1997 Johnson Evinrude "EU" Accessories Service Manual, P/N 507270, Page 58Get this manual
Battery Recommendations Electric Outboards All electric outboards should use one or two marine deep-cycle batteries with rating of at least 80 amp-hrGasoline Outboards
For each motor, provide one battery that is: 12-volt, heavy-duty, designated "marine" Ventedrefillable or maintenance-free thru V4Rated 360 CCA (465 MCA) with 90 minutes reserve or 50 amp-hr V6, V8Rated 500 CCA (620 MCA) with 90 minutes reserve or 60 amp-hr
Deep-cycle batteries are suitable IF they meet or exceed the minimum CCA requirementsInstalling 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