the ignition charge coil connector(s)Crank engine in short bursts until battery voltage is less than 12.5 voltsCheck battery voltage with key in the OFF position
INote Disconnect engine battery cables before proceeding with
this check3Connect 0-40 amp ammeter in series between the rectifier regulator red lead and the battery side of the starter solenoid4Reconnect the engine's battery cablesReconnect the ignition charge coil connector(s)