1998 Johnson Evinrude "EC" 40 thru 55 2-Cylinder Service Manual, P/N 520206, Page 265Get this manual
Battery Specifications
For each motor provide one battery that is: 12-volt, heavy-duty, designated "marine" Ventedrefillable or maintenance-free Rated 360 CCA (465 MCA) with 90 minutes reserve or 50 amp-hr
Deep-cycle batteries are suitable IF they meet or exceed the minimum CCA requirements
Installing and Connecting Batteries and Cables Place the battery so it is easily accessible for frequent checking and recharging and in hold-down systemInstall positive cable to positive post and negative cable to negative post
rn When connectingoverthe battery, begin by placing largeto surface starwasher the threaded battery post, then stack
cables from accessories, then cables from the motorFinish the connection with hex nut, tightened firmly with wrench