The condition of liquid electrolyte solution is determined by measuring SPECIFIC GRAVITY with
a HYDROMETER. The specific gravity reading on the scale of a hydrometer indicates the
weight of the chemical content of electrolyte solutions.
When the specific gravity reading on a hydrometer scale indicates that the weight of the
chemical content of the electrolyte is below a given standard, the cell or battery must be
recharged or else have the correct chemical added to adjust the specific gravity.
Figure 1-8. Hydrometer.
The INTERNAL CONDITION of battery cells is determined by performing the high-rate
discharge test. This test will indicate the terminal voltage of a cell when an external load is
placed on it.