Mercury Mariner Service Manual 6, 8, 9.9 210CC Sailpower, Page 22Get this manual
Specific gravity of electrolyte varies not only with percentage of acid in liquid but also with temperatureAs temperature increaseselectrolyte expands, so that specific gravity is reducedAs temperature drops, electrolyte contracts, so that specific gravity increasesUnless these variations in specific gravity are taken into account, specific gravity obtained by hydrometer may not give true indication of concentration of acid in electrolyteA fully charged battery will have specific gravity reading of approximately 1.270 at an electrolyte temperature of BO (27 C) If electrolyte temperature is above or below BO F, additions or subtractions must be made in order to obtain hydrometer reading corrected to BO standardFor every 10 (3.3 C) above BO F, add specific gravity points (.004) to hydrometer reading Example: hydrometer reading of 1.260 at 110 (43 C) would be 1.272 corrected to BO F, indicating fully charged batteryForevery 10 below BO F, subtract4 points (.004) from the readingExample: hydrometer reading of 1.272 at (-1BO C) would be 1.240 corrected to BO F, indicating partially charged battery Charging Discharged Battery