1995 Johnson/Evinrude Outboards 9.9, 15 four-stroke Service Manual, Page 180Get this manual
Battery Cable Extensions The following are MINIMUM specifications for stranded copper cable without splicesCable measurements given are from the motor to the batteryThe maximum length is 20 feet, regardless of cable diameterINotel These specifications do not apply to aluminum battery cablesOMC does not recommend the use of aluminum battery cablesMinimum Recommended Gauge Total Extended Length10 ft(0,3m) 10 gao 1115 ft(3,44,6 m) gao 1620 ft(4,96,1 m) gao
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 (50 amp-hrs
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