1990 Johnson Evinrude "ES" 9.9 thru 30 Service Manual, P/N 507871, Page 277Get this manual
Battery Specifications All batteries should be of heavy duty, marine constructionThe battery must be vented, refillable typeA battery that is not fully charged or less than recommended capacity may not crank the engine fast enough to produce ignition component output9 .9 thru 30 For best performance, we recommend 12-volt battery with minimum rating of 350 amps cold cranking at (-18 C) and 100 minutes reserve capacity at 80F (2rC)Battery Testing Battery electrolyte is an acidic solution and should be handfed with careIf electrolyte contacts any part of the body, immediately flush the exposed area with liberal of water and seek medical aid as soon as possible