1998 Johnson Evinrude "EC" Accessories Service Manual, P/N 520213, 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 "mari ne" Ventedrefillable or maintenance-free thru V4Rated 360 CCA (465 MCA) with 90 minutes reserve or 50 amp-hr
150175, 200225, vaRated 500 CCA (620 MCA) with 90 minutes reserve or 60 amp-hr 150175 FFr Rated 675 CCA (845 MCA) Group 29, or 107 amp-hrUse 750 CCA (940 MCA) battery when operating in temperatures below 32 (00 C)Deep-cycle batteries are suitable IF they meet or exceed the minimum CCA requirementsInstalling and Connecting Batteries and Cables Install each battery where it is protected from the elements and held in place during boating operation, yet accessihle for maintenance and periodic checking Tighten the hold-down or strap evenly and securely, but not to the extent that it distorts or damages the case If you use battery box, it must be vented and the lid installed so the connectors are insulated