1996 Johnson Evinrude "ED" Electric Outboards Service Manual, P/N 507119, Page 20Get this manual
2Hydrometer Test (non maintenance-free batteries) This test can only be performed when there is sufficient electrolyte above the battery plates to fill the hydrometerIf electrolyte is too low, add water until level is correct Do not take readings immediately after adding waterRecharge battery to mix acid in water before testing3Voltage Test (maintenance-free batteries) Use voltmeter or "percent of charge" meter to determine condition and state of chargeRefer to your battery literature for the full charge voltage of your battery INote Disconnect battery cables from battery before connecting
battery charger clamps
View the hydrometer with your eye on the same level as the liquid surfaceThe float of the hydrometer must float freely and not stick to the sidesMake correction for the battery temperature
Specific gravity will vary points (0.004) with every 10 (6 C) temperature changeFor each 10 (6 C) below 80 (2r C)' subtract points from hydrometer readingFor each 10 (6 C) above 80 (27 C), add points to hydrometer reading After correcting to 80 (2r C)' interpret readings as follows: All cell readings the same at 1.250-1.260 specific gravity indicates battery is good and fully charged All cell readings uniform and below 1.225 specific gravity, recharge fully and retest Variation of more than 30 points (0.030) specific gravity between any two cells indicates battery condition is questionableRecharge and retestReplace battery if variation remains after recharging