1990 Johnson Evinrude 120 thru 140, 185 thru 225, 300 HP, P/N 507875, Page 312Get this manual
Battery Specifications
INote' All batteries should be of heavy duty, marine constructionV4
Maintenance-free (sealed type) batteries can be used with Loop "V" models
For best performance, OMC recommends 12-volt battery with minimum rating of 360 amps cold cranking at (-18 C) and 115 minutes reserve capacity rating at 80 (27" C)V6,V8 For best performance, OMC recommends 12-volt battery with minimum rating of 500 amps cold cranking at (-18 C) and 99 minutes reserve capacity at 80 (27" C)Battery Devices Battery IsolatorsIf you are rigging Loop "V" model where the engine's charging system will support two or more batteries, you should only use one of the following battery isolator devices: One engine to two batteriesModel 2420 One engine to three batteriesModel 2424 Two engines tc? three batteriesModel 2423 The above battery isolators are manufactured by Guest Products Battery "On-Off" SwitchesIf you are using battery master "On-Off" switch in the engine's 12 volt electrical system, be sure that the switch is equipped with "makebefore-break" circuit to protect the engine's battery charging systemAvoid switching while the engine is running and never turn the switch "off" unless engine is stoppedBattery Testing