What is a hydrometer and how do I read one?
A hydrometer is used to determine the state of charge of each cell of a battery. The hydrometer will determine the cells specific gravity of electrolyte (its weight compared to water). A hydrometer is a bulb or tear drop syringe which will extract electrolyte from the cell. A float in the hydrometer is calibrated to read in terms of specific gravity. A common range of specific gravity used in these floats is 1.160 to 1.325. A common specific gravity reading is 1.250 to 1.280 in most climates for a fully charged battery, with a reading of 1.210 to 1.230 in tropical climates. A tropical climate is considered one in which water never freezes. In extremely cold climates, most batteries use a stronger electrolyte solution. A specific gravity reading for this climate could be 1.290 to 1.330. A higher specific gravity reading can, in most cases, decrease the service life of the battery. Should a reading occur in which the float does not float, you can assume that the cell is bad or that the b
